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Battery Heater

Posted on Sat 14 October 2023

Battery Heater Test Setup

As the fall sets in and the winter is coming, I did some test of a battery heater system. The parts of this system are:

The DROK temperature control board is a nice little board with a temperature sensor that can be used to control the output. The temperature sensor is a thermistor that is attached to the board with a 2 pin connector. The board has a 3 pin connector for the output. The output can be configured to be on when the temperature is above or below the set point. The board only supports Celsius display and settings.

The heaters are 12V 15W silicone pads. They are 50mm x 100mm.

At 24.8 Volts

With the heating pads off the DROK draws 0.001A. The heating pads draw 1.377. The pads reach over 300F!!

At that temperature they are hot enoogh to melt XPS foam very quickly. They did not seem to have any effect on the Coosa board.

NOTE: I am considering these materials in my winter battery enclosure.

Comparisons at other voltages:

Volts DC DROK Only (A) Pads On (A) Pads Temp. (F)
24.8 0.001 1.377 300 (open air)
13.8 0.004 0.773 190 (covered 5 min)
12.0 0.006 0.690 220 (covered 25 min)

The 12V test was done with the pads covered with a piece of XPS foam for over 15 minutes. I was reading 200F max, but usually around 190F. At 25 minutes, I did checked again and it was 220 and had started to melt the XPS. I uncovered the pads and they cooled down to 190F rapidly. The room I was in was 71.2F.

I then set some 1 inch wide by 1/8" thick aluminum bar on the plates and let is sit for 10 minutes. The temperature of the bars was max 93F and as low as 77F in the end not under the pads.

Next test was to use the aluminum bar and set the XPS directly on the bars. 10 minutes in max temp was 122F and the pads were around 135F. The XPS was not melting.

I'm not decided exactly how I will go but I thought this was interesting and worth sharing. Some thoughts:

  • Definitely do not want to put the XPS directly on the pads. I'd even say not on the aluminum bars or other heat sink either to be safe.
  • Definitely want to run at lower voltage. I did test at 5V and the pads did not get warm at all so 12V it is.
  • A heatsink greatly reduces the max temperature of the pads even when covered with the XPS there was enough air movement to keep the pads from getting too hot and melting the XPS.