Monday, January 24, 2011

Battery Warmers

With the drivetrain vibration fixed (sort of), the next problem is that the batteries have been so cold that they just won't give me enough juice.  Using a surface thermometer, I measured the temperature at 33 degrees F.  Brr.

I ordered battery warmers from KTA Services, one for each battery.  Farnam Battery Heater Pads, thin mica sheets sandwiching a ribbon heater.  They run on 120V AC, so I wired them so that they will be powered only when the car is charging.  For once, I actually successfully planned ahead when I brought a neutral line into the car in addition to the two hot wires and ground.  In case anyone's interested, here's the wiring diagram for the heaters.  As you can see, I split the power for the heater between the two hot leads of the 220V AC coming into the car.
The worst part about installing the heaters is that the batteries have to come out.  Ugh.  Heavy.  Here are the batteries from the rear box in all their weighty glory.
Here are the heaters laid out in the bottom of the rear battery box.
And with the batteries in place.
In this view you can see the the wiring for the heaters.  I ran the wires along the sides of the box so the batteries can come out without affecting the heater wiring.  And here the batteries are back in place.  Finally.
Here's the control box wiring.
And the box in place in the trunk of the car.
Notice the temperature of the batteries?  The controller on the left is for the rear box, the one on the right for the radiator box.  The outside temperature was about 15 degrees F at the time.  Nice.

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