Thankfully, now that I got the radio working and in a programmable state, I no longer have to worry about that.
I did have an issue with one of the Impres batteries. When I went to charge it with my Impres charger, the LED on the charger went to yellow, indicating that there was some sort of issue with the battery. The battery was working fine, and I only dropped it in after the radio gave me a low battery message. Is there any particular reason why a perfectly good battery might be doing this? Just so you know, the same charger charges the other two Impres batteries fine, so I don't think the charger is the issue.
When the LED is yellow, the Impress charger is DISCHARGING the battery. After the discharge is complete, the LED will turn red. To bypass the discharge cycle, put the battery in the charger. If it turns yellow, remove the battery for three seconds then put it back in. The LED should change to RED, indicating it is charging. When it is at 90% charge, it will flash green. Solid green means it is done.