somewhat offtopic, Absorbed glass mat auto battery question

i have a small AGM battery installed under the hood of a turbo engine (14 inches from the engine, 24inches from the turbo). i installed some foil bubble wrap around the battery as a heat shield. is this helpful in shielding heat or hurt-full in trapping heat. i assumed that it would be helpful in a high temp turbo application to avoid early deterioration. I've even considered only putting shielding on the side closest to the turbo to shield but not trap heat.

the answer i got from the manufacturer wasn't convincing. "common sense tells us to put the foil heat protector
on the side of the battery closest to the heat source
and leave the other side open."

i wasn't looking for a "common sense" answer. perhaps something more technical in nature.


final question...do AGM batteries even care much about temps?

My VW GTI (1.8 turbo engine) had an insulating wrap all the way around the battery. Actually, everything had insulating wrap in the engine bay, most of it looked like some type of woven fiberglass mat with foil on one side. The battery just had a thick "blanket" around it. I only had the car three years, and it still had the original battery when I sold it.

Can't tell you how heat-sensitive an AGM battery is specifically, but I'd never think it was a bad idea to wrap one!

Hello Nmanchin,

Heat kills batteries. Do whatever you can to minimize the heat on the battery.

The battery will not produce a lot of heat in normal use, so you can either wrap it or shield it. Wrapping it may keep the battery cooler in an engine compartment.

My son's BMW has the battery in the trunk. Problem solved...

Tom

thanks folks! i'll keep it fully wrapped!

yep, it's on a TT, similar set up as the golf (1.8t). my original too had a fiber wrap.

nmanchin said:

the answer i got from the manufacturer wasn't convincing. "common sense tells us to put the foil heat protector
on the side of the battery closest to the heat source
and leave the other side open."

Click to expand...

If I were doing nothing else besides shielding, that would be my approach also.

By shielding the "hot side", you keep most of the radiant heat from the turbo from entering the battery and the battery will eventually reach the ambient temperature of the engine compartment. Any radiant heat from the turbo that makes it through the shield into the battery has a path to escape from the 5 other sides. If you fully wrap the battery, it will STILL heat up, although more slowly. But given enough time it will actually get HOTTER than the partially-shielded battery. Because, some of the radiant heat from the turbo will get into the battery, but is then held in by the total insulation wrap. Also, when shut down the insulation will hold the heat in the battery for a long time.

The best approach would be to construct a "battery box" to enclose the battery, with sufficient airspace surrounding the battery. This in conjunction with a duct which allows cool outside air to flow into the box, and carry heat out. The insulation shielding would then be applied to the heat-facing side of the box, not the battery.

This should help illustrate:

http://www.finishlineperformance.com/rx8/docs/pdf/01-042-04-1429.pdf


To answer your second questioni - AGM batteries are still lead/acid and will benefit from heat management.