battery temp sensor

Should the battery temperature sensor get all screwy since I changed to an Optima battery (red)? Nothing seems wrong, but the voltage doesn't read as high as it did with the old battery. I know I need to replace my cables, but that's for another thread.

What the fawk is a battery teperature gauge???? :huh:

What year have you got? I am unaware of a batt. temp sensor on any XJ model year, but I am opening to learning something new.

The new ones (don't know what year it started but I'll guess 1996 with the debut of OBD-II) have a sensor in the battery tray to signal the computer when the battery is overheating. The old XJs have the voltage regulator built into the alternator. The new ones have the regulator integrated as an ECU (or PCM) function.

Eagle said:

The new ones (don't know what year it started but I'll guess 1996 with the debut of OBD-II) have a sensor in the battery tray to signal the computer when the battery is overheating. The old XJs have the voltage regulator built into the alternator. The new ones have the regulator integrated as an ECU (or PCM) function.

Click to expand...

Hmmmmm....I guess I will have to check my 2000. I know my 92 did not have it.

If you want to see a picture of one go to www.jeepsareus.com, they have them in there.

http://www.jeepsareus.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=JAU&Product_Code=LV2

Add one requirement to the battery relocation project.

Timber said:

Should the battery temperature sensor get all screwy since I changed to an Optima battery (red)? Nothing seems wrong, but the voltage doesn't read as high as it did with the old battery. I know I need to replace my cables, but that's for another thread.

Click to expand...

What voltage are you talking about?
If you are talking about the dash volt guage, the batt temp sensor would have no effect on that.

The only way to read batt temp and sensor voltage is through a scan tool.

Really a non- issue as I see it, as long as the guage is 'close', then good enough. a different [new] battery can have an effect on how the system reads, and how much it charges. there is most likely less of a load on the alternator so the guage doesn't read as high as it did before.

Timber said:

Should the battery temperature sensor get all screwy since I changed to an Optima battery (red)? Nothing seems wrong, but the voltage doesn't read as high as it did with the old battery. I know I need to replace my cables, but that's for another thread.

Click to expand...

I have had 2 Optima,s 1-blue,1- red never noticed any problems other than the blue didn,t fit the tray until it was modified.96 model year
Wayne

Digger87xj said:

What voltage are you talking about?
If you are talking about the dash volt guage, the batt temp sensor would have no effect on that.

The only way to read batt temp and sensor voltage is through a scan tool.

Really a non- issue as I see it, as long as the guage is 'close', then good enough. a different [new] battery can have an effect on how the system reads, and how much it charges. there is most likely less of a load on the alternator so the guage doesn't read as high as it did before.

Click to expand...

I guess that because I (think I) actually understand how the sensor works, I may be making this harder than it really is. I figured that since Optimas run cooler, partially due to the lack of pressurized gases (the gel is literally colder than pressurized gas) that this will affect the charging rate. The colder the sensor reads, the higher the alt. output and vice versa. I also realize that the "voltmeter" on the dash isn't reading either true battery voltage or true charging voltage. I just know that it isn't reading as high as it did 20 minutes before putting the Optima in. Just don't want any problems this winter when the temp. sensor actually makes a difference in the charging rate of the battery.