Tesla Batteries

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Going off the grid (not me not now but...) we are looking at Tesla batterie
s for energy storage. These would be charged from solar panels.  

It is reasonable to assume the panels are not going to charge at the rate o
f an AC operated 240 volt one, is that alright ? Will they charge properly  
?  

Of course there is the option of taking them initially to the station and c
harging them there, but where this is going there are not going to be any c
harging stations. If a float charge can be maintained it would work. The re
serve would certainly be there and it would be a matter of replacing whatev
er energy is used.  

Is this good for the battery though ? I mean from what I read it will take  
a towmotor to install the batteries so we can't have them failing soon.  

Luckily the whole thing is mobile and under its own power. It will be a tru
ck converted to a camper, but it is not going to live at a campground. Plus
 I doubt that you can pull enough power from a campground to charge one. Of
 course the proper fittings can be installed and the thing driven to a char
ging station but we do not want to HAVE TO do that.  

I remember some NiCds that would suffer if they are not run down and rechar
ged periodically. Are these batteries like that ?  

The other question is if they suffer from self discharge - much. I don't kn
ow, there could be more than one in parallel.  

We thought about a 300 volt system but that is nixed for now for a few reas
ons. However that could change depending on what kind of information I glea
n about this whole matter.  

I might have to actually build a charger, if so I would have to figure out  
what I can and can't do. Constant current is no problem if that's what's ne
eded. But what would be the minimum current ?  

If the batteries are low in voltage, the current would only have to be at a
 slightly higher voltage than the state of charge dictates, but then can I  
taper off when it nears full charge ?  

And if we simply can't muster the "rated" charging current with the solar,  
what are the consequences ? If some other type of battery would be more sui
table that can be worked in.  

I will not say cost is no object, but we know this is not going to be cheap
. And we don't plan on really draining that much. There will be A/C but tha
t will run of a generator. Want cooling go get some fuel for that. It is ho
wever not a necessity. We need the necessities to remain away from the grid
 practically indefinitely. For example I am sure a propane stove would be n
ice because electric sucks, plus is less cost effective. But there would be
 electric alternatives. Intermittent use of things like a toaster oven, ele
ctric skillet, microwave and all that will be in there. We are aware of wha
t kind of power that uses, so propane, as long as it is plentiful or nearby
 would be the norm.

However we want to avoid an absorption refrigerator and would prefer to run
 one on 120 volts. There wouldn't be much running off the inverter but what
 does will want amps. Al the lighting will be low voltage LED, even fans. J
ust things with a compressor are the problem there.

I have already did some web searching but the specific numbers I want seem  
to be elusive. For example I could calculate by what the charger pulls at 2
40 volts in the garage normally and get an idea. But there are specific tha
t will be lacking unless I can get the whole setup and test it. That would  
be impractical, we are not buying a whole Tesla, just some batteries. Thus  
the question about self discharge, used batteries might not quite have the  
capacity as new ones, so two of them might be better. That is of course if  
they don't kill each other.  

Any advice appreciated. (well almost)

Re: Tesla Batteries
On 1/7/2019 12:28 PM, snipped-for-privacy@gmail.com wrote:
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You obviously don't have a clue.  That's ok, get some professional  
system advice.
Surely there's an off-grid newsgroup with actual relevant experience.

DO NOT COBBLE TOGETHER YOUR OWN BATTERY CHARGER.
Batteries are the most expensive part of the system.  You want to make
them last as long as possible.  Get a charger configured to interface
with your EXACT source and battery configuration.

DO NOT BELIEVE THE POWER CONSUMPTION RATINGS ON THE PRODUCT STICKER.
Do the math with real numbers.
An electric heater with 1200W on the panel can reasonably be expected.
to consume 1200W.  Most other things have non-unity power factor and can
have a significant effect on the numbers you need to calculate.
Don't expect to be able to use more than half of your battery capacity.
Solar panels are rated for noon on a summer day with perfect solar tracking.
On a rainy winter day, you don't get much at all.

