Electric start for suitcase inverter generator by using its alternator as a BLDC motor?

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 I'm posting here in the hope that I can get some guidance on how to add  
an electric start feature to a cheap inverter generator cursed by the  
traditional recoil pull starter (the Devil's invention, imho). Apologies  
beforehand for what is a rather long initial post but I thought it best  
to appraise you of my thoughts and what I know of the problems involved  
in my proposed electronic add-on starter solution.

 Not too long after purchasing a Parkside PGI 1200 B2 inverter genset  
from Lidl (UK) for the miserly sum of 99 quid about two months ago (third  
time lucky[1]), I was wishing for an electric start feature to relegate  
its accursed recoil starter to that of 'emergency only' status.

 Now an obvious way to 'electric start' such ICE powered kit cursed by  
the infamous 'recoil starter', is to use a cordless electric drill with a  
socket wrench on a longish extension mounted in the chuck to crank the  
engine into life via the retaining bolt head on the exposed end of the  
engine shaft. In the case of that PGI 1200 B2, this isn't an option since  
the inverter module blocks such access.

 Having already viewed the innards of this model of suitcase generator, I  
knew that buying an add-on electric starter motor option was, well, not  
an option. I did briefly entertain the notion of a Heath Robinson  
electric drive attachment to the starting rope handle or even something  
that would turn it into a less obnoxious 'kick start' mechanism before it  
occurred to me that the damn thing was already possessed of the necessary  
starter motor essentials - it just lacked the required BLDC motor drive  
module circuitry was all.

 What had inspired me were several youtube videos I'd come across several  
months earlier, demonstrating the use of car and truck alternators as BLDC  
motors using R/C brushless ESC modules (a radio controlled (BLDC motor)  
Electronic Speed Controller). In particular, this video at:-

where a purpose made electric scooter BLDC module had been used rather  
than a cheaper R/C brushless ESC .

 In this case he'd used a 1500W rated module. I'm obviously not going to  
want to push more than double the alternator's 5 or 6 amps maximum rating  
through its windings so I reckon something like a 40 dollar  
SPD-3648350BLDC module would more than suffice with its 18A maximum  
current limiting feature. However, if I'm going to use such low voltage  
modules, I'll obviously have to add a high voltage isolating relay  
(probably a solid state one for speed and reliability) to protect it  
against the 350/400 voltage once the engine has fired up.

 It turns out that I'm not the first to ponder the possibility of  
doubling up the utility of the three phase multi-pole PM 170/340v  
alternator that's used to supply the inverter module with the required  
175 to 200/350 to 400vdc (120v 60Hz/240v 50Hz gensets), by adding a  
suitable BLDC motor drive module along with a 12v battery and a converter  
to produce the required 48 vdc to crank the engine at 400 to 500 rpm  
(just 10 to 12 percent of its normal running speed, circa 3900 to 4600  
rpm). A google search took me to the "allaboutcircuits" forum where a  
member had posed the exact same question way back in February 2011



 He had pretty much the right idea although his thoughts about using a  
170v converter to power a modified R/C brushless ESC and a cranking speed  
of only 100rpm were rather at odds with each other (never mind that such  
controllers typically max out at 6 cell's worth of LiPo battery pack  
voltage (22.2 to 25.2 volts) and 100rpm would most likely be far too slow  
to generate sufficient voltage to initialise the inverter and ignition  
module(s). Unfortunately, he didn't receive any helpful replies.

 In the case of the 120v 60Hz inverter gensets, a repurposed cheap  
commodity R/C brushless ESC probably would suffice - sadly for me, not so  
in the case of the 230/240v 50Hz inverter gensets. :-(

 I figured that a minimum cranking speed of 400rpm would be needed[2],  
necessitating at least ten percent of the 350 to 400 peak voltage  
generated at 4000 rpm to power the BLDC motor module which equates to a  
40 to 50 volt requirement for a cranking speed of 4 to 5 hundred rpm.

 I might be able to get away with half that voltage (and cranking speed)  
if I can use the starter battery to power the ignition module.  
Unfortunately, I don't have a workshop manual with schematic diagram(s)  
for my specific generator to check out the viability of such a  

 Considering just how old that forum posting is (over 7 years old!), I'm  
surprised at the absence of such an electric starting option in the  
inverter modules used in current designs of commodity inverter suitcase  
generators available today. After all, the extra components could quite  
easily be integrated into the inverter module since they're essentially  
just an extra bit of Silicon 'real estate'.

 Anyhow, those are my thoughts on the modern day version of the Dynastart
(tm) system as used with a small two cylinder four stroke marine gasoline  
engine (auxiliary propulsion and battery charging in a 30 foot sailing  
sloop) where a specially designed dynamo was also used to provide  
starting torque via a pair of V belts wrapped around a 50cm or so  
diameter engine flywheel grooved to accept said drive belts.

 My main problem is more to do with sourcing suitable hardware as well as  
trying not to re-invent the wheel if I can avoid it. For all I know,  
purpose made for inverter generator 'electric starter kits' may already  
be available (it is 2018 after all!).


[1] The 1st one ran just long enough to prove it was immune from the  
dreaded capacitive loading induced overvolting effect that ordinary  
petrol (gasoline) generators are afflicted with (the real reason why  
they're unsuited as backup power for UPS protected computer kit), before  
it dislodged the alternator connection to the inverter module and kicked  
out with an overload signal.

 The 2nd unit failed to start until I disconnected the low oil level  
sensor wire. The engine vibrations unstuck the jammed oil level sensor  
float but since I'd initially assumed it was a low oil *pressure* switch,  
I was reluctant to keep hold of it so it too went back to Lidl for a  

 By the time I'd discovered the true nature of these show stopping faults  
(and the ease by which they could be fixed), the original store had run  
out of stock. However, to my surprise, another local Lidl store turned  
out to still have three left so I bought two to reduce the risk of them  
being out of stock should my next one also need to be swapped out. Both  
proved to work ok so I chose what I thought was the better example and  
returned the 'spare' for a refund.

