The info below is directly from the Mamba Maxx Tuning guide. You cant just throw 3s on the 7700. Youll blow up the motor. But, from the recomendations, it sure doesn't seem like they are worried about pushing the 65000 rpm limit of the motor
This is my favorite quote... ''In internal and beta testing, we were unable to find gearing options that would actually thermal the controller when used within spec:''
So in theory, you could gear your truck to have retardedly high top end for some silly speed runs. Granted the acceleration will suck.
Quote:
Where are the “real” limits and what is the fastest?
In internal and beta testing, we were unable to find gearing options that would actually thermal the controller when used within spec:
Max input voltage for ESC: 3s lipo or 12 cell NiMH/NiCah
Max RPM for CM36s motors: 65,000 rpm
4600Kv motor max voltage: 4s
5700Kv motor max voltage: 3s
7700Kv motor max voltage: 2s
The Kv of a motor is the number of rpm’s it will turn per volt of input. So the 4600Kv motor will turn 4,600 rpm per volt of battery. On a 6 cell pack we can presume good cells are holding around 1v per cell, so 6v x 4600Kv = 27,600 motor rpm. If we use a 4s lipo pack, lipos carry about 3.5v per cell under load, so 3.5x 4 = 14v. And 14v x 4600Kv = 64,400 motor rpm . This is right at the top of the motor rpm limit and is OK, but is beyond the voltage limit spec of the ESC and cannot be used.
On the other hand, if we take a 3 cell lipo pack with the 7700Kv motor, that gives us 10.5v x 7700Kv = 80,850 motor rpm which is safe for the ESC, but well over the safe motor rpm limit so it cannot be used either.
So how can you get the most speed? You might think the 7700Kv motor having the highest Kv would automatically allow you to have the fastest setup right? Let’s find out:
7700Kv x 2 cell lipo voltage (max with this motor) = 53,900 motor rpm.
5700Kv x 3 cell lipo voltage (max for the motor and ESC) = 59,800 motor rpm
So the fastest 5700Kv motor setup is actually 6,000 motor rpm faster than the fastest allowable 7700Kv motor setup!
Now if you are racing with 6 cell packs only, then obviously the 7700Kv motor will be the fastest option for you, but we are routinely asked “what is the absolute fastest setup for my car/truck?” The answer in this case, is the 5700Kv motor with a high quality and high output 3 cell lipo pack made for 10th scale cars.
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