Smoky battery is never good.

December 17, 2007 5:16 PM

Why did my battery start to smoke in my lovely (but old) car?

OK metafilter hive mind, do me this solid and tell me if any of you have run into this problem.

My poor little slant six 66 Dart would not start when I got into the car. I pulled the alternator, got it tested and it was bad. Good for me, an easy fix. So, I pulled my battery, charged it overnight on a battery charger, tossed it in my car this morning and started her up. She wouldn't turn over but that doesn't really mean much because she never turns over first try. The car was strong, it was getting power, all was fine.

Tried to start it again and nothing happened. It was so quiet I could hear crickets in the background. Suddenly my battery starts to smoke. Very scary.

I think it may be a voltage regulator issue but it was replaced about a year ago and so perhaps not. My alternator is hooked up right but I don't think that's the problem.

Question is, could a bad battery be at fault and nothing more? I doubt it but perhaps. OR, could it be the fault of a voltage regulator. I have had problems with that in the past but it melted wires not killed my battery in one smoky blow.

Oh and before you ask, "did you hook your battery up right?" the answer is yes, yes, yes. It's been taken out of my car more times than Bush has told a lie and I know which way it needs to go.

You guys are smart smart smart so I know you'll have more insight than I.

posted by Holy foxy moxie batman! to travel & transportation (10 comments total)

Batteries smoke because of very high rates of discharge, usually. Possible causes are:

1: Battery is not installed correctly (you say this is discounted).

2: Alternator incorrectly installed and so earthing live feed from battery.

3: It sounds like the alternator wasn't installed when you ran it up - was the feed from/to the alternator isolated correctly? If this was earthed in some way, the battery will short to ground through this route.

4: Battery died during charging - unlikely if the car started. It MAY have given up it's last ghost during starting, but they usually just go flat, rather than smoke. Total internal plate failure is a possibility, though, albeit slim. Does the battery hold charge if it is off the car? If so, wire it back up and stick a voltmeter across it.

5: Starter motor failure (internal) causing the feed to short out. (long shot)

6: Some other random spanner/wrench/screwdriver on the wires somewhere from an utterly unrelated other time. Have you lost the wrench you used to put the battery back in with...? ;)

7: The alternator took the voltage regulator down when it died and it is shorted/melted inside.


(I'm still thinking about this, but that gives you something to go on and eliminate).
posted by Brockles at 5:28 PM on December 17, 2007

tossed it in my car this morning and started her up. She wouldn't turn over but that doesn't really mean much because she never turns over first try. The car was strong, it was getting power, all was fine.

Actually, can you clarify some things for me, as your terminology is confusing.

"Turning over" is when the engine is spinning on the starter motor.

"Starting" is the point when you release the key because the engine is running.

From your post, it sounds like the engine didn't turn over, but just sat there and smoked when you put the key to 'start'. I am assuming that "It was getting power, all was fine" means the ignition lights were on, rather than the engine was running. I cant tell for sure if it started at all, then died, or whether the engine never actually rotated on electrical power. Was there any clicking? Any sign of life at all?

So, if my interpretation (that it never actually started) is correct, you need to try again (if you can, but not with a new battery!) and see if the battery smokes with just the ignition on, or if it is when you engage the starter motor. Beforehand, check all wiring - alternator, starter, the works and check for shorts, burnt insulation and any sign of 'other than battery' heat. Then I'd isolate the starter (as a first point) by disconnecting it (isolate the wires properly) and then turn the ignition on. Keep a close, close eye on the battery and wires. See if anything gets hot. The second it does, turn it off. If it doesn't, I'd have your starter tested.

This is the cheapest way to test it - trial and error. If you have a new alternator and they haven't sold you the wrong one (ie wrong wiring) and this is ALL you have changed since the last time you started and ran the car, it sounds like the Voltage reg, the wiring or the battery itself are at fault. The starter is another possibility, and is easy to check at an automotive store if you need to discount it as being an issue before you start replacing stuff. I have known a starter crap itself internally like this on an old car. Never discount coincidence on the more senior automobiles.
posted by Brockles at 5:39 PM on December 17, 2007

Good ideas! Let's see,

1: Battery is not installed correctly; sure it is and triple checked it just to be triple sure. :)

2: Alternator incorrectly installed and so earthing live feed from battery.

Only two wires to my alternator. One fld and the battery. I know it's odd that it only takes one fld but that is the way my dart is, was and always will be.

4: . Does the battery hold charge if it is off the car? If so, wire it back up and stick a voltmeter across it.

I could do that but I'm fairly certain that 1. I don't want to wire that puppy back up and 2. It's toasted and well fried. It really really smoked. A lot.

5: Starter motor failure (internal) causing the feed to short out. (long shot)

Just put in a new starter last month.

6: Some other random spanner/wrench/screwdriver on the wires somewhere from an utterly unrelated other time. Have you lost the wrench you used to put the battery back in with...? ;)

There is a loose wire coming off my voltage regulator but it's always been a little loose. Possible though.


7: The alternator took the voltage regulator down when it died and it is shorted/melted inside.