 The problem with these Parkside inverter generators was less to do with  
Parkside's quality control and more to do with Lidl's oddball stock  
control whereby unsold stock *has* to make way for "The Next Week's  
Offers" since the shop floor is also the store's only warehousing space,  
resulting in these generators accumulating hundreds, if not thousands, of  
road miles over the UK's motorway network, being shunted from store to  
store or main depot. It's no wonder that oil sensor floats get jammed or  
connectors dislodged (BTW, both trivial to fix issues once you're aware  
of them).

 As inverter generators go, they seem nothing short of perfection  
compared to other commodity inverter gensets in this market segment. It's  
true they're not as quiet as the Honda inverter generators but, until  
very recently, Honda were in a class of their own in this regard.

[2] This was after guestimating the power strokes per second rate I could  
achieve with the recoil starter (ignition off whilst re-priming the fuel  
line and float chamber) from which I could calculate a cranking rpm  
figure. It sounded about 5 such cycles per second, making it 10 revs per  
second or 600rpm.

 My gut feeling is that 4 to 5 hundred rpm should suffice. However, I  
could well be over-estimating the cranking speed requirement so it might  
pay me to simply buy (or better yet, borrow) a cheapish 6 cell rated R/C  
brushless ESC module to do some initial tests with a pair of 12v SLAs,  
with the spark plug removed and then fitted but ignition disabled before  
worrying about protecting the module from the 350/400 volts when the  
engine fires up. There's little point in worrying about adding a  
disconnect relay if this 'Proof of concept' testing fails to deliver any  
encouragement to proceed further.

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 01:20:32 GMT, Johnny B Good

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Electric drill starter.  Lots of YouTube videos showing various ways
to do it:


The basic trick is to use some kind of directional clutch so that when
the generator starts, it doesn't spin the drill out of your hands.  If
the generator already has a good clutch on the recoil starter, then
you don't need to add one.  However, if you're going to spin the drive
shaft directly, you'll need one.  Or, you could just use a socket
drive, butcher the shroud, and take your chances as in this video:

These are all the same but from multiple vendors:

Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?

Here's the product page for Jumpstart by Troy-Bilt:
and eBay:

Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On 11/07/2018 11:05 AM, Jeff Liebermann wrote:
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Umm, didnt the OP mention the access to the crankshaft was blocked ?

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 13:18:24 +0800, Rheilly Phoull wrote:

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 I did indeed! I guess that's one good reason not to try and explain  
*everything* in one huge post (all too easy for such detail to get lost  
in the 'noise'). :-(

 I did check out the links on the off chance there were some that did  
*not* involve access to the nut on the end of the crankshaft. Believe me,  
if I'd had access to the crankshaft end, I'd have gone for that option in  
a heartbeat. I'm all for a pragmatic solution, talking of which, I'm  
considering the use of a cheap(ish) R/C brushless ESC module (6 cell LiPo  
version) with a couple of 12v SLAs just to test the viability of the  
whole "Turn the alternator into a starter motor" concept.

 Despite my misgivings about the limited cranking speed (200 rpm or so in  
this case), it might still prove sufficient - I've had the damn thing  
'kick back' when I've hit the compression point too soon to have built up  
enough speed due to not feeling my way just past compression (ignition  
off) to give myself a run up via the subsequent exhaust/induction/
compression strokes.

 As I've said before, it's all too easy to over-think the problem and end  
up over-engineering a solution. The need to save a 24v rated ESC module  
from getting fried by the resulting 350 to 400 volts when the engine  
fires up shouts "Over-engineered!" loudly enough as things stand already.

 My gut feeling is that the alternator can provide enough starting torque  
when run off a suitable BLDC motor controller module but I do wonder  
whether, in over 7 years, it's already been considered (after all, it  
*does* seem to be such a "No-Brainer" electric starting option) and  
discounted for the lack of the necessary 'grunt'.

 TBH, if you're going to give this option *any* thought at all, you'd  
consider using the microprocessor controller in the BLDC motor drive  
module to do something a little more sophisticated than merely emulate a  
dumb electric starter motor designed to brute force its way past the  
compression point.

 The key obstacle here is the torque required to overcome compression  
without any run up to recruit the flywheel inertia. I'm pretty sure  
there'll be more than ample cranking torque once the initial resistance  
to compression has been overcome and the engine starts turning.

 A blindingly obvious way to overcome this problem is to have the BLDC  
module crank the engine backwards until it hits and detects the  
compression loading before reversing the direction using the compression  
to bounce the shaft into rotating in the right direction with a whole 630  
degrees or so's worth of 'run up' to build up the necessary speed to  
carry through the next compression stroke without risk of 'kick back'.  
It's not as if the BLDC modules are lacking the 'Smarts' required to run  
such an algorithm - "Work smarter, not harder!" would the obvious  
solution in this case. :-)

 Assuming such an electric start system using the inverter genset's own  
built in three phase PM alternator for the 'grunt work' is viable (and I  
rather think it is), then there would seem to be a small window of  
opportunity for a cheeky startup to go into mass production of add-on  
electric start modules for the many thousands of commodity priced pull  
start inverter gensets already sold.

 I say "small window of opportunity" since such extra circuitry can so  
readily be incorporated into the inverter modules (where it's best  
implemented in the first place) of later production inverter gensets once  
the manufacturers realise they've 'missed a trick' by allowing a cheeky  
upstart company the opportunity to take advantage of their oversight.

 The manufacturers can charge a premium for the luxury electric start  
'feature' at little more than the cost of a lightweight 6 cell Li-ion  
battery pack and a few extra inches of wiring and an ignition/starter  
keyswitch. They can still charge a premium for generators that are merely  
"Electric start capable", requiring a battery and ignition switch upgrade  
kit bought from the manufacturer who will make a nice profit at the  
expense of any such cheeky upstart company.

