Boiling battery

And the saga continues, the conclusion.

1991 Laser, 1.8L

Step 1

  1. Old battery was a Delco, bought it 2002
  2. Second battery, had a Mopar label, but suspect it was Exide, about three years of life. Both batteries spewing liquid, much corrosion on car. Just replaced battery with brand new Exide battery, over rated for this vehicle, more CCA (525, car requires 430).

What I found on the drive home. Install of new battery, before cranking engine, voltage is 12.6 volts. After cranking engine with, engine running, 14.36 volts

2 minutes after starting, battery voltage is 14.19 volts. With a Fluke DVM connected to the battery, for 27 Km, battery voltage varied between 14.09 (at a stop light) to 14.21 at 70Km per hour, no load beyond engine draw. At idle with full current draw (rear window defog, head lights and blower) battery voltage was 13.86. Idle voltage with no current draw (beyond engine and driving lights) was a battery voltage of 14.09 volts. Time to recovery from a full load idle was about 1 min. Air temp was about 25 degrees C. It should be noted that I was also monitoring the "sense" voltage (on a second meter) at the alternator (voltage reg input), and that voltage was about .5 volts lower, but followed the battery voltage, and never changed beyond always being about ,5 volts less than the battery. For 27 Km the monitored battery voltage never exceeded 14.35 volts.

Step 2 Attached a third DVM, to monitor the current output of the alternator (250 amp shunt installed in series with the output). With the day time running lights and, always on, side markers, disabled (removed fuses), the current from the alternator was 15 amps (seems high to me). Moved the shunt to the battery, current into the battery was 5 amps at start but was decreasing to 4.16 after about 15 minutes (idle speed). Battery voltage was now about 13.70 volts. Manual says when the regulator operates above 60 degrees C that the reg voltage is 13.4 to 14.6. The alternator housing containing the regulator was to hot to hold your hand on. At no time during any of this testing did the battery voltage exceed 14.5 volts. And for the record, the "key out of the ignition" current draw was, 125 milliamps. So, unless I can find some other problem, my best guess for an answer is, "two bad batteries, with the same fault".

Test instruments tell me that the system is operating normal, the only variable was the battery. After about 50Km of driving there is no sign of fluid leakage from the battery. At no time did any of the three batteries feel warm to the touch. The second battery (Mopar) had a specific gravity reading in the "white " zone between green and red, but this could have been because we had added water. The first battery was sealed and un testable.

I now know more about batteries and charge systems than I ever wanted to know. Now I just need to know how to stop all the battery acid corrosion. I have washed everything with baking soda and water, but it still seems to be corroding.

Reply to
nirodac
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"Now I just need to know how to stop all the battery acid corrosion. I have washed everything with baking soda and water, but it still seems to be corroding."

Zinc phosphate wash and rust encapsulator of some kind. I just ordered a bunch of this from Eastwood. The acid cleaned the exposed metal on your car and opened it for corrosion.

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Reply to
simpleton

There is one thing to check that you didn't mention checking. While all of your voltages and things seem to be in an acceptable range, you did't mention "AC ripple voltage".

In other words ... how much AC is coming out of the battery terminal of your alternator. As a person who has previously rebuilt alternators, I have seen this many many times. The battery light on the dash goes off, the voltage is good, etc etc but the battery boils over or goes dead and the person can't find the problem.

Sometimes this problem can be diagnosed just by listening. A high pitched "whine" is sometimes emitted (that people often think is a bad bearing or belt). My suggestion is take the alternator off and have it tested. I realize that on some cars this is easier said than done, but I really think this is where you'll find the problem. I have had bad batteries out of the box, but never 2 in a row with the same problem.

Reply to
Walter

Another thought: Is it possible that you are overfilling the distilled water level on the battery? On most you need to keep the water BELOW the fill neck in each cell. If you do not then the water will bubble over and cause what you are seeing.