A system that keeps you up and running thru a week-long blizzard
is gonna cost you WAY more than you think.
Don't try to plan it a piece at a time.
Determine the exact requirements.  Get a quote on a professionally
installed system.  Start with the most expensive parts and see if
you can whittle it down to full DIY, or whether you can effectively
purchase some of the system parts.

Cobbling together a system that doesn't meet your needs is a big
waste of money.

Re: Tesla Batteries
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That is not advice.

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system advice. "

That is advice. Of course that is why I am here. I figured someone might kn
ow about these things.  

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I really want to avoid that like the plague. I know there is more to it tha
n a constant current source.  

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Do the math with real numbers. "

I know about power factor. The problem with real numbers is obtaining them.
 I tend to figure worst case. So he has this fridge in mind that is rated 3
.5 amps running and 6 amps to start. I think it reasonable to assume that t
he starting current is going want close to the 720 watts, but in run it is  
not going to be 400 watts. Thing is, worst case scenario just figure the 40
0 and enjoy whatever headroom.  

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 cost you WAY more than you think. "

I am not sure what this guy thinks it is going to cost, but if he is not af
raid of buying Tesla batteries I doubt he intends to be penny wise and poun
d foolish.  

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installed system. "

Might, or maybe from one of the places that sells them. But it seems to me  
that whatever they put together could be enhanced.  

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you can whittle it down to full DIY..."

Sounds like a plan.  

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 money. "

That's why I'm here.

Re: Tesla Batteries
On 1/8/2019 3:59 PM, snipped-for-privacy@gmail.com wrote:
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There's not "more to it"!  You absolutely do not want a constant current  
source under any circumstances.

I know only what I've read from other people who probably don't know what's
actually going on in a Tesla charger either.
I'd suggest that the charger has some minimum power requirement just
to make the electronics and safety features of the charger work.

Unless you have some inside proprietary information, I'd suggest you use the
TESLA charger designed for that exact battery.  That means you're gonna need
a way to get sunlight into whatever voltage and current the charger wants.
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Vendors misrepresent to generate competitive advantage.

Get a Kill-A-Watt meter and measure stuff.

I made a measurement on your behalf.
A 100W-equivalent LED light bulb measured 16W and 16VA.
A different 100W-equivalent LED light measured 16W and 20VA.

Inverters are rated in W and VA.  That 25% extra VA can make a big
difference in what your inverter can tolerate.  Depends on the degree
of misrepresentation the inverter vendor can tolerate.

If you add up all your demand, you'll find that you cannot afford
a solar system that lets you run everything at once.
That gives you some interesting problems.
What do you want to happen if you're running the coffee pot and the
refrigerator clicks on and overloads the system?
Do you want your power system in a limit-cycle oscillation when the
propane heater is trying to start?
What do you want to happen when it's early sunny morning and the  
batteries are flat?
Is that different from what happens when it's cloudy out?
You will decide to have a backup generator.
How are you gonna predict when to run it?
Do you want it to run at 7AM if the day is expected to be sunny? cloudy?
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I waste a LOT of time helping someone with that attitude.
He ventures into areas where he hasn't a clue and can't be dissuaded by  
facts.
He thinks he can do everything better than the professionals.  I'm  
always digging him
out of holes he got into.
Reading your posts over the long term suggests that you two
should meet.

If you stick with an experienced vendor, it's likely that you won't be  
able to do a lot better.
I predict that you'll decide you can do it cheaper.  Maybe you can, but I've
got experience with people who try to do that, including me, and have  
decided that it's often a fool's errand.

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I've never pulled the trigger, but I've pondered off-grid and solar in
scenarios from staying put and going mostly off grid all the way to
post-apocalyptic existence.

The first question to answer is why you're doing it.
Exactly what are you trying to accomplish?
It's easy to get tunnel vision and ignore the possibility that a
minor change in the objective can make a BIG difference in the
execution.
"Just because I can" is best left to areas where you have significant
experience.