 It's not as if any of this tech is costly to produce, so where the hell  
are all the "Inverter genset electric start upgrade packs"? :-)

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 13:18:24 +0800, Rheilly Phoull

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Probably, but I missed it in the flurry of words.  I couldn't find a
decent photo of the insides of the Parkside PGI 1200 B2 inverter
generator and therefore could not determine what might be blocking

Looking again, I find:

The operator was able to start it in one easy pull.  However, this
appears to be a different version of the generator, where the pull
starter is on a plastic panel that presumably could be removed.  That
would have been too easy.  Here's the manual for the INVERTER
The OP states that he has a B2, not A1 model.  Oh well.

This is the B2 model with the recoil starter between the engine and
the front panel:

Starting at 13:40, getting the B2 going took 13 pulls.  Yep, doesn't
start very easily.  Removing the recoil starter assembly and drilling
an access hole in the front panel might aesthetically disgusting, but
would do the job.  So much for new and improved.

The B2 manual is at:
Since the manual does not show an exploded view, I can't tell if
drilling a hole might work or if some kind of pancake form factor
motor might fit.

My next step would be to tear off the various plastic panels and let's
see what's inside.

Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 08:45:00 -0700, Jeff Liebermann wrote:

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 From new, pretty well all of these engine vacuum driven fuel pumped  
carburettors needed several pulls on the starter cord to finally prime  
the float bowl so, since this was effectively an unboxing video (but with  
very little actual unboxing shots), 13 pulls doesn't seem excessive in  
the circumstances.

 The priming procedure when the generator has been allowed to run the  
fuel line dry (float bowl and fuel pump and the line in between and the  
one to the fuel shut off valve) prior to being put into storage isn't  
quite so protracted (about five leisurely pulls with the ignition off to  
eliminate the recoil starter's nasty surprise of 'Kickback'). Thus  
primed, it usually starts on the next pull or two.

 I know some pull start inverter generators incorporate a 'Priming Bulb'  
to provide pulses of suck 'n' blow to operate the fuel pump independently  
of the engine but, like the piece of shit Workzone 1800/2000W inverter  
genset sold by Aldi a week ago that I sampled three of before concluding  
they were utter shite, this one isn't so blessed.

 A fuel priming lever would have removed a lot of the effort required to  
start it after its been retrieved from 'dry' storage. I could probably  
add a priming squeeze bulb without compromising the warranty but I'll  
wait and see how my electric starter project goes before I look to adding  
that enhancement (it won't matter so much with electric start but it's  
one hell of a bonus when your only option is that accursed recoil starter  

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 For that, you'll need to track down a workshop manual and they're rather  
thin on the ground for the cheaper commodity generators.
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 I'd already done that when I was delving into the 2nd unit which had  
suffered a stuck oil level float switch. The job would have been a lot  
easier if I hadn't been concerned about voiding the warranty by having to  
work around a bolt protected by a sticker obviously intended as an anti-
tamper label by bending the plastic side panel aside to gain minimal  
access to other fixing bolts and screws.

 The air intake vent at the front, opposite the rear end where the  
silencer and ventilation exhausts live, is straddled by the inverter  
module which blocks access to the recoil starter mechanism (the usual  
access to the flywheel retention bolt).

 I could probably replace the recoil starter mechanism with such a  
pancake motor, replete with a planetary reduction gearbox and free-wheel  
coupling, but I'd lose the emergency recoil starter option unless I can  
extend the case to refit it ahead of the pancake starter motor assembly.

 Considering what my options are with regard to relegating the pull cord  
to 'emergency use only', you can perhaps understand why I'm considering  
using the alternator as a BLDC starter motor.

 If it's at all viable, this completely eliminates any sort of  
complicated mechanical modification, reducing the job to a much easier to  
implement installation of a suitable BLDC motor drive module and a high  
voltage solid state isolation relay (unless I can get hold of a BLDC  
motor drive module designed to tolerate the expected 350 to 400v output  
when the BLDC motor starts operating as a high voltage alternator).

 Thinking about it, I don't really need turn on resistances as low as 7m?  
in a low voltage BLDC controller module since the alternator stator coil  
resistance is likely to be around an ohm per winding[1] so a higher motor  
voltage BLDC controller with turn on values measured in tens of m? rather  
than m? should nicely suffice in this case so I'm still floundering  
around looking for the best way to implement a practical and cost  
effective electric starter solution.

 If I can get enough cranking speed using just 24v, I can simply use a  
pair of 12v SLAs (or possibly a 6 cell Li-ion battery pack). If I need to  
use 40 to 50 volts, it would make more sense to stick with a 12v SLA and  
use a DC-DC boost converter module to generate the higher voltage. I'll  
probably need an 8A rated 48v converter module for this task (assuming a  
brute force approach to the task of overcoming compression resistance).

 In the meantime, I'll keep searching for suitable BLDC motor controllers  
and keep an eye on this thread for any further advice that might appear  
from those with more knowledge and experience in this field than my own.

[1] I haven't actually measured the stator windings resistance yet so  
this is just an educated guess. Furthermore for obvious reasons, the  
windings will most likely be connected in star (wye) rather than delta  
form with no access to the neutral point so regardless of the actual  
arrangement, I'll only be able to measure phase to phase anyway. However,  
that will at least inform me of the maximum possible stall current for  
any given BLDC motor controller supply voltage.

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 22:27:07 GMT, Johnny B Good

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Some motors have a primer bulb to manually pump gas into the carb.
Done correctly, I can start a small engine with one or two pulls of
the recoil starter.  Of the saws I own or have serviced, the worst is
my Stihl MS180 (upper right)
which takes exactly 6 pulls when cold starting.  However, once it runs
for a while, and the carb fills with gas, it will warm restart in one

I would consider 13 pulls to be rather excessive.

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Ok, that's normal.  Five pulls is about right.  I run my saws dry and
empty the tank in the fall, when I'm done using them (except for one
for emergencies where I put some Sta-Bil in the tank).  I haven't had
to disassemble, clean, or rebuild any carburetors for a long time.

