FDK (formerly Sanyo) Twicell (formerly Eneloop) 4.8V, 2000mAh, AA 4 Cell Square Pack.FDK's new more environmentally friendly NiMH battery. Although these are advertised as charged and ready to go right out of the package, we recommend a forming charge period prior to use. The Twicell NiMH type has lower daily self discharge than typical NiMH cells. These cells have done well in our in house tests and I feel good about offering them for RC usage.
Be aware this cell is a newer product and does not have a deep record in the RC community. However, thus far they seem to be performing well. We offer them for your evaluation.
Overnight charging suggestion is stock factory wall wart 50mah or less.
Although FDK's website shows Cx1 (capacity x 1) fast charge rates with a NiMH rated charger, I'm not prepared to warranty any packs damaged by fast charging or peak charging in any form. If you insist on experimenting with fast charging and damage a pack, call FDK, not Radical RC.
FDK HR-3UTG Twicell Battery - 1.2 Volt 1900mAh AA Ni-MH Button Top ( extending ) Weight 51.5g, 1.8 oz.
 "FDK/Sanyo Twicell 2000mah NiMH AA 4-Cell 4.8V Square Pack")