One important thing to consider is, "how easy is it for someone to vandalize
or steal my solar system?"  Most people ignore questions like this
because they think the probability is low.   Probability makes good
sense when sizing a sewer system or writing an insurance policy.
In an individual situation it's either 0 or 1.  There ain't no
in-between.

What are the parameters of your situation?
If your scenario predicts easily available propane, you might consider
running everything possible from that.  If your scenario predicts
the failure of civilization and roving gangs plundering everything
in sight, maybe you won't have propane...or solar panels when they
get finished with you.

In a propane situation, you may decide that your best option is
a bank of 12V Lead Acid batteries and a small solar system
and inverter.
Maybe 48V, but that creates portability issues for devices.
Maybe a propane powered generator.

My attempt here is to suggest that, how you charge a Tesla battery,
is WAY down your list of issues to resolve.

In my case, I couldn't come up with any scenario that resulted in
lower energy costs.  Yes, there are people who have favorable grid power  
buy-back
situations...until they become no longer available.  That didn't work  
for me.

http://www.apricus.com/html/products.htm

There are lots of sources for info on solar insolation.
This is one such
https://www.nrel.gov/gis/solar.html

I've seen charts that disclose just how much solar energy you can get
by month, on average...but you still need SIGNIFICANTLY more to ride out
cloudy periods.

"insolation " is your keyword.

Don't ignore wind.  If you have it, it can be a major addition to
power, especially at night.

I'm a believer in simulation.
Go out to the breaker box and turn off all except one 15A circuit.
Run some extension cords to get everything you use running off that
circuit.
See how you feel after a month of that.

If you have a smart meter, you can probably put an IR sensor on that
and measure the time between light pulses.  When the time gets shorter
than the duration that represents the maximum power you'll have  
available, sound a horn.
A short horn blast represents an excess that you might be able to ride out
for a short time.  A continuous horn says, "turn something off."

I've helped engineer small combination wind/solar systems to put
on mountain tops.  Believe me, it's WAY more complex that it seemed
at the start.

Are we having fun yet?





Re: Tesla Batteries
On Tuesday, January 8, 2019 at 6:59:53 PM UTC-5, snipped-for-privacy@gmail.com wrote:
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know about these things.  
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han a constant current source.  
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m. I tend to figure worst case. So he has this fridge in mind that is rated
 3.5 amps running and 6 amps to start. I think it reasonable to assume that
 the starting current is going want close to the 720 watts, but in run it i
s not going to be 400 watts. Thing is, worst case scenario just figure the  
400 and enjoy whatever headroom.  

I don't think the issue is power factor.  The issue is knowing what the act
ual consumption is.  You seem to be aware of that.  Why can't you measure i
t?  There are no shortage of power measuring devices around.  


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na cost you WAY more than you think. "
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afraid of buying Tesla batteries I doubt he intends to be penny wise and po
und foolish.  
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e that whatever they put together could be enhanced.  
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of money. "
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I don't know what pitfalls you may encounter in tapping the battery for the
 DC, but the charging side of things seems rather simple.  

This is not likely the best place to get advice since no one here has done  
anything like this.  "Rich Rebuilds" is the closest to someone who has done
 what you want.  In particular I would dig about for the video on the guy w
ho shoved the 100 kWh battery into the sports car.  There would be some goo
d info there and you might try contacting some of the people in the video.  
  

  Rick C.

  -- Get 6 months of free supercharging
  -- Tesla referral code - https://ts.la/richard11209

Re: Tesla Batteries
On 01/07/2019 03:28 PM, snipped-for-privacy@gmail.com wrote:
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Some texting bitch wrecked my first Volt about two year ago, if the  
insurance company had let me keep the hulk I'd ship you that one to play  
with!

