Automotive electronics - Honda charging system

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This may not be the appropriate place to post about this.  If so, just ignore  
it, and my apologies.

Honda has a dual-mode charging system for US models.  When the headlights are  
on, or any other combination of things that increases the amp draw through  
the system to a certain point, the computer tells the alernator to put out  
14.4V, or thereabouts.  But at all other times the alternator puts out about  
12.3V.  This is done to increase gas mileage.

At my last oil change (2012 Civic), the dealer checked out everything,  
including the battery.  They said the battery was ok, but was only 57%  
charged.  It seems to me that this is a direct result of the charging  
algorithm.  Even if the battery was fully charged, which would be a resting  
voltage of just under 12.7V, if the alternator is told to output only 12.3V,  
then the battery will be providing all the needed current until it is  
discharged down to that level, which should happen fairly quickly.

My understanding is that lead-acid batteries don't do well being partially  
charged all the time, not to mention not having as many cranking amps  
available as you might need.  In fact, I replaced the original battery at  
just under three years.  Yet Honda has been doing this dual-mode thing  
literally for decades.  So perhaps I'm wrong about the effect of this system  
on battery life.

The odd thing is - if you want the car to charge the battery, you DO NOT want  
to shut off the lights, the fan, the radio, etc., because that will just  
lower the alternator voltage to 12.3V, which won't charge the battery at all.  
Instead, you want to turn on the headlights - because that will cause the  
alternator to put out 14.4V, which WILL charge the battery.  Can you spell  
counterintuitive?

So one option is just to get a charger, and charge the battery overnight  
maybe once a week.  But another alternative is to modify the current-sensing  
circuit so the computer thinks the lights are on even when they aren't, so  
the alternator will stay at 14.4V all time - just like every other car in the  
world does. But before going down that road, I need to be sure I understand  
what, if anything, this Honda system is doing to the battery because the  
modification, which is called the ELD bypass, is a real bear for my model  
car.

And in case you were wondering, it appears that this Honda system doesn't  
take into account at all the current charge state of the battery.

Well, I would appreciate some expert opinion on the effects of having the  
battery be partially charged all the time.  I've read several places online  
that this promotes sulfation.  But it's not clear.  It's also not clear  
whether a weekly full charge would undo the sulfation.

Thanks for any advice.


Re: Automotive electronics - Honda charging system
On Wed, 07 Dec 2016 11:21:51 -0600, Peabody

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At a constant 14.4V setpoint you risk overcharging the battery,
particularly in warmer climates/seasons.

The correct TC can be seen at...

<http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>

You may be able to buy an off-the-shelf unit to replace the Honda
original... depends on how the Honda is wired.
        
                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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Re: Automotive electronics - Honda charging system
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particularly in warmer climates/seasons."

Disagree. the most reliable cars I have seen generally charge at like 15.2  
when cold, tapering off with temperature of course.  

You are in Arizona, here it gets down to 0F so we need these batteries char
ged up, bigtime. And the less the battery is charged the higher the freezin
g point of the electrolyte.  

What you say might be alright for the climate where you are, but here even  
that 5W20 shi9t oil can get so thick it bogs the starter down, especially w
ith the better oil pumps in the newer cars.  

Another thing that might surprise you is that some cars actually pull more  
power to run than to start, a sharp contrast to the past. In a V6 you gener
ally have three coils that put out more firing voltage at more current than
 the old style V8, plus you have six fuel injectors whose current drain is  
not trivial.  

The regulation in the older cars when it comes to charging is that you woul
d lose too much water and have to keep adding it to the battery. With the s
ealed batteries this is not an issue. Of course technically they are more l
ikely to explode but I have not heard of it happening much. Plus the pressu
re they built up before the electrolyte re-absorbs the gases is really not  
more dangerous than the hydrogen they used to emit.  

I think Honda made a mistake doing that. Once out of factory warranty I wou
ld find the wire that controls this and make it put out the full voltage al
l the time. Again, the climate does matter. In Texas or whatever you are pr
obably fine, but in Wisconsin that is another story. You gotta have the sta
rter motor pull that sludge through the oil pump as well as fire ten amps w
orth of fuel injection just to get started. And after that ordeal for the b
attery then the alternator only half ass charges ? Ill conceived idea to sa
y the least.  

