Automotive electronics - Honda charging system

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

The correct TC can be seen at...

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

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| 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     |

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.

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Don't the headlights stay on all the time (when in the auto mode) on most modern cars and trucks? That should be enough load to keep the charge voltage normal.

I wouldn't know... my car is 11 years old and my pick-em-up truck is

16 ;-) Neither has "daylight headlamps" though the car does sense dark and turns them on. ...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     |

No. The daytime running lights, at least on my car, use a lot less current than full headlights, and the voltage stays at 12.3V. The running lights appear to use the high beam filaments, but at much lower than normal current.

I just received my cigarette lighter voltmeter, and on a run downtown and back it never came off low voltage unless I turned on the headlights, even over 60mph and with the heater fan on. I assume the rear window defroster might switch it to 14.4V, and perhaps the A/C. But otherwise, if you're driving around during the day in wintertime with just the running lights on, it's going to be 12.3V all the time. And that means the battery isn't fully charged. Ever.

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.

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.

Nah. Modern cars are really nice.

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Yeah, my car is 16 YO and PU is 12 and the voltage is always around 14 volts. The batteries last about six years.

I must always remember to unplug the GPS as the cig lighter outlets are always on.

Seems like a bad idea to let the battery go down to 12.3 volts while running.

Unless you run with the headlights on all the time. Sounds like a designed by monkeys episode.

Most modern cars seem to have a white LED "light bar" either surrounding the headlights or in the fender somewhere for the daytime running lamps. That probably doesn't draw too much current.

Then the headlamps switch on after dark, and they're usually LED, halogen, or some kind of xenon HID.

My less-than-1-year-old Volt has LEDs for the low beams and warmish orange-yellow halogens for the high beams. I often get people flashing me thinking my low beams are actually my high beams. The LEDs in combination with the halogens are like rays from the Almighty himself.

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

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 .

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

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.

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

[snip]

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

...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     |

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.

How about getting a slightly smaller alternator pulley?

Cheers

Phil Hobbs

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

Good luck with that.

...then re-adjust the regulator.

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.

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

Cheers

Phil Hobbs