MGM controller do I go for amperage or cell count??

[Finnster]

You should just be able to do 7S A123, but 8S is one cell over. Remember that A123s charge to 3.65V, while the controller is rated @ 25.5V max IIRC.

If I was choosing between the two, I would always go for higher V if its an doable option. w/ that hvy a truck w/ and XL motor, you will find you will be fighting motor heat before you hit those current limits. In fact I don't really see the point of the 224/18 controller w/ A123s. Even in 2p they recc no more than 140A max. I would aim for ~120A peak. With 7S A123s, that should be good for over 2300W. If you get a high eff motor, like a neu, that translates to alot of power to the ground. If you go to 9S2P (if you could even fit that on :) ) you have ~3000W. 18cells is alot of frickin cells tho. After a certain power level the batt just starts getting huge.

ZPB has a 7S2P A123 with a neu on his maxx and seems like a very strong setup. Perhaps he could shed some light.

Edit: Kinda contradicted myself there, but point is, more v is always better than amps (224A is silly imo, other than to keep a very cool controller) but you will be practically limited by the A123s if you go too high a cell count with still healthy amp draw. ~14cells is the practical limit else I'd be looking at hi end lipos. ==> 16018 would prolly fit the bill, unless you wanted to really push it to 8-9S on the 16024. How much power do you really want?