Lets the charger adjust its voltage to the battery's actual temperature instead of assuming. On lead-acid this is the difference between a bank that lasts and one that cooks; on lithium it matters for low-temperature charge cutoff, which is the thing that quietly kills lithium banks in winter.

Cheap, and skipped far too often. If you own a MultiPlus, you want this on the battery.

Specifications
For MultiPlus, Quattro and GX devices
Manufacturer part number: ASS000001000