Which Controller for My Application?

[Serum]

You might find the answer here;

All the BK/Lehner controllers that suit 18 cells can be used on 20 cells

and the 30 cell controllers can be used on 36 cells

The RPM limit is a matter of time. The 42000 rpm limit is weird, Some contradictions are rising questionmarks in my head at this moment about this;

It's about the hardware rev. rev1 = 12 mhz, rev2 = 24 mhz. The 12mhz= 42k limited. i guess it's a matter of the used transistors/fetts, that can't be used on this frequency, or the 24mhz gives a electronical noise in what way ever.

if you see this and this data/information sheets, you will see that the micro controller is able to kick out some more rpm's.. (Mike is asking BK, when this limit will be gone though)

You need some kind of alarm, that tells you when the lipoly voltage drops bellow the 3V/cell It will shorten the lifespan of your lipo badly if you don't keep a close eye on it.