XT-60 Empty / Full / Storage Indicator Cap

After searching I couldn't find an XT-60 battery cap/plug that I liked. I wanted something that would indicate if the battery was full or empty AND if it was at storage charge level.

For those that don't know, you should not leave your Li-Po batteries at either empty or full for any prolonged period as it will cause them to swell and die prematurely. For that reason you should discharge a full battery to 'storage level' of 3.8V per cell (or charge an empty battery up to).

To use, simply pu