Rick
I use AA batteries from
www.batteryspace.com. 5 cells for the reciever and 8 cells for the transmitter. They have AA batteries (2200 ma NiMh) with soldering tabs, that make putting packs together easy. If you still have your Apak battery charger, you can still continue using it by adding a Thermistor and using a 3 wire lead as before. I have made several packs for the guys here in Jacksonville that used Apak charger and wanted to continue to use their Apak chargers. They sell the battery either single cell or you can get 20 cells for about $25.00.
You can get the Thermsitor from
www.jameco.com. The Jameco part number: 207037 and the NTC part number: NTC-103. The Thermistor runs about 39 - 59 cents. If you want to go this root, let me know and I will tell how to install the thermistor. (Very easy)
You can also get smart chargers from
www.batteryspace.com that also work well without thermistors. I've been useing them for over 2 years without any trouble.. They run about $27.00 for 6V charger and $29.00 for the 12V charger.