We design and manufacture battery chargers. I have done extensive testing on Li-Ion and NiMH batteries and their charge capacities. I will give you a couple of tips:
1. Energizer rechargeable NiMH batteries - junk! don't waste your hard-earned money. Duracell are a little better. Good batteries are not cheap, cheap batteries are not good.
2. Cheap $20 chargers will almost never charge your batteries over 2000mAh capacity, even if they have 2500mAh batteries included in the package. We have tested most of the currently offered general retail chargers and this is the standard. It has to do with the charging ICs that they use to operate these circuits.
If you buy one of those low-dollar chargers (not bad by the way), just buy the 2000mAh batteries. WalMart has a good one that has Energizer's brand on it. Microprocessor controlled and all 4 slots charge independently. Thermal protection and overcharge protection are included.
3. Don't count on over 40-50 complete charge/discharge cycles with any of the AA NiMH batteries that you can buy at the grocery store or X-Mart.
4. Don't run them completely down, let them set and then charge them up the night before a hunt and expect them to hold a good charge. They need a couple of cycles to get the chemical reactions going. Try to get in the habit of charging them when you get through using them and then put them on the charger for an hour or two each month while you are not using them.
5. Occasionally you can find the Lithium batteries in bulk for a good price. These work well for the money and great to have as backups since they have long shelf lives. Energizer's lithium batteries are very good.
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Only two defining forces have ever offered to die for you,
Jesus Christ and the American GI.
One died for your soul, the other for your freedom.