Re: battery temperature sensor

From: Eric (huffy340@gmail.com)
Date: Sat Oct 23 2010 - 12:34:05 EDT


> The battery temperature sensor is also used to determine if
> certain OBDII tests should be run, like the O2 sensor heater
> tests, leak detection pump, etc. If the battery temp sensor
> reads below 20 degrees F, these tests are disabled.

> ... [and] as an input to the transmission control module (on trucks equipped with an

Why do they use the battery temperature for those?

I thought we had air temp sensors on these, which would seem to be
more related given that batteries get warm when charging.

> If you are concerned about it and want the most accurate readings
> possible, as long as the sensor is touching the bottom of the
> battery, the readings should be just as accurate as stock.

> However, even if the bottom of the battery has a weird shape and
> thus the temp sensor can't touch it, its still in the battery
> tray, so I don't think you'd get inaccuracy to the point where it
> would cause any problems. If anything, maybe your battery charge
> rate would be a little higher than might otherwise be.

I don't think the sensor in there now necessarily *touches* the
battery very well anyway, so that should be OK. I'll look when i
make it outside (i thought it was recessed a little).

I was thinking more along the lines that the low internal
resistance of the optima would result in a lower temperature for
the same charge rate, possibly confusing the PCM.

If the battery box still fits, that will also help keep the sensor
in air that is the same temperature as the battery.

Thanks for the feedback, folks. Sounds good and i'll switch when
the time comes. Atm, i just need to replace the battery
cable connector. I think the battery is still OK, but wanted to be
prepared.



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