Yes, kickback sucks.  It happens to me fairly often.  I pull on the
starter rope normally a few times.  Then, it acts like the starter
rope is stuck.  I pull on the rope, which lifts the saw in the air,
while simultaneously aims my face into the saw.  After a few close
calls, I'm VERY careful when starting a cold motor.

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Ummm... I take it that you don't like this inverter generator, and by
implication also don't like the primer bulb concept?  I don't want to
go into the pros and cons of primer bulbs.  Let's just say they're a
necessary evil without which you would be draining the tank and carb
after every use and possibly removing crud from the carb.

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I think a fuel shutoff petcock and carb drain would be more useful.
You would have the option of leaving gas in the tank as long as
necessary.  If it's been sitting for months, drain the carb, or flush
it with carb cleaner.  Most larger gas generators, motorcycles, and
paint sprayers have this feature.

You're not going to preserve the warranty after installing a starter
motor unless you're VERY careful.  Your decision.  Electric start or
warranty.  Pick one.

How many pulls does it take to cold start your generator?  If 13, then
maybe you have a point.  If 5, don't bother, and just get some more

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I think the term is "service manual".  I have one for almost
everything I own (usually in PDF format).  Unfortunately, many are in
foreign languages where Google Translate is nearly useless.  I
couldn't find a Parkside PGI 1200 B2 Service Manual.

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You should have taken photos.  These days, I don't work on anything
without taking photos of my work.  It's mostly to help remember how
things go together, but also to show others what is involved.

Use some solvent to loosen the glue on the label.  The solvent will
evaporate, but the glue will remain attached to the label.  When
you're ready to re-attach the label, a little more solvent will soften
the glue again.  This works on many labels, but not all of them.  Some
labels use ink that is soluble in chlorinated hydrocarbon solvents
resulting in a destroyed label.  On a plastic or painted case, your
choice of solvents may attack the plastic or paint.  Start at the low
end of the scale with 70% isopropyl alcohol and work your way up to
stronger (and more toxic) solvents.

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Ok.  Drilling a hole in the inverter module is not going to work.  

Can you remove the recoil starter, and attach a clutch and sprocket
gear to the drive shaft?  If so, you can attach a bicycle chain to the
sprocket gear and hang the starter motor out to the side.

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Since the recoil starter and electric starter want to both occupy the
same space, you'll have to decide which one you want.

(I'm out of time...)

Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 17:57:00 -0700, Jeff Liebermann wrote:

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 Just reviewing the thread and spotted a couple of points I should have  

distracted my attention. Sorry for that oversight and it's probably a bit  
late to address them now but I feel the need to do so anyway.
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 I think I tried a little too hard for 'conciseness' when I was comparing  
the shite workzone's lack of a priming bulb to the same lack in the  
Parkside unit and bemoaning this act of utter stupidity (no doubt the  
result of short sighted "Beancounteritis"(tm) at Parkside/Lidl HQ).

 Despite my remarks on the benefit of a fuel priming bulb, you seem to  
have the idea that I don't like the primer bulb concept when in fact I  
view it as a necessary *good* which would not only have reduced the  
effort of starting it from 'dry', but would also have tripled the service  
life of a recoil pull cord starter mechanism seemingly designed to fail  
long before the very first oil change service becomes due.

 If as a manufacturer, you must curse your ICE powered product with only  
a recoil starter option, then it behoves you to at the very least, spend  
an extra few pennies fitting the necessary mitigation device(s) to  
prevent its use becoming a danger to your customers' health and wellbeing.

 In the case of a generator, a fuel priming bulb is the absolute minimum  
you can provide, even better would be an auto-decompression release as  
well as the fuel priming bulb. I suppose in the case of a chainsaw, an  
auto decompression release mechanism would take priority over a priming  

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 That's why *all* ICE powered kit includes them as standard.  
Unfortunately, some genset manufacturers think they're doing their users  
a favour by the unforgivable sin of combing the fuel shut off lever with  
the engine kill switch.

 Workzone committed this very sin, compounded by saving a few cents on an  
eco-fast option switch, an especially egregious omission in view of the  
incredibly bad response it has to adjusting to just half of its rated  
load being switched on when it bogs down so severely, you're left  
wondering "How in Gawd's name did it not stall?"

 The Parkside genset is blessed with both a seperate engine kill switch  
*and* an eco-fast option switch, the value of which I never got the  
chance to appreciate until this Tuesday when I managed to stall it by  
switching on an 86% load before it had any chance to warm up.

 I restarted it easy enough and set it to fast idle before testing with  
my 900W toaster load to make sure it wasn't due to my having had the  
alternator disconnected to do some tests a little earlier. A few minutes  
later, I switched back to eco-idle mode and tried the 900W test again,  
proving it had returned to its impeccable response to sudden loadings  
where you can't detect any bogging down, just an immediate response to  
the throttle and stable power, so unlike that piece of shit Workzone  
sorry excuse for an inverter genset that I'd tried three examples of from  
Aldi a fortnight or so back.

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 I know all this, that's why I really appreciate the seperate from the  
fuel stopcock engine kill switch of the Parkside inverter genset, which  
allows me to run the carb float bowl and fuel line dry before I put it  
into extended storage.

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 I'm only connecting a plug-in 400vdc rated BLDC motor control module and  
a 48 or 60 volt DC-DC converter to run the alternator as a start motor.  
There'll be no gross mechanical modification involved whatsoever (I  
thought I'd made that totally clear in the first place).

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 The exercise I could do with but risking a premature failure of a cheap  
ropey pull start mechanism is something I'd prefer not to have to deal  
with, especially when I can convert to electric start without the use of  
excess baggage in the form of an add on starter motor whilst there's a  
perfectly capable BLDC brushless starter motor already fitted to the  
crankshaft in the guise of a 400vdc alternator come flywheel.