Another thing is that since the late 1980s, cars have had kinda shitty alte
rnators. My friend's brother in law had a car that needed a new one every t
wo years or so, and where they put it you had to damnear pull the engine. A
nd this was a GM product, I think the 3.4L "rat" engine.  

Fuck all that, gimme a 1967 Chevy.

Re: Automotive electronics - Honda charging system
snipped-for-privacy@gmail.com says...

 > Disagree. the most reliable cars I have seen generally
 > charge at like 15.2 when cold, tapering off with
 > temperature of course.

It will be next summer before I can test this, but there's a
"thing" attached to the negative battery terminal in
addition to the ground cable. Could this be a temperature
sensor for the battery?  Is the negative terminal the right
place to take this reading?  So far, though, if it's high
voltage, it's exactly 14.4V.  No variation.

 > I think Honda made a mistake doing that. Once out of
 > factory warranty I would find the wire that controls
 > this and make it put out the full voltage all the time.

Honda uses an Electronic Load Detector (ELD) that's located
in the engine compartment fuse box.  It's a strange looking
thing that has a slot all the way through it, and there's a
metal bar that goes through that slot.  The entire current
load of the system goes though that bar, and the ELD must
have a coil surrounding the slot.  The current induces a
corresponding current in the coil, and then some mystery
circuit in the ELD pulls down the 5VDC provided by the
computer via a pullup resistor so that the voltage indicates
the current load.  The switching point appears to be about
2.1V.  Below that, you get 14.4V from the alternator.

So the solution to this could be to just add a pulldown
resistor to that sending line so that it always reads below
2.1V, or perhaps a 2V zener to ground, or even three forward
biased diodes to ground would work.  You can't just ground
it because then the computer will throw a code and turn on
the check-engine light.

The problem is figuring out which wire it is, and getting to
it.

 > Fuck all that, gimme a 1967 Chevy.

Nah.  Modern cars are really nice.



Re: Automotive electronics - Honda charging system
On Wednesday, December 7, 2016 at 3:37:53 PM UTC-8, Peabody wrote:
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Modern "maintenance free" batteries can't tolerate that high a charging voltage - they'll gas too much and lose electrolyte.

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That "thing" is probably a hall-effect current sensor, my Spark EV had one and also had a similar charging regime.
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...

There is a fair amount around on the web about the Honda charging system:

For example <http://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article10%11&context=auto_pres .

The 12.3 volts does sound a bit low - that article states it should be 12.5-12.7V.  That is not enough to charge the battery but will maintain it at 100% SOC after it has charged.

The higher voltage setting is to be able to recharge the battery under conditions when it will get discharged somewhat.

The Spark EV even had a separate mode of operation when the car was new to condition the battery correctly during the first few weeks of its life.

kevin


Re: Automotive electronics - Honda charging system
Peabody says...

 > It will be next summer before I can test this, but
 > there's a "thing" attached to the negative battery
 > terminal in addition to the ground cable. Could this be
 > a temperature sensor for the battery?  Is the negative
 > terminal the right place to take this reading?

I wanted to follow up on my own post in case anybody sees
this in the future.  I still don't know what that "thing"
is, but its connector looked a bit crooked, as though it
wasn't connected properly, so I broke and remade the
connection.

And now everything is different.  Well, the high voltage
point is still 14.4V, but it stays there for a while after
the engine is started, which it didn't do before, and now the
lower voltage point varies between 12.8V and 13.2V, whereas
before it was always 12.3 or 12.4V.  Also, when I go downhill
with my foot off the gas, it shifts into 14.4V mode.  I
guess that could be some kind of regenerative thing,
although, you know, this is a regular engine, not a hybrid.

Anyway, since I make a lot of short hops, I still may need
to put the charger on it now and then, but it looks like
it's behaving a lot better than it did.

I just wish if the connection wasn't good it had turned on
the CEL and thrown a code of some kind.  If that had been
the case, this would have shown up at the dealership when I
bought the car, and I probably wouldn't have had to replace
the battery at three years.  I'm sure the connection has been
bad for the five years since I bought the car.

And by the way, a really handy thing to have is a little
voltmeter that plugs into the cigarette lighter socket, and
displays the current charging voltage continuously.  About
$6 on Ebay, or even less if you get one from China.



