I had two 4S 4000mAh 45-90C packs in my E-revo which I gave to my dad now along with the batts. I ran them in parallel for 8000mAh and with 45C discharge ratting they really weren't being challenged in a mildly geared Revo. They ran fine and were always at ambient temperature even as they hit the LVC level. Just like someone else commented above the balance between the cells was a little off during first few cycles but it is spot on now according to dad. All in all I think they are pretty good cells.