Ares 12 (or LTE version) have an internal backup battery in case of primary power failure.
Starting with firmware version 1.3.7 we have improved battery lifetime by changing its charging behaviour. Now it doesn't hold on 100% anymore, but charging is started only if the battery is lower than 80%.
Depending on your configuration, this could mean that your Ares will charge over 80% once every few weeks and its perfectly normal.
