Battery Gettin Hot!

rbray · #1 (**permalink**) 05-09-2004, 03:03 PM

I had my car on a long drive today and I noticed that the amp meter was always on the postive side. I stopped and checked the battery and it was very hot to the touch. The rest of the way home I had the brights on and the amp gauge was reading zero.
The battery was still hot though.
This cant' be a good sign. What do I need to do to fix this?

Thanks

Ron61 · #2 (**permalink**) 05-09-2004, 04:14 PM

Rbray,

First off try to determine what the problem is. You could have a short somewhere that is drawing some current or your alternator could be putting out to much. Take a voltmeter and measure across the battery terminals with the car running and you should read around 13 - 15 volts. If more than this, you are getting to much from the alternator. With the car shut off, you can measure the voltage and it should be right at 12 volts. If you have a short that should make the voltage start to drop after the car sets for a while. The amp meter will normally go on the positive side if your battery is a little low as the alternator is charging it. If this just started and the battery is very hot, you could possibly have a bad plate in the battery. You can have the battery tested at most service stations and it just takes a moment to run a load test on it. Hope this gives you a starting place and some of the others will have more ideas too.

Ron

rbray · #3 (**permalink**) 05-09-2004, 04:19 PM

Ron,
thanks for the tips

Mr.Fixit · #4 (**permalink**) 05-10-2004, 06:54 AM

Guessing bad voltage regulator, causing alternator to put out max amps always, and it only evened out with demand when brights were on.

rbray · #5 (**permalink**) 05-10-2004, 06:59 AM

Voltage regulator? Ok, I'm an idiot, but I don't have one of those installed. From your comments I'm guessing that I need one.
What kind should I get and where in the electrical system does it tie into?
Thanks for helping a wanna be car guy

trularin · #6 (**permalink**) 05-10-2004, 08:25 AM

rbray, you may have what they call a "single wire setup."

Here is a good test.

Start the car.
remove the positive cable from the battery. Is the car still running? No, bad regulator or alternator. Yes, go on.
Take a voltmeter and read the voltage across the positive cable ( NOT connected to the battery ) and ground. Is it above 15 V, your regulator may be at max and need to be replaced. Less than 13.8V and I wouls say the regulator is set too low and needs to be replaced.

With the engine running, voltmeter connected, turn on the lights. Did the engine RPMs drop a little? Did the voltage reading drop a little? It should. If it was above 15 V and turning on the lights drops it down to 13.8 to 14.2V, Mr.fixit is correct.

Just a thought.

Cobra20646 · #7 (**permalink**) 05-11-2004, 08:05 AM

Have to agree with Fixit.... sounds like the regulator is not cutting the voltage back and over chargine the battery.

Two type of alternators..... one with external regulator and one with the regulator as part of the alternator. And two types of internal units.... one that requires a "field" voltage to be applied (usually by the ignition switch) to start the alternator working (has two or three wires), and the "one" wire that does all this work via one wire.

Most auto parts houses have a test fixture to test alternators. Get it done first. And you could have cooked the electrolyte out of the battery as a result of it getting really hot, so you may be in the market for a new battery too.

Rich · #8 (**permalink**) 05-11-2004, 09:45 AM

I would get this fixed ASAP. I had a battery explode in a '73 911 due to an overcharging alternator...it was not something I would ever like to experience again.

Fortunately, when it blew, I was on my way to trade the car in and the dealer said, "No problem, we'll just hose it out". Even more fortunately, '73 911's have two small 12 volt batteries and I was able to make it on one battery. I spoke to the current owner of the car a couple weeks ago and he said he can still smell battery acid (5 years later).

rbray · #9 (**permalink**) 05-11-2004, 10:10 AM

thanks for all the advice guys.
I talked to Bob at EM and the sent me the part number for the voltage regulator and a wiring diagram to install the unit.
I will let you know how I make out.

HighPlainsDrifter · #10 (**permalink**) 05-11-2004, 11:15 AM

Hi,
Running an ammeter is dangerous if it's not hooked up correctly.It must be in series with the main battery supply.It also must have a #8 [#10 will do] gauge wire to the battery and then fuse block.

You should check and see that ALL power goes through the ammeter. [Disconnect it and see if any other circuits work]

If it's wired in parrallel to the battery , it will act as a shunt and backfeed current to the battery.

Good luck,
Perry.

Cobra20646 · #11 (**permalink**) 05-11-2004, 12:43 PM

Perry,

What you say is correct... except... don't include the starter motor in the ammeter circuit. It is not designed to carry that amount of current and will cause it to fail.... immediately :-(

Michael C Henry · #12 (**permalink**) 05-16-2004, 05:33 PM

In 72 when I drove My AC from LA to Iowa the voltage reg let the alt go niuts and it cooked the battery going into Denver.Had to hold up that night.Burnt a dandy hole in the car cover laying on the battery in the trunk.Battery was all swollen fron that point on .The battery gave up that fall.

rbray · #13 (**permalink**) 05-16-2004, 05:44 PM

thanks for all the advice guys.
We tried to install a voltage regulator and in the process I'm think we fried the MSD in the process.
Oh well. I'll have the guys at E-M check in to it while they are painting the car.
Thanks