 A rather basic test recently with a 12v SLA to get some idea of the  
torque that can be generated by the alternator, suggests this pet project  
of mine is a lot more do-able than I'd hoped for. So much so that I think  
it's high time for me to track down a 400vdc 10A rated sensorless BLDC  
motor controller and a 5A 48v DC-DC converter to complete the project. :-)

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On 2018-07-11 15:27, Johnny B Good wrote:
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You don't need a fuel pump on a small generator, you need an external
fuel tank with some head.

Maybe if you bought some piece of cheap Chinese 2kVA shit on a
self-contained skid and threw it straight in your garage expecting to
plug it into an outlet when you need power later, it has a fuel tank
that's 2 inches above the carburator and you need to prime it.

Otherwise the float bowl ought to be full as soon as you turn the cutoff
valve on and it will start on the first pull.

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 18 Jul 2018 22:24:40 -0700, +++ATH0 wrote:

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 You do when you're making a compact suitcase inverter genset that you'd  
rather was no taller than it was long, if not for its aesthetics then at  
least in the interests of safety against it being accidentally knocked  
over onto its side.

 This design decision (not to go for that retro 80s look) often means the  
fuel tank can no longer be perched aloft of the engine's intake port just  
to create a gravity feed fuelling system. The one exception I'm aware of  
is Parkside's earlier PGI 1200 A1 with its classic pressed steel tank sat  
on top of a basic open frame fitted with cosmetic side panels.

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 The normal solution provided for gravity feed setups like you describe  
is the use of a carburettor float chamber that has a spring loaded  
priming button to let you flood the float bowl just prior to cranking it  
up. It's a neat and effective solution that also has the virtue of giving  
a positive indication that there is still fuel in the system and, more  
importantly, that it's reaching the carburettor float bowl.

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 Provided you allow a few second's wait for the float chamber to refill,  
that's generally true with most four stroke gensets, less so with two  
stroke units - they tend to play the startup game far less nicely.

 Anyway, all of the niceties of gravity feed fuel systems are rather  
beside the point in this thread. The inverter generator I'm trying to  
convert to electric start by adding a BLDC motor controller and starter  
battery to take advantage of the existing BLDC motor, currently passing  
itself off merely as a '400 volt three phase PM flywheel alternator'  
bolted onto the engine crankshaft, of necessity uses an engine vacuum  
driven fuel lift pump since the level of the fuel in the side panel tank  
is below the level required in the carburettor float bowl.

 I'm sure Parkside would have dearly loved to avoid the expense of an  
engine vacuum driven fuel lift pump, even as commoditised as such, made  
in their millions, components are cost wise - dirt cheap. The removal of  
the fuel tank from its 80s retro look location to a tank integrated into  
a side panel forced the use of just such a fuel lift pump. It's a  
solution but it does have its downside if the manufacturer short changes  
their customer out of some sort of fuel priming mechanism independently  
of having to hand crank the engine through half a dozen or more  

 It's just a shame that Parkside didn't in this case spring for the extra  
25 cents it would have added to the BOM costs to fit a priming button/
lever/squeeze bulb to manually operate said fuel lift pump to avoid  
tripling the wear and tear on an already "So cheap it'll fail before the  
first oil change" recoil rope starting mechanism.

 Never mind. It won't matter so much when I'll be able to start it using  
battery power to drive its already built in BLDC starter motor. :-)

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Thu, 19 Jul 2018 16:53:42 GMT, Johnny B Good

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I found a solution against cranking forever (on one of the Tooltech
small non inverter gen kits, see Yamaha ET650 / ET950).  
Drilled a 1.5mm hole in plastic panel cover directly in front of the
carb bell mouth, with a syringe I just squirt about 1.5 to 2 ml of gas
directly into the bell just before starting after a period uf unuse,
goes first pull every time doing this and saves arm and start mechanism!

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Fri, 20 Jul 2018 08:02:27 +0100, Charlie+ wrote:

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 Seems a neat enough solution, a minor bit of 'faff' prepping it up with  
a worthwhile payback in reduced wear and tear on both yourself and the  
pull cord starter. If it's a two stroke prime mover, that'll be an  
exceptionally effective trick, assuming it's not gravity fed with a float  
bowl priming button which would be the usual way to achieve the same  

 I couldn't find any detailed enough pictures of the ET650/950 gensets to  
clarify your description of the 'carb bell mouth' but I presume you  
drilled through the plastic ducting from the air filter box right where  
it goes over the carburettor's intake (the ducting on these gensets  
typically makes absolutely no concession to the concept of 'gas flowing'  
to maximise volumetric efficiency).

 As useful a trick as that is, as far as starting on the pull cord, I'm  
hoping to render such starting measures (squirting a dose of fuel down  
the carb's throat or, better yet, adding a priming bulb to the fuel  
pump's engine vacuum port) a very low priority feature by relegating the  
pull cord from 'only available starting option' to 'emergency backup  
only, very last resort starting option' by pressing the alternator into  
BLDC starter motor service.

 When I look at the design of these pull cord start inverter gensets, I  
see an electric motor/generator mounted on the crankshaft where the motor/
generator is only half used. As an engineer, only making use of half of a  
motor/generator's capabilities is, quite frankly, an engineering  
obscenity. If a circuit component can have more than just one function,  
it's the designer's duty to ensure that it gets used for more than just  
one function whenever possible, especially if it reduces the component  

 In this case, my correcting the original designer's oversight in letting  
the motor functionality of the motor/generator assembly go completely to  
waste is simply an exercise in good engineering practice to provide an  
electric start for no more than the cost of a cheap 4 or 7AH SLA battery  
and a sensorless BLDC motor controller module costing no more than 20 or  
30 dollars and weighing in at a couple of ounces (a few extra cents and  
milligrammes if properly integrated within the inverter/controller module  
in the first place).

 So far, Lasse Langwadt Christensen has been the only contributor who has  
actually addressed my query with regard to the problems of adding a BLDC  
motor controller into this rich mix of 400vdc alternator come circa 50vdc  
driven BLDC starter motor system I'm trying to retrofit to this  
surprisingly good quality pull cord start inverter genset.