Re: Automotive electronics - Honda charging system
On Mon, 12 Dec 2016 15:44:27 -0600, Peabody

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It's at "ground", so best place for a sensor.  The positive terminal
can see short duration, but very high voltage spikes.

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[snip]

That would fit better with my TC data from the '60's when I was
designing alternator regulators...

<http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
        
                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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Re: Automotive electronics - Honda charging system
On Monday, December 12, 2016 at 1:44:36 PM UTC-8, Peabody wrote:
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This thread has provided me with a lot of helpful information.  I have a 20
16 Toyota Camry and the charging system has not been keeping up with infreq
uent use and short trips. As in the Honda, I think they are reducing altern
ator load to increase fuel economy.

The Camry does not appear to have a smart charging system. The battery volt
age reads 14.2 volts after a cold start but doesn't stay there for long. If
 restarted while still warm, the battery voltage is close to float voltage  
which would not replace the charge lost in starting. Another problem is the
 parasitic current drain which runs continuously.

Driving the car once every 7-10 days discharged the battery over a period o
f many months and the engine eventually failed to start.  The specific grav
ity of the battery showed empty.  After getting a jump start, the car ran n
ormally although I discovered later that the charge level of the battery wa
s being replaced very slowly.

I bought a Black & Decker 2A Battery Charger/Maintainer which eventually re
stored the battery to full charge.  The specific gravity now measures 1.285
. The interesting thing is that the full recovery took two weeks.

It looks like I will also have to connect the Charger/Maintainer periodical
ly or just leave it connected.  In Maintain Mode the voltage levels out at  
13.68 volts which should be a safe Float Voltage.

I also plan to buy one of the voltage monitors that plugs into the accessor
y socket to keep an eye on the battery voltage.

Re: Automotive electronics - Honda charging system
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How about getting a slightly smaller alternator pulley?

Cheers

Phil Hobbs

Re: Automotive electronics - Honda charging system
On Tue, 4 Jul 2017 15:52:53 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

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How does that help?  The voltage regulator is in charge of things.  


Re: Automotive electronics - Honda charging system
snipped-for-privacy@notreal.com wrote:
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...then re-adjust the regulator.


Re: Automotive electronics - Honda charging system
On Tue, 04 Jul 2017 17:35:18 -0800, Robert Baer

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Good luck with that.

Re: Automotive electronics - Honda charging system


It is, assuming there's enough alternator output for it to be in regulation
. Sounds like that's likely the problem.  

Cheers

Phil Hobbs

Re: Automotive electronics - Honda charging system
On Wed, 5 Jul 2017 05:11:15 -0700 (PDT), snipped-for-privacy@gmail.com wrote:


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(Personally I'd cobble up my own regulator ;-)

US 'CAFE' fuel economy standards are forcing car manufacturers into
Rube Goldberg 'solutions'...

Recently was provided a 'loaner' of a new Infiniti Q50 while my
ancient, 'real car' (12 year old) Q45 was in for service.

This Q50 had only a 2L 4-banger engine (provided by Mercedes no less).

At each traffic light the engine is STOPPED with a jerk, then
restarted... feels like a diesel start (compressed air ?) :-(

What a disconcerting piece of crap!

(I informed the dealer I wouldn't be buying any Infiniti product until
they came back to providing a honking V-8 again, like my Q45.  He
sighed, said he agreed.)
        
                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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Re: Automotive electronics - Honda charging system
On Wed, 5 Jul 2017 05:11:15 -0700 (PDT), snipped-for-privacy@gmail.com wrote:


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Doesn't to me.  It seems the charging system is trying to be too cute
to save .001MPG.

Re: Automotive electronics - Honda charging system
kt77 says...

 > I bought a Black & Decker 2A Battery Charger/Maintainer
 > which eventually restored the battery to full charge.
 > The specific gravity now measures 1.285. The interesting
 > thing is that the full recovery took two weeks.

 > It looks like I will also have to connect the
 > Charger/Maintainer periodically or just leave it
 > connected.  In Maintain Mode the voltage levels out at
 > 13.68 volts which should be a safe Float Voltage.

 > I also plan to buy one of the voltage monitors that
 > plugs into the accessory socket to keep an eye on the
 > battery voltage.

