Resonators lose 15% of their total XM capacity per day, even without enemy attacks. This decay means that a portal left unattended for seven days will revert back to unclaimed status. Recharging is the act of transferring some of the XM from your scanner‘s reserves into a friendly portal’s resonators in order to replenish XM lost to decay or enemy attacks.
How to Recharge Resonators
To recharge a portal’s resonators, the portal must belong to your faction, and you must either be standing within action range of it (40 meters) or hold that portal’s key. Select the portal from the scanner screen or select its key from your inventory, then tap the “Recharge” button to bring up the recharge screen. The meter inside each hex shows the level of charge for the corresponding resonator. A resonator that is not fully charged will have a charge meter filled with a gradient; a fully charged resonator’s bar meter will be solid green or blue.
Each recharge consumes up to 1,000 XM. Tap the “Recharge All” button to distribute it evenly between all the portal’s resonators that are not fully charged. Tapping a hex for a specific resonator changes the button to read “Recharge;” the entire 1,000 XM will then be directed only to that resonator. Tap the selected hex or the center to deselect a resonator. When the targeted resonator(s) are fully charged, the button will dim. Any unused XM is returned to your reserves. Note that the higher a resonator’s level, the greater its XM capacity, and thus it will require more charges to fill.
Long-pressing the “Recharge All” or “Recharge” button will perform a “quick recharge.” This will draw up to 15,000 XM from your reserves (in blocks of 1,000 XM) at once for recharging, distributing it in the same fashion as a regular recharge. This is handy if you need to quickly shore up a portal that is under attack. As with the “slow recharge” method, any unused XM is returned to your reserves.
You get 10 AP per recharge, regardless of how much XM is transferred by the action.
When you are within the portal’s action range, recharges are always 100% efficient: all the XM you spend is transferred to the portal’s resonators. Remote recharges, however, lose some XM in the transfer, and recharge efficiency decreases with range. If the efficiency drops below 50%, you will not be able to recharge the portal. However, your remote recharges will become more efficient as you level up. Your maximum remote recharge range (the distance at which recharge efficiency hits 50%) is computed as follows:
d = 250 × L
…where d is the distance in kilometers and L is your current agent level. The remote recharge efficiency at a particular distance is computed as follows:
E = 100 – 0.2d ÷ L
…where E is the remote recharge efficiency percentage. Remember that when E goes below 50%, you cannot recharge. So for example, if you are a level 4 agent and have a guardian portal 100 kilometers away, you can recharge it at 95% efficiency. This means that with each 1,000 XM recharge, the portal receives 950 XM, while 50 XM is wasted.
The best recharging strategy depends on the circumstances:
- Defending a portal: Use the quick “Recharge All” feature. If you are outgunned, quick recharge the highest level resonators, or ones that are not accessible to attackers (inside a building, over water, etc.). Note that this will significantly deplete your reserves, meaning that you are likely to need to use a power cube sooner to continue the fight. However, the quicker recharging means you will have more time to do so.
- Maximizing AP gain: Use the slow “Recharge All” feature, stopping just short of topping off any one resonator. Use a single recharge on that one resonator so that it is fully recharged. Repeat until all resonators are recharged.
- Earning the Recharger medal: All methods work equally well for this purpose, since the medal only cares about the amount of XM transferred to resonators.
If the resonator meters fail to increase when you recharge, you may have run afoul of speedlock. Stop moving, wait a bit and try again.
Because it costs so much XM, you might want to hold off recharging if there isn’t any readily available XM where you are and you aren’t willing to use power cubes.
If you’re playing alone, and you have no particular task you need to perform when there’s plenty of XM around to replenish your reserves, you should look through the keys in your inventory and see if any friendly portals need recharging. Any XM you don’t pick up because your reserves are full (and that you aren’t intentionally leaving behind for other agents) is wasted potential. Recharge some portals and pick up that XM.