Automotive electronics - Honda charging system

On Wednesday, December 7, 2016 at 3:37:53 PM UTC-8, Peabody wrote:
> jurb6006@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.

Modern "maintenance free" batteries can't tolerate that high a charging voltage - they'll gas too much and lose electrolyte.

> 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.

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

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

For example <http://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1011&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

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.

On Mon, 12 Dec 2016 15:44:27 -0600, Peabody
<waybackNO584SPAM44@yahoo.com> wrote:

>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?

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

>
>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.
>
[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      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

On Monday, December 12, 2016 at 1:44:36 PM UTC-8, Peabody wrote:
> Peabody says...
> 
> I wanted to follow up on my own post in case anybody sees
> this in the future.
>

This thread has provided me with a lot of helpful information.  I have a 2016 Toyota Camry and the charging system has not been keeping up with infrequent use and short trips. As in the Honda, I think they are reducing alternator load to increase fuel economy.

The Camry does not appear to have a smart charging system. The battery voltage 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 of many months and the engine eventually failed to start.  The specific gravity of the battery showed empty.  After getting a jump start, the car ran normally although I discovered later that the charge level of the battery was being replaced very slowly.

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.

>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. 

How about getting a slightly smaller alternator pulley?

Cheers

Phil Hobbs

On Tue, 4 Jul 2017 15:52:53 -0700 (PDT), pcdhobbs@gmail.com wrote:

>>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. 
>
>How about getting a slightly smaller alternator pulley?

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

krw@notreal.com wrote:
> On Tue, 4 Jul 2017 15:52:53 -0700 (PDT), pcdhobbs@gmail.com wrote:
>
>>> 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.
>>
>> How about getting a slightly smaller alternator pulley?
>
> How does that help?  The voltage regulator is in charge of things.
>
...then re-adjust the regulator.

On Tue, 04 Jul 2017 17:35:18 -0800, Robert Baer
<robertbaer@localnet.com> wrote:

>krw@notreal.com wrote:
>> On Tue, 4 Jul 2017 15:52:53 -0700 (PDT), pcdhobbs@gmail.com wrote:
>>
>>>> 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.
>>>
>>> How about getting a slightly smaller alternator pulley?
>>
>> How does that help?  The voltage regulator is in charge of things.
>>
>...then re-adjust the regulator.

Good luck with that.

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.

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

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

Cheers

Phil Hobbs