The batteries in the Eon are replaceable. If you feel like your headphones’ battery life has declined, you can purchase new batteries from here.
Compatible batteries with the following specifications may also be used: 3.7V Lithium Ion 10440 Rechargeable Battery, Capacity 350mAh.
If you use a third-party battery, you need to do a little processing before it can be used.
To replace the battery, take off the cover as depicted in the diagram above. Remove the battery and place the new battery in the slot, taking care to align the pins correctly. Replace the cover, then repeat these steps for the other side.