What is battery temperature compensation?

Many charger manufacturers have taken note of the increased demand on a battery to charge in cold weather conditions but high temps are just as important to note. While the voltage variants may differ from one battery manufacture to another a general rule of +/- 0.03 volts per degree C above or below 250C per cell.

This feature requires a temperature sensor to be located near the batteries and or on the batteries. Which is best? Well if it's cold conditions you face often then between a pack of 2 or more batteries is ideal because the batteries will be cold in the middle. You could just as easily argue that if the cabinet is cold and the batteries were being used that they would still be warm internally which we'd have to agree with also.
You could also state that in high-temperature conditions the compartment would be hotter than the batteries so reducing the battery voltage prior to thermal runaway would be advantageous. Just as if you are monitoring the temperature of the batteries directly if there was a dead cell the battery would be hot and potentially gassing (which is bad). So early indication of this is best. But we'd add that a warm gassing battery would also heat up a battery compartment so the ambient temp would increase anyway.

In general, the thing this is really important is the upper and lower temperatures. Below Zero you shouldn't be charging and above 400C you shouldn't be charging what happens in the middle is your applications use are an ongoing variable that either extends or reduces battery longevity.

It's important to note though that Temperature Compensation is the ability to automatically alter the charging voltage due to the environmental temperature the batteries are stored/housed in and not anything to do with charger temps, this is typically understood when an external temperature sensor is available and or provided.