 Quite frankly, considering all the seemingly high quality electronic  
expertise in this news group, I'm rather surprised at the dearth of  
advice in regard of the electronics aspect of my little project and the  
almost boundless advice (good though it is) in regard of solutions for  
improving the efficacy of the existing pull cord system of starting that  
I'm trying to relegate to "Last chance saloon, emergency only, when all  
else fails, starting option".

 Thanks to Lasse, I now know that I require a 400v 10A rated BLDC motor  
controller using 600v rated drive transistors to cope with the 400v  
generating output from the BLDC/Alternator once the engine fires up. This  
shifts the problem of mixing a circa 50v BLDC motor drive voltage supply  
with the resulting 400vdc back emf to the simple matter of using an 8A  
800v PIV anti-backfeed diode between the 50v supply and the generator  
output voltage.

 I don't need a sophisticated PWM drive, just a basic 'trapezoidal' six  
state switching 120 deg drive system (but one rated to cope with some 400  
volts or more of back emf). Since the three phase alternator may well be  
optimised to its use, after rectification, as a DC generator with minimal  
ripple voltage, it may well be better to use a simple trapezoidal current  
drive setup anyway. In any case, 'torque ripple' won't be an issue -  
indeed it may well prove an asset in this usage case.

 Since I'm not entirely sure of the BLDC motor drive's starting voltage  
requirement in this specific case (all I'm fairly certain of at this  
stage, is that 24v is unlikely to suffice), I'm planning on using a 12  
volt to 48 volt 7A rated DC-DC converter with galvanically isolated  
output so I can use the 12v battery to buck or boost the BLDC voltage  
between 36 and 60 volt to optimise starting performance for the minimum  
of stress on the starter battery.

 Now, all that remains of my project is the matter of sourcing the  
necessary components, sensorless BLDC and DC-DC converter modules (and an  
8A 800v rectifier diode). Any advice in regard of such modules and  
sources will be greatly appreciated thank you very much. If you have  
anything further to add, please, can it *not* be anything to do with pull  
cord starting techniques this time? :-)

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wednesday, 11 July 2018 02:20:36 UTC+1, Johnny B Good  wrote:
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You do realise that cheap gennies have very short operational lives, making
 extensive work on them pointless. If you want something worth tinkering wi
th get a Listeroid from some 3rd world country. Tinkering is not optional &
 they will run for a lifetime, day in day out, once fully built. Listeroids
 also use a fraction as much fuel as modern junkboxes.


Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 06:44:02 -0700, tabbypurr wrote:

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 Not quite as small a fraction as you might think. However, they can be  
run on duty free diesel for about half the cost of a petrol/gasoline  
generator. Indeed they're not fussy about what fuel oil you choose to run  
them on so you have a lot more fuelling options.

 Thank you for that sage advice. I do appreciate what you're saying but  
unfortunately, I'm not trying to live off grid and nor do I have the  
space to install such venerable machinery. On top of which, the standard  
generator heads typically fitted to these listeroids[1] no longer suit  
the needs of modern day lighting and computer loadings, particularly true  
in the case of my venerable Smartups2000 with its 9.4?F's worth of  
capacitive loading across its mains input which sends conventional single  
phase AVR controlled 230vac 50Hz alternators into a massive over-volting  
state as a result.

 Lagging current loadings are merely the usual low power factor issue  
without the overvolting effect on the standard AVR controlled single  
phase alternators used in conventional generators but the slightest sniff  
of excess leading current from just a single 3.3?F fluorescent lamp PFC  
capacitor across the output of a 2.8KVA generator was enough to send its  
nominal 230v north of the 275v mark. I'm sure you can appreciate the  
problem caused by the Smartups2000 with its 9.4?F's worth across that  
genset's output.

 There is a very good reason why I blew a whole 99quid on that Parkside  
PGI 1200 B2 inverter genset. Basically, it was because I knew the  
inverter type lacked this overvolting defect in the face of capacitive  
loads and so was the only viable backup option for my Smartups2000  
battery backed 'protected supply'. I could have spent over a thousand  
quid on SLAs to extend the autonomy of the UPS into the 8 to 12 hour  
region but even if they were never to be called upon to provide emergency  
backup power, I'd be lucky to see more than a decade's worth of service  
life from them before having to blow yet another grand's worth on a  
replacement battery pack.

 I don't expect to be running the generator for more than half a dozen  
hours a year (monthly half hour test runs being the most likely  
consumption of generator hours) but I like to be prepared against power  
outages to maintain all the lighting, the CH/DHW (pump, controller and  
zone valve), my IT kit (NAS box, desktop PC, a Gbit switch and a couple  
of routers) along with the 4K smart TV in the living room to allow the  
missus to watch her favourite soap operas without interruption.

 At just 1000W continuous (actually 980W) with a 1200W 30 seconds surge  
rating, it's a bit on the marginal side but surprisingly do-able  
(upgrading the lighting to LED was what proved to be the key to this  
unexpected result). I was tempted by Aldi's recent Workzone 1800/2000W  
inverter gensets (three times no less before I gave up the whole idea of  
a generator upgrade) but they proved to be quite frankly, pure  
unadulterated shite.

 Unless we're due another unusually mild winter, the risk of power  
outages due to the government's mishandling of the Nuclear power plant  
construction programme that is now woefully years behind schedule, looms  
ever larger so it seemed only timely to purchase a backup generator that  
was compatible with modern day lighting loads and computer kit.

 When Lidl put the latest B2 model on offer for just 99 quid two months  
ago, it was such a 'bargain of the decade' I just had to buy one, even  
though it was initially just to verify its compatibility with my  
Smartups2000. It was some 30 quid cheaper than the A1 version which I  
notice are still available in my local Lidl store (and rather  
surprisingly, still at their original elevated price of 129 quid).

