Sem Svizec , August 12, 2014; 09:04 A.M.
All these speedlights are powered by AA cells, preferably the NiMH type, either the high-capacity self-draining ones or the longer-holding Eneloop or similar. There is the question why flashes haven't moved to Li-ion like cameras.
The running assertion was that Li-ions in the same volume were not good at pulling out juice fast enough for quick recycling; while folks have already been using larger external 3rd-party or DIY Li-ion-based battery packs successfully for fast recycling.
Now it appears the assertion is false, as Godox made Li-ion powered flashes (V850c, V860c, recently V860n), where a Li-ion cell looking smaller than 4xAA manages to pull out twice as many full-power pops, with faster max recycling time (1.5s), and with the battery not running as hot as standard cells. It will be interesting to see how long it takes canikon speedlights to follow suit.