You can pick up 48V 45 ampere/hour surplus individual pack modules off  
eBay relatively cheap, tho (it takes about eight of these to make a full  
pack for the car)

<https://www.ebay.com/itm/2012-Chevy-Volt-Battery-2kWh-pack-Solar-Golf-cart-/223232038949




Re: Tesla Batteries
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eBay relatively cheap, tho (it takes about eight of these to make a full
pack for the car) "

We are still in the figuring out the need stage. Part of it can be changed, like a DC fridge is alot more expensive and usually too small, but a bigger invertor and a bit more battery ? Might be worth it.  

Those individual pack modules, from what ? Tesla or something else ?  

Re: Tesla Batteries
On 01/08/2019 07:02 PM, snipped-for-privacy@gmail.com wrote:
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a salvage Chevrolet Volt, a la:

<
https://d2t6ms4cjod3h9.cloudfront.net/wp-content/uploads/2014/12/CRASH2a.jpg


"It will buff out"

Re: Tesla Batteries
On 01/08/2019 07:45 PM, bitrex wrote:
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I've always wanted a compacted compact car:

<
https://www.plugincars.com/sites/default/files/volt-crash-1.jpg


Re: Tesla Batteries
On 09/01/2019 00:45, bitrex wrote:
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https://www.youtube.com/watch?v=Z4fBbhyzE9A


Cheers
--  
Clive

Re: Tesla Batteries
On 01/09/2019 06:46 AM, Clive Arthur wrote:
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Looking at the Volt wreck I would say....Ah! You're low on windshield  
wiper fluid there's your problem

Re: Tesla Batteries
On Mon, 7 Jan 2019 12:28:49 -0800 (PST), snipped-for-privacy@gmail.com wrote:

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Forget that idea.  Assuming you mean the Tesla PowerWall 1, 2, or 3,
these were not designed to power anything.  They were designed to
reduce your peak power usage (time of use load shifting) thus saving
you money on your electric utility bill.  

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Really?  Solar panels power a charge controller.  It's the charge
controller that charges your battery.  Misdesign the charge controller
and say goodbye to your battery.  There are many more ways to kill a
big battery than there are to use it properly, so be prepared to do
some careful shopping, designing, and building.  Trial and error is a
really bad way to design a charge controller.

Also, you'll need to deal with various electrical safety standards.  I
don't have any idea what is in fashion in the UK, but in the
Trumpland, we have NEC Article 690.  This is old, incomplete, but is
the most readable copy I could find online:
<http://www.energy.gov.bb/web/component/docman/doc_download/71-article-690-solar-photovoltaic-pv-systems
Many of the safety features, such as the rapid shutdown and
disconnect, can be complexicated and expensive.

Unfortunately, my favorite alternative power magazine ceased
publication last month after the deaths of the owners.  The online
archive of back issues are planned to be available eventually.
<https://www.homepower.com/about
<https://www.homepower.com
Meanwhile, the web site is full of relevant articles and information.
I suggest you dig through the "project profiles" for design examples
worth stealing:
<https://www.homepower.com/solar-electricity/project-profiles

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You probably won't appreciate this, but unless you have money to burn
on an over-designed monster system, you will find that going off grid
involves some substantial lifestyle changes and careful energy
management and accounting.  Most off-grid failures can be attributed
to the owners unwillingness to grind the numbers and make any
necessary changes.  I suggest you delay designing your system and
instead spend some time carefully measuring your current power
consumption and calculating your future off-grid power and storage
requirements.  Also, consider that the further north you live, the
more difficult it is to build a usable solar power system.


--  
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: Tesla Batteries
On 01/08/2019 01:32 AM, Jeff Liebermann wrote:
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e.g. this is the size of the array required to supply the energy needs  
of a small organic farm near me (Boston area); a modest single-family  
two-story farmhouse, large barn, and a couple other associated  
out-buildings on about 20 hectares of farmland/fields.

<https://imgur.com/a/ZDjSB9T

five 25 square meter panels mounted on sun-tracking mounts, a 5-10kW  
array, maybe.