 Needless to say, I wasn't in the least tempted. It wasn't just on  
account of their higher price but also because of their retro 80's 'Cheap  
two stroke petrol generator' looks complete with a gravity fed fuel  
system from the classic top mounted steel fuel tank.

 Don't be fooled by the side panels, they're just cosmetic coverings on  
an otherwise open frame chassis. It's true enough that the plastic  
carapace of the B2 model hardly improves its noise footprint over that of  
its predecessor but at least it has a slightly larger capacity tank and a  
more economic fuel consumption rating (0.68L/hour at 67% loading versus  
the 0.88L/hour of the A1 model, also at 67% load).

 TBH, those little PGI 1200 B2s are such a bargain at 99 quid that if  
they ever become available again at that price, I'd snap up another two  
just to keep one as a spare (never mind that if either or both prove to  
have their first overload thresholds set above the nominal 1000W limit  
rather than 2% below it as is the case with my current unit, I'll be  
swapping inverter modules to correct the shortfall (unlike most inverter  
modules, the one used here is completely devoid of trimpots), hopefully  
leaving me with a pair of gensets both set above the 1000W limit for  
their first stage overload state (where you have 30 seconds to remedy the  
overload before the inverter module shuts down). The 1200W surge rating  
is the upper limit which, if exceeded, will trigger an immediate shut  

 If only one or neither meets or exceeds the specified overload limit, it  
just means I'll have to carry on the exchange/refund dance until I either  
land up with two good units or else run out of exchange options.  
Hopefully, my current inverter genset is the exception rather than the  
rule over this business of being set 2% below rather than 2 to 5 percent  
above the specified limit.

 This time round, I'll know exactly how to deal with the two most common  
stock faults that arise from their being mishandled in transit, stuck oil  
level sensor floats and dislodged connectors in the wiring going to the  
inverter module - both show stoppers yet trivial to fix. :-)

[1] Obviously, a permanent magnet three phase alternator wired to a high  
voltage rectifier pack and geared to produce 420vdc on no load could be  
used to power an inverter module (in essence a bridged pair of class D  
amps driven from a 50Hz sinewave reference signal) to get round this  
voltage instability impediment as well as improve on the best efficiency  
of the standard single phase alternator typically used to directly  
generate the required 50Hz 240vac voltage supply.

 As long as the DC voltage feeding the inverter module doesn't dip below  
340v, it will be able to sustain the 240vac right up to its maximum rated  
current limit, assuming of course that this doesn't exceed the three  
phase PM alternator's maximum ratings.

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Thursday, 12 July 2018 04:43:31 UTC+1, Johnny B Good  wrote:
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marketing speak

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not hard to add an inductive load to protect against capacitive loads

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sounds more pointless than I expected
Gas lighting is cheap & reliable, far more of both than any genny.

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that's a hard way to do a simple task.


Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Wed, 11 Jul 2018 21:29:09 -0700, tabbypurr wrote:

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 Yeah, I used to think that too. :-(

 Believe me, that's exactly what I tried but it failed to remedy the  
problem. In retrospect, I'd have been better off fitting a 4.7?F PFC  
capacitor to the generator to force the rotor into saturation and use an  
auto-transformer to step the resulting 280vac back down to 240vac. Once  
afflicted by a modest capacitive loading, any additional capacitance  
would have had little if any further effect (other than for the issue of  
the extra leading current being drawn). However, I'd have been placing  
additional stress on the stator windings so probably not the best of  
pragmatic solutions.

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 You're entitled to your opinion but I think you've rather missed the  
point of the exercise.

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 Not in these modern times with cheap commodity priced 'electronic  
solutions'. :-)

 BTW, why are you subscribed to SED if you deem such a solution to be "a  
hard way to do a simple task."? That view would have been valid three  
decades back when such 'complex solutions' would have required a complex  
circuit board populated with hundreds of discrete components including a  
microprocessor with a few dozen series 74 TTL chips thrown in for good  

 Now that all of that required silicon wizardry (and more) can be  
packaged into a one square inch PCB weighing a mere 6.6g (30A cont 25.2v  
brushless ESC module designed to drive a quadcopter motor - product code:  
FPV 30A-6S) for less than 20 quid (<https://tinyurl.com/ya53tojp ), such  
a view seems somewhat antiquated today. Presumably (BICBW) you're  
subscribed here to get up to speed on modern electronic technologies and  

 The inverter modules are much bigger since they're dealing with power  
conversion from an unregulated 350vdc supply to a constant 50Hz 230vac at  
the kilowatt level where, even with a conversion efficiency of 97 to 98  
percent, you still have to deal with some 25 to 40 watts of dissipation  
whilst keeping device temperatures below the 398K mark in ambient  
temperature conditions up to 313K or higher.

 The modules, as a consequence of this requirement, are mostly heatsink,  
shaped to allow the whole attached PCB to be fully embedded into a tough  
epoxy potting compound to protect against the harsh environmental  
conditions imposed by a small ICE running in the exposed conditions of an  
exterior environment.

 Combining a mechanically simpler PM three phase alternator with a  
dedicated inverter module is both cheaper to manufacture and more  
efficient than the more traditional single phase 50Hz 230vac alternator  
which uses a voltage regulator system that draws power from its output to  
drive magnetisation current through the field winding via a set of slip  
rings and brushes. The energy loss in an inverter module is only a  
fraction of that consumed in the field winding of a conventional AVRd  
single phase 50Hz 230v alternator of equivalent power output.

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Thursday, 12 July 2018 19:43:48 UTC+1, Johnny B Good  wrote:
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it's meaningless. And if you were to ascribe it a meaning, still valueless.
 Classic marketing talk.

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Not enough inductive current I presume.

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I have if there is one.

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with respect there are easier ways. I'm sorry if pointing that out upset yo


Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Thu, 12 Jul 2018 17:43:20 -0700, tabbypurr wrote:

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 That still doesn't really make a lot of sense. I looked at the fuel  
consumption graph for bio-diesel and for the 1KW point on the graph it  
equated to 0.64 litres per hour which is only slightly less than the 0.68  
litre per hour figure for the 670W output level of the PGI 1200 B2. To be  
fair, that's an apples and oranges comparison but I don't have a graph  
for the Parkside units.

