Hi there!
AA sized Nimh's of well known brands. Lately I have been using Sanyo, GP and some Panasonic.
I always use 4 cells.
I have tested other brands but with dissapointing results. Some China batteries can be really bad.
BUT I have purchased and tested the new Sanyo Eneloop batteries and they seem some better than all I have used before. They also keep the voltage from last charge better than others. Think you can buy them at Conrads... I have prepared 4 packs and all my Perfect's will be equipped with that (my SL I flew some days ago in -11 is equipped with that). I had to order the batteries from Denmark since I have not seem them in Norway but I think Graupner will start to sell them as their own. This is just rumours offcourse as I dont know for a fact. People also say that Varta is selling them as "ready to go". Dont know the chemistry of the cells.
You dont need to do exstensive large tests to find the best batteries.
Normally flying a sailplane you dont use more than 3-400mah capacity in an hour flying at the most. I usually charge after an hour flying and I always top of the batteries on the way to fly. But I like to be fairly confident in my batteries.. So the easiest test is the following:
Charge a receiver pack and put it in the freezer for an hour. Take it out and connect it to your charger on discharge 1A. After 10min you should hopefully still have 4,5V on the display of the charger.
To be really sure you should also check that your receiver and servos will work on 4,5V. Some sadly dont.
Copy the txt if you want too