[jockepocke]

I understand the thundersky spec sheet says to charge to a max voltage of 4,0 v, but I read that many here are only charging to 3,6 or 3,8 v, in order to increase battery life, and seeing as there is only little energy in charging to a higher voltage.

I have now got a good offering on thundersky cells, but I have to choose the right number of cells, and the most important thing is not to go above my controller's max voltage. I have e-mailed the manufacturer, and the cut off voltage is at 140 v, above which the controller will not operate. The controller shut off somtimes with the previous 120-v (60 cells) lead-acid pack when fully charged and regenerating downhills, and I want to avoid controller shut-off during driving, of course. I am also told the controller might get damaged with voltages above 150 v. I was going to use 32 cells to be on the safe side, but maybe I can get as many as 36 if I only charge to 3,8 v?

Does anyone has experience in regeneration voltage for thundersky cells? And suggestion of what voltage to go for?

also anyone can recommend a good charger for these? I would appreciate to be able to set a lot of parameters myself.

 

[jockepocke]

Ok, thanks a lot for the help! seems like I will use 38 batteries, and charge to 3,65 v/cell- then I will stay within limits. 40 cells might be too many.

As the controller will cut power at 140 v, max regen voltage is 140/38=3,68, which should not damage the batteries. This also speaks for using 38 cells and not 36, since 140/36=3,89, far higher, and might overcharge an imbalanced cell... I can of course limit the regen current to prevent voltage form rising too high.