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Old 05-13-2010, 05:09 PM   #6 (permalink)
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If you talk strictly Pba batteries. As temperature increases so does capacity but longevity decreases. You should use temperature compensation in your charge voltage profile. This will prevent overcharging in the heat and undercharging in the cold. Over and undercharging are the leading cause of early lead acid battery failure.

Generally speaking if you find the temperature to be comfortable so will a Pba battery. Most ratings are from a temp in the mid 70's (F).

Keep your battery cool and it will last longer. Run it hot and it will shorten the life. If you need performance and not longevity you may enjoy having a hot pack but be sure to monitor the charge voltage and look for the weakest link.

My Solectria has a fairly good insulation around the battery compartments which is bonded and not easily removable. Summer heat build up can be considerable from both driving and charging. When ambient temps are in the 100's it becomes more and more difficult to get the pack back into at least the 80's. Thankfully we have some cool night. I run compartment blowers and reduce charge rate in the summer, charging at the coolest possible time if able. A moderate drive easily raises the temp 5-10 degrees and a recharge another 5-10.

If you can remove insulation easily on all the batteries so they are the same temp I would do so. Your right in that the ambient air wouldn't be able to raise a insulated compartment as quickly but usage will and they aren't going to cool down very fast so a potential death spiral begins if you drive it much.

Stay cool.
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