Bob

Reply to
Bob Shuman

Thanks for the suggestion. After reading your post, I went outside with my Oscope, and checked for ripple. There is about 50 mV (millivolts) of AC ripple at idle, as measured at the battery. There is also a spike every once in a while of 258 mV. Output voltage at the battery was 14.0 volts. The battery was connected for all these tests.

I think this proves the system is working. The spike is probably the regulator cutting in and out.

Thanks again.

Reply to
nirodac

Battery number one was sealed, couldn't add water Battery number two was never filled above the bottom of the neck. There were 2 slots cut in each neck that extented about 1/2 inch higher than the fluid level. This would allow for out gasing.

Reply to
nirodac

Or a diode that is failing. Turn the headlights on and retest.

Reply to
Walter

OK, retested the alternator (as measured at the battery) the amount of ripple, and the height of the spike did not change when I loaded down the alternator with the headlights, fog lights and RW defogger. The spike is random and not at any given spot (time wise). The ripple was, under heavy load, 124mV and the spike was 165mV above that. These numbers are slightly off from the other post, might be due to the high temp the other day as opposed to the temp this morning. Even though the instruments tell me all is OK, I'm still not comfortable with the results. Two batteries with the same boiling problem is very rare.

Next project, nutralize the acid damage!!

OBTW. I measured the voltage on the old battery. It was about 9.6 volts. With a shorted cell that would mean that the other cells were being overcharged.

Reply to
nirodac

In this case, then, I would guess you have a burned phase winding in your alternator's stator or the regulator is stuck at a certain point (doesn't allow the voltage to go up or down) so while it seems okay at

14.4 volts (or whatever number you said it was at), with a fully charged battery, it may not need the alternator to put out as many amps as it is.

I didn't have an ocilloscope in my alternator shop so I never saw/measured spikes from the regulator cutting in and out ... but it seems like once the regulator has an ignition input, it should stay on until such a time that it loses that ignition input (when the engine is turning over and when you shut it down). If it really is the regulator cutting in and out, I would guess that is the problem.

I don't know what alternator your car has, but most alternators these days are internal regulator, so your alternator is still bad.

As for acid problems, I would wash it all down really good with baking soda and water ... then inspect all hoses and wires for holes and exposed copper (in the case of the wiring). Make repairs as necessary .. then tape all the wires up to further protect them from continued exposure to acid.

If the alternator isn't going to take 4-5 hours and dropping a subframe to get it off, I would take it off and get it checked by a rebuilder, too ... just for peace of mind.

Reply to
Walter

Well if I had a bad phase winding, either shorted or open, I would think the scope would show two missing pulses. All six peaks are there, in sequence.

or the regulator is stuck at a certain point .

Not quiet. I bench tested the VR, it does cut out at about 13.6 volts, and turns on at about 14.2 volts. This voltage varies depending on the regulator temperature. And this VR does that. As well the voltage does vary within spec, depending on the load.

I don't know what the car needs to operate, the best (lowest) measurement I got was that the alternator was producing 13 amps, 5 ended up in the battery (the manual says, that at 5 amps, it'll take about 3 hours to charge the battery, so I guess the car needed the other 8 amps (ignition coil, injector, various relays, etc.).

Your pretty much correct, but, Once the voltage reaches 14.2 volts the requlator should cut out, when the voltage drops to 13.6-13.8, the regulator should turn the alternator back on. With a 13 amp draw, the battery voltage would drop really fast to 13.6-13.8 volts, were the VR would turn on again. Turning on the armature would cause a spike.

Yes, the regulator is built into the alternator, has three leads, Battery output, Ignition input, and battery voltage sense. I do however think the alternator/regulator is OK. All the numbers are in spec. The scope shows all 6 pulses are pressent, and the spike is hardly an issue at only .150 volts.

Yes, very good advice. and also seal the exposed bare medal with an anti rust agent.

This one is real easy to remove, takes about 15 minutes to get it out of the car, but I'm not sure a pro alternator shop could tell me anything I don't already know. I already have more equipment for testing an alternator than the manual describes for the OEM shop. Output voltage is 14.2 volts, that won't boil a battery Output current varies, depending on load. Although maybe a little high at idle, but I can't confirm what that number should be.