Sounds like your car has problems similar to my Honda.  I
think all the manufacturers try to get as much mileage as
they can, so they use the alternator as little as possible.
The problem is that the battery doesn't stay fully charged
that way, so it sulfates up and dies sooner.

I continue to try to deal with mine.  I've been using the
charger every week or so, but recently decided to try
driving with the headlights on all the time.  The alternator
puts out 14.4V all the time when the lights are on, and that
should keep the battery charged.  I shouldn't have to do
that, and I found a Honda TSB that addresses this problem
for 2012 Civics like mine.  They program new charging
parameters into the computer.  My car is out of warranty,
but I'm going to see if I can get the dealer to flash the
new firmware at Honda's expense since we know the fault was
there on delivery of the car.

I definitely recommend one of those votage meters that plugs
into what used to be the cigarette lighter socket.  It will
tell you the current charging voltage.

Basically, my understanding is that a lead-acid battery is
fully charged at about 12.6-12.7V, and that's what the computer
should keep it at.  You can get by with less, but at the
cost of shorter battery life.  But to keep the battery at
12.6V, the voltage regulator should NEVER go below
13.0-13.2V, and immediately after starting the engine it
should go to 14.4V for several minutes at least to recharge
the battery.  As of now, the only way I know to at least get
that is to turn on the headlights.  Oddly, turning on the AC
does not do that.



Re: Automotive electronics - Honda charging system
Peabody says...

 > Basically, my understanding is that a lead-acid battery
 > is fully charged at about 12.6-12.7V, and that's what
 > the computer should keep it at.  You can get by with
 > less, but at the cost of shorter battery life.  But to
 > keep the battery at 12.6V, the voltage regulator should
 > NEVER go below 13.0-13.2V, and immediately after
 > starting the engine it should go to 14.4V for several
 > minutes at least to recharge the battery.  As of now,
 > the only way I know to at least get that is to turn on
 > the headlights.  Oddly, turning on the AC does not do
 > that.

I just wanted to report that I was able to get my Honda
dealer to do the service bulletin 12-041 flash update that's
supposed to fix this problem for the 2012 Civic.  That will
be done tomorrow.

But I suspect that allowing the battery to be less than
fully charged, without doing anything about it, is a
deliberate Honda practice on all their cars to keep mileage
up.  If I understand how a battery and battery sulfation
works, there's no reason to ever have the alternator putting
out 12.4V, which my Honda does most of the time.  That would
let the battery drop to 12.0-12.2V, which is roughly 50%
charged, not fully charged.  And at that level it will
sulfate up and die much more quickly than if kept fully
charged.  So I suspect I'm still going to have to drive with
the lights on after the SB is applied.  But maybe it will
help some.  My voltmeter will tell the tale.

However, if keeping the battery at 50% does not cause
sulfation, then I'm wrong, and Honda is right.  But
everything I read says that's bad for the battery, and it
should be kept at 12.6V which is near 100%.  If anyone knows
for sure about this, please post here.



Re: Automotive electronics - Honda charging system
On Wed, 05 Jul 2017 10:48:10 -0500, Peabody

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There's a 'little' TC issue that must be met to ensure proper
charge...

<http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>

Also see my patents about alternator regulators.
        
                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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Re: Automotive electronics - Honda charging system
Jim Thompson says...

 > There's a 'little' TC issue that must be met to ensure
 > proper charge...

 > <http://www.analog-innovations.com/SED/AlternatorRegulat
orTC.pdf>

Thanks very much.  Well I don't see anything on your graphs
anywhere near Honda's 12.4V.  It looks like you have an
absolute minimum of 13V even at high temps.  And I suspect
if my Honda followed that, there would be no problem.

Charging voltage aside, is the "off" voltage of a fully
charged battery also temperature dependent - assuming you
give it time to settle?  So would the 12.6V I've been using
as a fully-charged voltage be lower at higher temps?
Is there a graph for that?



Re: Automotive electronics - Honda charging system
On Wed, 05 Jul 2017 13:05:46 -0500, Peabody

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I've never actually measured that.  The graphs show the drive voltage
necessary to supply current TO the battery, so I suspect, but don't
know absolutely that the battery should show voltage equivalent to
that IF at the proper temperature.
        
                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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