Where did you purchase your battery mat?
JC Whitney
2 x sku 54ZX1179W 36"L 80-Watts Blanket-type Battery Warmer $29.99/ea
2 x sku 54ZX1427R 28"L 50-Watts Blanket-type Battery Warmer $29.99/ea
i have 4 battery boxes, 2 with 6 batts (3x2) and 2 with 4 (4x1).
i used the 80 watt units under the 6 batteries (took apart blanket and wrapped it into a 3x2 configuration)
and the 50 watt units under the 4 batteries (all in row = MUCH easier).
This gave approximately the same amount of wattage per battery through-out
80 / 6 = 13.33/watts/battery in the 3x2's and 50/4 = 12.5 watts/battery in the 4x1's
equal insulation and wattage in gives very similar temps
Will a waterbed heater work?
i thought about that, but they typically are very large, very high powered and expensive! Rick Lane from Canada suggested the battery warming blankets laid flat.
How thick should the foam insulation be?
Rick suggested 3/4" min so that is what i used. Other's have used 1/2" due to space limitations. Anything is better than nothing. The insulation is on all 6 sides with a plexiglass cover for the winter. in the summer months, i remove the top insulation panel and the plexi lid.
What is the optimum temperature?
Batteries are rated at 72 degrees typically. Higher temps will give better range with shorter battery life. People in AZ have to cool their batteries in the summer months! Anything above ambient is good... 60 is better than 50 is better than 40... when getting below freezing, range will got to 50% or less very quickly! The temp has to be raised higher for both the charge and discharge cycles.
What is the max differential between battery temps to avoid unequal charging?
The closer the better. i'm guessing 5-10 degrees isn't a biggie, but if you heat one box and not another on a regular basis, that pack will get uneven and likely die a premature death.
