Everyone Looking for those solar chargers for walkie talkies that were distributed years ago

[CheyenneWills]

For any emergency related devices, a good idea is to keep an unopened pack of batteries near the device.

Also different types of batteries have different discharge rates.  For example alkaline batteries will gradually lose voltage over a long period, while lithium batteries will hold their voltage for a long time then just "quit".  Rechargeables typically don't last as long as non-rechargeable and some rechargables will slowly fail to recharge or hold a charge after a period of time