That may be likely. I will say that my lights have been dimming over the course of the last month so it may have been a slow death. Can a voltage regulator take out an alternator? I put in an alternator last year.
posted by Holy foxy moxie batman! at 5:39 PM on December 17, 2007

Yes, A VR can wipe out an alternator. Mine did just this summer (1991 Ford Crown Vic). They both fried. The alternator was charging/running at 17 volts and killed the control side of the Alternator.

Something caused a very fast discharge of that battery (especially as it is "well fried"!). It sounds like you have (with the new components) discounted much of it.

If the VR is cheap, I'd replace it on the dimming lights evidence alone. A bad VR can fry all sorts of stuff (mine took out the sprark module, too) and it'd be high on my precaution changing list (pending cost/availability. I'd certainly fix any loose wire I found, as well. That may, on its own, be why the voltage regulator isn't functioning correctly.

If you have checked all the big fat battery wires, then I think you are good. The only wires that can flow enough current to toast the battery before frying the wiring loom are the big fat fellas. If it was anything else, the wires would have gone first. Is there no other loom damage?

I'd go with new VR, new battery, final paranoia wiring check and have someone else turn the key while I watched closely under the bonnet...
posted by Brockles at 5:59 PM on December 17, 2007

There seems to be no damage in my wires. It was just a smoking battery and that was it. Whatever took out my battery did so quite well because there was no power to anything at all. Thanks for your advice. It's about what I was thinking of doing too I just want to kind of pick some brains because I really don't want to hook up a new battery only to have it smoke.
posted by Holy foxy moxie batman! at 6:03 PM on December 17, 2007

It really sounds to me like a dead short. In other words, if there was no 'chunk' sound when you first turned the key (the sound of the solenoid on the starter), then I think the wiring was somehow arranged so that the battery was wired to itself without going through any significant resistance.

I believe (note the weakness of this term relative to 'I think' and 'I'm sure') that it is possible having the wrong alternator could result in a path directly to ground in some cases. This is such an old car, I can hardly believe you got a direct replacement alternator-- it's probably a substitute someone said would work.

Try putting your old alternator back in, if you still have it, and see if you can get the engine running that way. A car will run for a long time with a completely dead alternator, if the battery starts out charged and functional. If it runs, get another new alternator, and make absolutely sure it is compatible with your car.
posted by jamjam at 6:50 PM on December 17, 2007

The new alternator was tested before it was put in my car because I sometimes get bad right out of the box alternators. I don't have my old alternator and it's a moot point now because my battery is toasted. I like where your going with this though and it's a good thought but I have had to deal with three alternators in my car (long story) and I'm fairly certain that it's the right one.
posted by Holy foxy moxie batman! at 7:10 PM on December 17, 2007

The new alternator was tested before it was put in my car because I sometimes get bad right out of the box alternators.

The incorrect wiring (as in its compatibility with the car) could still be in the alternator: Just because the alternator works as designed, doesn't mean it is right for your car necessarily - alternator testing is not done 'context dependent' but only to the spec of the alternator. If the alternator is the wrong type, it'd cause issues.. Is your car negative earth, for example? If it isn't (I seem to think that the 60's were around the time these things changed) then that would certainly explain it. But again, you can just disconnect the alternator in most cases and see if it will start. It only needs it to charge the battery anyway, in an old car.

I'd check your wiring diagram, though.
posted by Brockles at 9:13 PM on December 17, 2007

Maybe this is a long shot, but on my dad's old car we had to phase in a new alternator, or it didn't work right. Not sure what that even means.

Actually, come to think of it, it probably just means to check that it isn't a positive earth Alternator.


A '66 came with an alternator stock? Seems like it would have had a generator with a VR. I would dub this a "probably should work" replacement.
posted by rocket_johnny at 4:34 AM on December 18, 2007

Sounds to me like you had a dead short internal to the battery. Easily caused by moving it around or connecting/disconnecting the terminals. The fact that your wires are OK but the battery is toasty is the indicator.

rocket_johnny writes "'66 came with an alternator stock? Seems like it would have had a generator with a VR. I would dub this a "probably should work" replacement."

Alternators were standard equipment on all Chryslers starting in 1960. I don't think the /6 (first used in 59) ever had a generator.

rocket_johnny writes "Maybe this is a long shot, but on my dad's old car we had to phase in a new alternator, or it didn't work right. Not sure what that even means."

Not required on Chryslers of this vintage, it's mostly a GM thing.

The first thing to check on a no start valiant is the ballast resistor. Just go buy a new one and swap it out. It's the white ceramic thing on the firewall usually between the hinge and the brake booster. If it fixes the problem go buy a second one for a spare. If not you already had a spare that you should carry with you always.
Problems with the wire feeding the gauge is extremely common. Check the firewall connection and the terminals on the back of the gauge. Also the start solenoid is external. You should double check it isn't shorting out to ground.

You say the voltage regulator was replaced. Make sure the firewall holes where it's mounted are shiny. It's classic for a new regulator not to work because of rust in that area. You might also want to consider changing the electronic ignition box if it's original.Or at least unmount it from the firewall and shine up the connection.

allpar.com has tons of troubleshooting tips for vintage Chryslers including no-start condition on carbed engines..
posted by Mitheral at 1:05 PM on December 18, 2007