My battery is overheated

I would say its more likely you have an electrical problem - maybe the voltage reg is not working & so the battery is over charging.

Suggest you get it looked at and don't drive it till you have because next step is a battery melt down & possible fire - I know someone who lost a Mondial like that.

 

I'd say "overcharging" too.....you could insulate the piping but the battery is behind the radiator in all of our cars, not the best place, but there it is!!

 

I was just in the same spot. You might top up the battery if it needs it or if you can and check out your head light brightness when you rev the engine to about 3000. If the lights get really bright then I would replace the Voltage regulator on the back of the alternator. Normal voltage in the system should be around 13.5 to 14.4 volts running and about 12.5 volts with the engine not running. The alternator is capable of producing a lot of voltage unregulated which can fry things! You can check the value just about anyplace with a hot wire, like the emergency lamp socket. Connect the hot + to a meter the - on the meter to ground or with a VOM. Bosch VR is about $35-$40 from Bosch, World parts has them. Quick and pretty easy job. Much cheaper than new head lamps or a battery.

 

I wouldn't drive it till you do and when you fix it I would be inclined to replace the battery because you can't be certain what damage has been done to it.

Cost of replacement battery vs cost of replacement car = "no-brainer"!

 

I think you got the right answers -- especially checking voltage at the battery at 3000rpm. If >15 then the alternator is putting out too much. I guess the regulator is built into the alternator?

As for the heat part it is probably not a big deal. On my Harley the battery is surrounded horse shoe style by the oil tank -- perfectly ideal if you want to ensure the battery gets a lot of heat. In the "old" days I used to have to replace the battery every year. Now with the new sealed gel batteries they last 2-3 years at least even in these extreme conditions.

 

The VR is in behind the heat shield on the back of the alternator it also is the brush holder for the rotor so it has to graphite brushes on springs. Looks like this:
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Not positive but it shouldnt matter. As long as the comutator dia is right. I found that a BMW 5 series is the same part. The differiance might be in the voltage out put 14.1 or 14.4 All the Bosch VR's I have seen have the number on the case yours might be an after market part.