Cameron Motor Works Electric Vehicle Conversion

Battery Heating

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The Batteries


January 2005


Batteries operate best at a specific temperature. For lead acid batteries this is 25oC.

Points to Consider

  • Battery heaters are rarely run off the pack, they are plugged into the main AC outlet while the car is charging, or before leaving on a trip.
  • Using a temperature control, the heaters can be left plugged in without having to worry about waste consumption.
  • Batteries heaters need to be temperature controlled



For the New Beetle Project, a series of Battery Blankets from Canadian Tire will be used to line the insulated battery boxes. These units are approx 50 watts each and run from AC mains power. They will only be used when the car is connected to the mains power.

Canadian Tire has two units:

  1. 36" 80 watt 24.99 11-3116
  2. 28" 50 watt 23.99 11-3118


Several 50W battery heaters from Canadian Tire and JB Auto were purchased. Their outer vinyl case and inner insulation was removed, then they were installed in the bottom of the insulated battery boxes.

Three battery heaters glused to the based of the battery box:

A rugged, reinforced vinyl is glued overtop of the heaters. This is the same material as used in the stock battery warmers.

Heater Control

The heaters are powered by 120VAC during charging. A temperature control need to ensure each pack is a close to optimal temperatures as possible. Originally an NC 30oC bimetallic switch was used, but upon testing, it was discovered that its' close temperature was too low.

The intention is to build a small circuit with a relay which has precise measurement control.

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