bulletfj

Hi, I have a HSP Brontosaurs which i have upgraded from a brushed motor and esc to a brushless motor and esc.

Current Spec:
HSP 3300KV Motor
Hobbywing WP-10BL60-RTR ESC
Tornado RC 3S 5200mah 45c lipo battery
Spur gear - 64T
Pinion gear - 17T

Since i have upgraded to the brushless setup, at full throttle the truck hesitates for 1/2 a second then launches like a beast. This hesitation is more visible when running on grass and less when on the road. On grass from dead stop it sometimes cuts off if its trying to go up a small climb.

Any idea what could be causing this issue guys. Thanks.

DieHarder

Well, I can speak from experience on this one because I have had the same problem with my Hobbywing SC8. For starters though, you are quite daring to run 3S with a 60A ESC. 2S with that unit would be fine, 3S is asking for trouble. Also, on your gearing, the ratio seems a little tall which wouldn't help your case for the 60A ESC. 64 / 17 = 3.76 ratio. I would run closer to 4 or 4.5 with that truck, especially on 3S. The old saying in rock crawling is "volt up, gear down" because it's the best way to get more power from your truck, while putting less strain on the drivetrain. As for your problem with the hesitation, it all leads back to the ESC, which is why I started with that. When you grab full throttle, your motor will pull peak amps from the ESC. Since it is over-geared a bit and running 3S, this peak is even bigger. The spike in amps can stun the ESC, taking a second to process and limit it's output. The hesitation will likely be worse when the system is warmed up, that's how mine was. Again, tall gearing and 3S will cause the little 60A to run quite hot, increasing this hesitation.

My SC8 ESC is a 120A and I ran 2S geared at 56/15 in a 2WD stadium truck on a carpet track. At about 10min in, the hesitation began and would occur when I was launching out of corners. My reverse had an even bigger delay, which I blame on the ESC's processor, since it was overloaded and overheated. After gearing down just 2 teeth on the pinion (56/13), my temps went down a little and the hesitation issues went away.

So I recommend either going to 64/14 maybe 64/13 or getting a bigger ESC, like an 80A or 120A. The 80A would be an improvement, the 120A would be enough and some insurance. Bottom line, I think your ESC is overworked. The 3300kv motor on the other hand was a good choice IMO. That is about the right kv for a good, strong 3S setup.

bulletfj

Hi DieHarder, thank you very much for your explanation and recommendation, it is very much appreciated.

So if i wanted to have a safe setup i should get a 120A ESC and have a 64/13 gearing?

am still very new to the RC world and wanted to understand a few things. Is a ratio of 4 or 4.5 ideal for every setup or does it vary for different trucks. How would i be able to safely say that this motor would go with that ESC and battery with a particular gearing, for example you mentioned a ratio of 4 or 4.5 is recommended - what can i base this on if i am wanting to upgrade another truck.

Thanks.