 Alternatively, at the 700W level, the Listeroid graph shows a 0.15 US  
gal per hour rate which equates to 0.57 litre per hour despite the  
reduced efficiency of the consumption per KWH figure which flattens out  
in the range 1250 to 2500 watts at a per KWH peak of 0.5 litre per KWH of  
energy generated. When you look at the 500W figure that per KWH  
consumption hits the 0.98 litre mark which is likely much higher than the  
Parkside's consumption rate at this production level (500W load).

 If the generator spends most of its run time operating at the 300W  
level, the litre per KWH rate gets even worse leaving the Parkside the  
winner in this case but, of course, that neglects the much lower cost per  
litre of duty free diesel over that of petroleum (gasoline).

 Also, the Listeroid graph is handicapped by the use of a conventional  
single phase 230v alternator generator head and the extra losses of a  
drive belt totally absent in the case of the direct drive PM three phase  
alternator powered inverter suitcase generator.

 For anyone living off-grid, the choice of a large low revving diesel  
prime mover to drive a generator head (whether it's a conventional single  
phase 230v alternator or a geared up three phase PM alternator with  
inverter module), is a no-brainer one. However, for someone looking for  
an emergency backup generator to mitigate winter outages or looking for a  
more luxurious wilderness trekking experience, the lightweight suitcase  
inverter genset becomes the no-brainer option (that 1KW Parkside unit  
only weighs in at a mere 13Kg!).

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 Judging by the effect it had on my first Parkside genset, I'd say it had  
provided ample inductive current. I'd forgotten that I still had it in  
circuit when I hooked up the first generator to the cable leading into  
the basement to my Smartups2000 (not yet plugged into the business end of  
that cable), so was surprised when the generator started labouring when I  
plugged it in.

 The extra vibration must have been the final straw on the already  
loosened connector because after correcting my mistake by removing the no  
longer required inductor, I only got about 30 seconds run time before the  
generator stopped with an overload signal as a consequence of one of the  
phases disconnecting. Luckily, this had been just long enough to verify  
that I no longer had a capacitive over-volting issue with the Smartups2000  
so was happy to seek a replacement rather than a refund from Lidl.

 It was just unfortunate that this 2nd one wouldn't start because of a  
stuck oil level sensor float until I disconnected a suspiciously loose  
single wire connector which proved to be said engine sensor terminal  
connection which, like the oil pressure warning switch used in automotive  
engines which signal the lack of pressure by completing the connection to  
engine chassis earth to light up a warning light on the dash - in this  
case disable the ignition to prevent the engine destroying itself for a  
lack of oil rather for a lack of oil pressure.

 Unfortunately at that time, I hadn't come across the comments which had  
mentioned that it was a float level sensor that could end up jammed by  
transit handling abuse rather than, as I'd initially presumed, a pressure  
sensing switch which, despite the engine vibrations unjamming the float,  
left me a little uneasy about the possibility of an intermittent fault in  
an oil pressure sensing switch.

 If I'd been aware of the true nature of this low oil sensor, I wouldn't  
have felt the need (out of the principle that "discretion is the best  
part of valour") to return it to Lidl for yet another replacement it  
turned out they didn't have which left me without a generator until I  
discovered another cache of three a week later in another local Lidl that  
I'd wrongly assumed wouldn't have been chosen to stock this "bargain of  
the decade".

 Remembering my several trips back and forth with the first two, I bought  
two with the intention of returning the surplus unit for a refund once  
I'd decided which of the two was going to be 'surplus to requirements'  
after checking for the stock faults I had now become aware of by this  

 If both had proved defective, I could have returned both in one trip  
rather than two seperate trips. As it happened both checked out ok  
leaving me to select which to keep hold of on the basis of minor niggles.  
Unfortunately, it never occurred to me to verify the claimed overload  
wattage calibration setting so I landed up with the one that signalled  
this state at the 980W mark rather than the expected 1030 to 1050 watt  

 I suppose it's just possible that the other could have been set exactly  
the same, possibly all of them, in which case I'd be left to consider a  
calibration error on my test equipment being on the wrong side of the  
+/-3% accuracy tolerance range (both my analogue and two digital  
wattmeters being within 1% of each others' readings in the 1 to 1000W  
range makes this unlikely though not impossible).

 If Lidl ever put these B2 models back on offer at the same 99 quid  
price, I'll be snapping a couple of them up for testing. At that price,  
it's well worth holding a spare in reserve anyway.

 Normally, with such miscalibration issues as this, I'd be adjusting the  
relevant trimmer. Unfortunately, the inverter module used is completely  
devoid of any such trimmers - presumably they're preset in the factory  
(possibly via a JTAG connector - there are a couple of unused header  
blocks that could be candidates for this function).

 If I ever track down the relevant JTAG programming instructions, I'll  
trouble myself to bodge up a connector and configure an interface for the  
PC or laptop, otherwise my best bet is to acquire more examples and  
select the best (inverter module).

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 Not annoyed, irritated? yes! but annoyed? no.

Ok, suggest an 'easier way' then.

Johnny B Good

Re: Electric start for suitcase inverter generator by using its alternator as a BLDC motor?
On Friday, 13 July 2018 15:28:27 UTC+1, Johnny B Good  wrote:
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Do you have links to the graphs & specs of the units you're comparing?

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Likely no setting option other than by replacing a resistor.

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I did, a wacking great inductor. Inductor i needs to exceed capacitive i. A
 pair of MOTs in series would be my first thought.

I know you said it didn't work for you, but consider this. If inductive i e
xceeds capacitive i, the genny sees zero capacitive i. How then can it over
volt due to capacitance? IOW I suspect an unfound flaw in the implementatio
n somewhere.


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