Fox offers two versions of the EP battery series: a standard model and a variant with an integrated warm-up function to help counteract the effects of very low temperatures.
If you have a standard battery and wish to connect a heated version in parallel, they will work together. However, the warm-up function on the heated battery will not activate. Instead, both batteries will operate in the same way as standard models connected in parallel.
For batteries to function effectively in parallel, they should not be operating at significantly different temperatures. Any reduction in charge current due to a drop in temperature is based on the lowest recorded cell temperature among all connected batteries. Since batteries in parallel charge and discharge at the same rate, activating the warm-up function on just one battery would provide no real benefit—the charge rate would still adjust according to the coldest cell temperature across all units, nullifying any advantage the warm-up function might offer.
