On road project...need a little help.
 

Ok, I finished converting a Nitro Super RS4 a while back. I ran it using a MM and the 7700 motor. With that combo, I killed the battery (3S1P A123 9.9V) I was using to run it. I figure I over amped the battery. My question is this, I have a 3100kv Medusa 36/60 on the way, and I am going to mate it with a 3s or 4s battery, but I cannot get the calculator to give me the correct speed. Can someone help me out?

One other question, would a 5lb car be to much for a CMS-7700 if powered by a battery that can feed the amps it might want? I want to see 50ish speed. Thanks

7700 x 9.9 = 76,230 rpms = you must be nuts or something.

3100 x 11.1 = 34,410rpms

3100 x 14.8 = 45,880rpms

I wouldnt like to guess the ideal rpm range for use with a smaller motor really, but I'd guess no more than 50,000rpms probably? Just gear accordingly to get you ideal speed, whatever that is.

A 5lb car can be ran by a cc36 motor for sure, but I'd be looking at a much lower kv and higher voltage for better efficiency and temps, say the ~5000kv motor with 3s lipo.

I think a 5lb rig is pushing it for the castle motors, especially the higher kv ones. I ran a 5700 on 3s in a 5lb MT2, it ran pretty hot. I ended up using a heatsink/fan on it to get reasonable temps. I also ran a 4600 in the same rig (3s), temps were not too bad, and a clip on heatsink kept temps in the safe range.

Neil,

I ran the 7700 off a 2s1p A123, thought it was three, and it went pretty good but it wasn't fast enough. I think my 12T brushed would have walked away from it. I was thinking a lower KV with good volts and gear it up. Trying to stay away from the heat and battery killing.

Yeah, higher voltage and lower kv is where its at- results in lower temps through less current draw = easier on the batts. The medusa shoulod yield better results for sure, and allow taller gearing for more speed, so long as the batts can keep up.