5S or 4S

[hyperasus]

crazyjr is right. Running at part throttle is a very bad idea. 4s really isn't very much for a full size monster truck. In fact. If you have not bought the batteries yet....maybe even consider 6s. If you ran on 4000mah 5s or 6s you would be keeping weight down and efficiency up. Voltage is your friend and it will provide outstanding nitro slaying torque with very low temps and long runtimes. If you was trying to run a Mamba Max ecs then you are stuck with 4s. But with 9920... go for the gold man. Buy 2 4000mah 3s and a very low kv motor. Thats what I'd do anyways.

Another thing. I am just thinking outloud here so someone feel free to correct me if its a bad idea... It sounds like what you want is just enough speed but with very good runtimes. What about going 6s and an L sized can? On 6s it would still run very cool, provide plenty of power for the speeds you want, and provide much better runtimes then an XL motor.