Re: Tesla Batteries
bitrex wrote...
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 That sounds more like a 15 to 20kW system, or about 2x larger
 than mine.  My roof annually generates enough power for my
 power-hungry house (including electric hot water and 5kW heat
 pump to heat house above 40-deg F).  Maybe a system 2x larger
 could handle a small farm.

 BUT, given cloudy dark days and winter, I absolutely depend on
 banking my extra summer power into the grid, with net-metering.
 I use average 30kWh.  If off-grid, I'd want at least 10 days of
 backup, or a 300kWh storage system.  Smaller ones need not apply.


--  
 Thanks,
    - Win

Re: Tesla Batteries
On 01/08/2019 01:32 PM, Winfield Hill wrote:
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OP could get a Tesla and an array like yours and use the array to charge  
the Tesla. Then run an inverter off the Tesla to power the home when not  
driving it.

Then you get both an off-grid power solution AND transportation, hey hey!

Re: Tesla Batteries
On Thursday, January 10, 2019 at 11:46:21 PM UTC-5, bitrex wrote:
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Where do you get any power from the Tesla other than the 12 volt lighter sockets?  Oh, yeah, they also have some USB sockets.  

  Rick C.

  +-- Get 6 months of free supercharging
  +-- Tesla referral code - https://ts.la/richard11209

Re: Tesla Batteries
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Damn at looks big. You say 10 KW ? Hmmm. good reason for the A/C to be on the generator for sure.  

Re: Tesla Batteries
On 08/01/2019 06:32, Jeff Liebermann wrote:
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You have me interested now. I thought in the USA peak power load was  
typically in mid afternoon when aircon was at full stretch and by  
implication solar panels also at peak output. Surely the purpose of a  
Tesla power wall *is* to store any excess solar power to use later in  
the evening when the sun has gone down (rather than dumping it into the  
hot water immersion heater - as is common in the UK). A quirk of the  
feed-in-tariff is that you get paid a premium rate for half of what you  
generate no matter what you do with it (insane).

ISTR they come in 12kWhr blocks and are notable for being able to  
withstand being installed outside in the cold (UK never below -15C).

What is the peak discharge rate that they can cope with in practice?
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In the UK you would also have to worry about the battery being destroyed  
during the short grey winter days. There has been less than 10 hours of  
sunshine since 1/1 and around 8 hours of daylight. The sun doesn't pack  
much punch when it barely gets 14 degrees above the horizon.

It is worth pointing out that "professionally" designed active radar  
signs in the UK "please go round the (dangerous) bend" routinely destroy  
their batteries every winter. And they are a total waste of time - they  
work brilliantly in mid-summer but are dead in the water a couple of  
hours after sunset in winter and on every frosty winters morning!

A neighbouring villages cricket pavilion has a solar powered off grid  
system (because the cost of running mains to it was prohibitive). It  
seems to work OK but mainly because they only use it in summer.

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There are plenty of companies offering solar power systems in the UK but  
you have to be careful some are scam artists with incredible (and I use  
the word advisedly) predictions of customer savings on electricity bills  
that somehow never materialise. Likewise for ground source heat pumps.
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The only times I looked at setting up an offgrid supply it turned out to  
be much cheaper to have a pair of big lead acid SLA's and charge them  
off site weekly. It was an order of magnitude cheaper than solar power -  
granted solar PV prices have come down a long way since then.

--  
Regards,
Martin Brown

Re: Tesla Batteries
On Tue, 8 Jan 2019 08:50:22 +0000, Martin Brown

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No wonder.

Take a look at
https://en.wikipedia.org/wiki/List_of_cities_by_sunshine_duration
For UK in December, there are about 50 hours sunshine, i.e. less than
2 h/day. Even mounting the panels vertically on the southern wall
doesn't give a lot of energy in December.  

Also remember the air mass (AM) losses due to the low sun angle, when
only a half or quarter solar intensity is available. Thus a "100 W"
panel will produce 25-50 W in December even with optimal orientation
and this is available only 2 h/day on average.


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Re: Tesla Batteries
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That's another question. I doubt they like to run into a short circuit.  


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