brushless and A123 questions

[Finnster]

OTOH, you could just run upto 8s A123 on the BK. You could do that, get a cooler motor, like a 11XL or so, adn end up in a better place.

The motor would be more eff, so more power to the ground and less heat, amp draw would be OK for a 1P config, so you could lose some weight over a 10cell pack. A 8S1P pack should weigh less than 650g. I'm now running a 10S A123 pack w/ a 1100 kv motor and everything runs dead stone cold. :) Once you go HV you don't go back.

[highflier]

Originally Posted by Finnster

OTOH, you could just run upto 8s A123 on the BK. You could do that, get a cooler motor, like a 11XL or so, adn end up in a better place.

I don't think so the BK controller is rated to 20NMHI cells right? I thought 6s A123 cells would be the limit
I have thought about 4s2p and getting a 7xl or 8xl motor instead of the 9xl

Eventually I may get another power train and give this one to my wife. Strange as it sounds we go for walks in the park 1-2 miles and bash out E-maxxes on the way. We just carry a spare pack and turn around before the first pack is dead. Funny thing is she has a 100% stock maxx and mine is stock except the motor/controller. I have been running 14.4 volts on the system till now. My system still has more power and the run time is at least 25% longer :)

The 5s2p may be perfect for me, since run time is more importent then top end... However punch is so much fun

Highflier

PS. I am down to 2 different chassis.
FLM ext or a super sized one from RC-Cellar that is extended by 5". Anybody try that one out for bashing.. As a basher which would be more fun..

[Finnster]

Originally Posted by highflier

I don't think so the BK controller is rated to 20NMHI cells right? I thought 6s A123 cells would be the limit
I have thought about 4s2p and getting a 7xl or 8xl motor instead of the 9xl

...

The 5s2p may be perfect for me, since run time is more importent then top end... However punch is so much fun ..

That's if you are figuring the voltage limit @ 1.2V/cell, but NIMH charge to ~1.45V/cell off the charger, which would be ~29V for 20cells. 8S A123 would charge to ~29V. BK is a little dumb tho, that's why few use their controllers anymore, so you'd have to confirm everything. I know for a fact 6S lipo was common on the controllers, tho not sure if anyone ever ran 7S (maybe due the the odd # of cells tho.)

Anyway, running higher V does not mean more top end if you match it to the proper motor w/ lower turns. You are just making power w/ V instead of so many Amps. The end result is less wasted power and less heat. A 8s1p setup would run cooler and longer than a 4s2p setup with a similarly matched motor. You don't need to experiment if you don't want to, just letting you know the option is there.