Wait so if I was going downhill with the throttle off, would I have a problem? I don’t wanna accidentally fry my electronics
Find out what 60k eRPM translates to in speed on your setup. It should be faster than you’re comfortable going on the board. I don’t believe it’ll fry your VESC as it’s not supplying current to the motors when you’re going downhill like that, but I definitely don’t know for sure.
Hm alright. Sorry noob question but how would I find out how fast that is? And would the 12s with the 4 5000 packs give me more range overall?
Plug in your setup to find speed/erpm. Your range is dependent on your watt hours. Ah x voltage = watt hours. So the more the further you’ll go.
So basically you’re saying that with the 4x 3s packs, since it is a total of 20000mah, or 20ah, 204.212 = total wh?
So for 12s, 20*44.4 = 888 wh?
and for the 10s, 10*36 =720 ?
Any idea how many miles that translates to roughly?
The esk8 calc says my weighted speed with 12s is 30.98mph
4x 3s packs in series = 12s 5000mah 4x 3 packs in parallel = 3s 20000mah
You don’t get both by putting it in series. 12s x 5000 mah = 222wh. You can estimate 10wh per kilometer for about 22km range.
I run 12s on 200kv for my personal boards but they a geared to reach well over 40 mph so not a big chance that I will ever overrun the erpm by coasting. It is a different story for a board geared only to reach 25 to 30 mph, you need a little headroom to keep things happy.
@chaka Oh okay, what’s your gearing ratio and wheel size? I have 16-36 from the TB kit and 83mm wheels.
You mean headroom for the VESC voltage wise?
@Jinra Ah okay that makes more sense. Thanks!
You can exceed the Erpm limit on paper and not have a problem during normal operation because you won’t spin the motor fast enough to top it out. Just remember, if you flip your board over on the bench and pull the trigger, it will top out right away And you might fry it that way
@Namasaki That seems logical, would the VESC stop increasing the speed at the 60,000 Erpm or would it just continue spinning until it blew itself up?
I think that depends on if you set the limit to 60k in bldc tool. @chaka is more of an expert when it comes to Vescs Mayb he can give a more definitive answer.
@Namasaki And that limit is just a theoretical one or the limit of the bearings?
There is a setting in the bldc tool for max erpm.
Good point. Going downhill it’s easy to exceed your typical speed = >60k ERPM and kapow dead DRV if unlucky.
Another great way to kill your DRV is on the bench - so don’t full throttle and brake hard. boom dead DRV, then you grab another VESC to re-test because we all like to confirm we’re idiots and kill a second DRV… :facepalm:
The general consensus is (for street not mountainboard) is 10Wh=1km. So 88km/54mi and 72km/44mi. hard acceleration, hills, and weight of rider major impact.
I think this is more of an issue on FOC. I went crazy full acceleration and braking on the bench to diagnose a separate issue and haven’t had any issues on BLDC. I am using a rock solid Ollin VESC 4.12 though. I’ve only heard some stories on how full throttle FOC on bench has burned DRVs
This was BLDC before @chaka let us know ERPM limit of 60k was the issue. I was bench testing 200kv/190kv on 12s. Just hammering hard accel/brake - not good. Likely older hardware too like 4.8 iirc.
just cautionary - gentle on the bench is a good idea.
@sl33py Yeah that would be very unfortunate haha I
I’m gonna be using a torque boards VESC 4.12