Resonators are powered by XM. Resonators start with a full charge, but the XM store is consumed at a rate of approximately 15% per day. Attacks on Resonators by XMPs also reduce their XM charge. Resonators will self-destruct when the XM charge reaches 0. If all Resonators deployed on a Portal go to zero, the Portal will revert to Neutral status.
Resonators can be Recharged using the RECHARGE Resonators action:
1. Choose the Portal when it is in “action range”
2. Touch RECHARGE resonators