[hrbuckley]

Leaving a lithium battery uncharged for a long period of time is one of the ways to ruin it. Common advice if you aren't going to be using a lithium battery for a long period is to fully charge it, run it down to 50% then remove it for storage. The PB battery can't be (easily) removed so you do need to periodically check the device to see where the battery charge is. Failing to do that can result in a battery that won't take or hold a charge.