Thanks for your input you obviously have a good under standing of this technology. I always find it great to bounce ideas off of someone else who actually nows what he is talking about.

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Reply to
nirodac

The regulator is the only thing that controls the alternator's voltage, and overcharging is the only way to boil a battery, so the cause has to be related to it. You are probably more aware of this than I am, but electronic outputs can latch up under the right (or wrong) conditions. The cause could be a thermal fracture in the internal PC board, or a weak wire bond in an IC. Something is causing it to go out of spec, and unless you are willing to drive around with half a dozen strip recorders in your car, I doubt you will ever see it. If you have ever seen your lights vary in intensity when driving at night that would be a good indicator. Also having to replace lights more often than every five years. Replace the regulator and see.

This is a bit of a stretch, but if the rotor brushes are worn out the alternator could run away under light loads. The rotor can become magnetized, and the regulator grounds out the rotor windings to prevent runaway. Like I said, a bit of a stretch.

New brushes, bearings, and regulator. Alternators are easy to rebuild, and on the Laser it is fairly easy to get to.

HTH Gyz

Reply to
Gyzmologist

This is a rebuilt alternator. Brushes and bearings are good. Looks like it was a good rebuilt, not just a back yard special. I drove about thirty Km with meters, not chart recorders, attached to the alternator, and nothing, 14.2 volts was the max. On the other hand, the last battery appears now to have a shorted cell, shows 9.5 volts. But it did measure 12 something a month ago.

I agree that it can be a thermal problem or vibration issue, but even after the alternator got hot, the VR step down a small amount, in it's output voltage, as the service manual describes.

After about the equivelant of 50Km, there appears to be no out gasing or liquid around the battery.

Looks like the VR provides a ground to the rotor to energize it. No ground, no output

At what voltage would a battery boil. I could install a sample and hold latch that would detect the highest voltage detect in a given period.

Reply to
nirodac

I wouldn't go so far as to say alternators are easy to rebuild ... but there are far more complicated processes.

The problem with rebuilding alternators is finding someone to sell you the parts (I sold parts to anyone who wanted them while I was rebuilding alternators) ... then you have to wonder if you are ruining the parts before you even get them in the unit. The other thing is if you find someone to sell you parts, it usually costs more for the pieces than it does to buy the whole unit already rebuilt at Pep Boys or somewhere like that (not that I recommend them for anything other than motor oil and spark plugs).

Many people tried rebuilding their own stuff only to bring it to me in a bucket or a box to be fixed and reassembled. They could've saved a lot of money and time by just bringing it to me in the first place.

Reply to
Walter

You're probably right, it is not as easy as it seems. I used to turn wrenches for a living, so for me it would be easy. Personally I think it is better to get the original rebuilt by a local shop than to purchase a rebuilt one from Pep Boys or Autozone. But that's me.

Reply to
Gyzmologist

There used to be a time when rebuilding alternators was easy ... ie Delco "SI" series alternators. Things aren't that easy anymore. In almost every alternator these days, some soldering is necessary. On the surface it's pretty easy, but most components are heat sensitive. Trying to solder without a carbon tipped soldering iron is asking for it (the carbon heats and cools quicker, making less heat in the components themselves).

Personally, I like to think the units I rebuilt were better than the ones that came from local stores and were even cheaper most of the time. People wouldn't go for it, though, because apparently they thought I got all my parts free of charge and was just ripping them off. The reality is they didn't know what they were buying from that local store except a "lifetime warranty" that is really meaningless. It is and was their money, though.

Reply to
Walter

"The reality is they didn't know what they were buying from that local store except a "lifetime warranty" that is really meaningless. It is and was their money, though."

The warranty is next to worthless when your daily driver is down and they don't stock you unit. 50 cans of Bondo on the shelf but not a single alternator for an Eclipse turbo in the entire state.

Current plan is to score a used alternator cheap , have it rebuilt and keep the crappy autozone unit as a back up since getting them takes a minimum of a day.

Reply to
simpleton

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