Why do I keep seeing builds wanting to run 12S on a VESC?
I keep seeing people posing they want 12s and want to use a VESC. I’m sure the VESC can only handle 10s.
This is what I keep seeing http://calc.esk8.it/#{"batt-type-lipo":1,"batt-cells":10,"motor-kv":230,"system-efficiency":80,"motor-pulley-teeth":15,"wheel-pulley-teeth":36,"wheel-size":83}|
Why do people want to go that fast. Is everyone just running there systems on race tracks.
Higher voltage typically reduces current draw and heat. The VESC can handle up to 12S, but gets pretty close to hitting the voltage limit in some scenarios. It can also hit the eRPM limit if an inappropriate motor is used.
First of all, that calculator is no where near accurate. I know this because I have run 12s lipos for some time with both dual hub motors and dual 230kv motors with 16/36 belt drive. 90mm wheels Both case using 12s opto Esc’s The highest speed I every got with the hubs on flat ground was 33mph The highest speed I every got with the belt drive motors was 28mph Still I agree with you that 12s is really pushing it. With torque and acceleration that is hard to handle And really pushing the electronics and motors to their limits causing extra heat. I have recently rebuilt my system with 10s and 190kv motors. Top speed is only around 20-23mph because I feel that 20mph is fast enough.
VESC doesn’t handle super high amps either. The More voltage the less amps
True but where do you draw the line? I’m thinking that 10s is the sweet spot.
The calculator merely calculates the values based on a perfect world scenario. It only says what the speeds would be if every component performed at their given ratings. Higher voltage doesn’t necessarily mean more torque or acceleration either. FWIW the calculator is pretty accurate to what I get on my board at 29mph (calculated 31mph).
At 12S though, there may be some losses in efficiency depending on your system, which can lead to lower speeds. @Photorph has gotten 38mph on his board which has a calculated speed of 41mph.
I’d say the calculator is pretty accurate for 10S and below.
I agree with you. Only reason to run 12s is on hubs, or speed demons.
I tested 12s vs 6s on the same dual 230kv belt drive system and there was a lot more torque and acceleration with 12s. 6s was much smoother and more controllable.
When you run 12s, the ESC can supply the power to the motor easier. With lower voltage, current can be bottled necked by BMS/ESC/cable size/etc. I don’t doubt that you had more torque on 12s, but just saying this isn’t always the case.
I think that running 12s with high kv motors has a similar effect on car esc’s and it does on the vesc. More heat. Isn’t that what kills the Drv chip when you exceed the erpm limit, It gets too hot and burns up?
Yea higher speeds = higher heat as well. There’s a point where higher voltage doesn’t reduce heat from current anymore.
I think your right @Jinra that more rpm= more heat. It makes sense because the Esc or Vesc has to switch the magnetism of the motor poles continuously as it spins so the faster it spins the faster the controller’s switches have to work.
I guess it’s safe to say that there are multiple factors causing heat in the system.
For sure! I think it’s somewhat of a misconception that higher voltage = lower heat. That said I believe 10s is the best battery setup for the VESC in its current iteration. Hopefully with 6.0’s release, it’ll be more robust to handle higher voltages and current; not to mention FOC!
I agree with you, 10s seems to be the sweet spot. Now with my new setup, its very smooth and gradual acceleration at the low end of the throttle and fast at the top end of the throttle. waiting for my Vesc’s to come so I can try that setup.
Technical jargon aside…
All I can say is i have a 12s4p running on 16/33 with dual 190 kv r spec motors. After doing runs of 30+ mph continuosly for like a mile straight, I can still touch my motors with my hands and they just feel warm.
are you using Vesc’s ?
Yes, Chaka VESCs
You have 190kv motors which doesn’t go much higher than the eRPM limit, so while you’re motors aren’t turning insanely fast, your gearing is much lower leading to the speeds you’re getting. If you’re going up a lot of hills or against a lot of wind, you’re motors would be pretty toasty.
No hills, either perfectly smooth and flat tarmac or slight downhill on that one mile run where I touched the motors.