hot battery in 69...

[Kenneth G.]

hello everyone,

first a little background on my problem. about 3 weeks ago my 69 350/350hp battery gauge was operating normaly as i drove. then one day (at least for the next two times i drove it)the battery guage needle "ping ponged" back and forth wildly while driving. then the third time i drove it, this problem seemed to have stopped as the guage needle operated normaly between 0 and +40 (the 69 battery guage has -40, 0 and +40 as the readings). what could be some reasons for this? today i went to a car show that ended up being about 110 miles roundtrip (fairly long trip for me) and i noticed the battery guage needle was "pegged" at +40 the entire time on the highway (most of the trip was on highway), while in brief stop and go traffic it went between 0 and +40. what should the guage normally be reading when you drive? needle at 0?

after getting back home i noticed an odd smell in the car and it seemed to be coming from the back compartment area of the car (a burning, rotten egg type smel). i checked the back area and the compartments in the 69 and opened up the battery compartment to check on the battery. first thing i noticed was that the battery was HOT, almost burning hot! below the battery, i thought the fiberglass of the battery compartment was melted as there liquid there, but i believe this liquid was coming from the battery itself. The battery is new, about 2 months old (Sears die hard gold). i promptly disconnected the battery and took it out of the car.

I am not the best when it comes to the electricals of a car and was hoping someone could point me in the right direction. what should the guage read under normal conditions? could the fact that the guage was constantly pegged at +40 mean that the battery was getting "overcharged" causing it to get hot? what would cause this? thanks for any help and sorry about length of the post....

btw, i won a second place trophy at the show

Kenny #31871 : 69 350/350 hp , 4 speed with a/c convert.,

[Kevin M.]

Re: hot battery in 69...

Ken,

Can't help you with the battery problem, but did you clean up the liquid? A water baking soda mix to neutralize the acid when you clean it up would be a good idea. Might be an old school method but that's how I do it.

Kevin

[Kenneth G.]

Re: hot battery in 69...

kevin,

i didnt put down any baking soda, i just wiped up the liquid pretty good. i know this is an area where many vettes have the fiberglass eaten away by battery acid. in fact my own car was a victime of "battery compartment cancer" before being restored. ill have to go back tomorrow and clean it more thoroughly and m put some baking soda down. everyone else think that will be enough to protect the fiberglass there?

[John Walker]

Re: hot battery in 69...

Kevin; I have had a simular problem before and after extensive trouble shooting it turned out to be a bad battery( plates shorted inside), odd it would happen to a new one but you never know these days. John

[Joe R.]

Re: hot battery in 69...

Kenny,

You probably have a bad voltage regulator. You can get it checked by your Sears battery dealer.

Regards,

JR

[Kenneth G.]

Re: hot battery in 69...

in 1969 wasnt the voltage reg located inside the alternator??

[Reba Whittington]

Re: hot battery in 69...

1969 was the first year of the SI series alternator which had an integeral regulator

[Jack H.]

Several alternatives...

First, the fact that the battery was warm and you saw acid spilled in the battery compartment tells you the charging system was doing its thing and really supplying charge to the battery.

Now, overcharging can happen for a couple of reasons. One: the battery REALLY is low on charge and the charging system is doing what it was designed to do. IF a given cell within the battery was shorting out (mfgr defect, random breakdown), then the overall battery voltage would fall in lock-step to the loss of this cell. That would make the charging system 'see' a bona fide low battery charge condition (below the nominal 12 VDC range) and trigger it to provide charging current to pump the battery back up to normal level. EXCEPT, with a shorted cell, there's NO WAY the battery will ever return to normal and it's a matter of time before what's left of the battery is charged into 'oblivion' as yours was...

The other alternative is there's a fault in the charging system (either internal to the alternator, or external in the wiring harness) whereby the charging systems 'sees' a low battery condition that isn't real. In this case, the system will do what it's designed to do...deliver gobs of charging current to pump the battery back up to nominal. But, if it's a matter of the battery actually being good and the charging system being defective, that'll never happen and the battery will wind up being overcharged and ruined.

If you're not experienced in this area, almost any local auto electric shop can wheel out their charging diagnostic cart, hook it up to your car and exercise the various components individually to fault isolate the source(s) of the problem. That's a 15-minute job and there's no longer any guess work as to who's the guilty party. Finding and fixing the exact source(s) of the problem may take more time and cost you more...

But, I'd suggest this is a situation for learning. There was a reason for why designers put those gauges in the car in the first place... Watch 'em and the next time something 'wierd' shows up, SHUT THE CAR DOWN and go find/fix the problem instead of ignore it and hope it'll go away!