The Zippy’s have a BMS already in each pack, right? So what charger do you use? What is your top speed?
I’m at a little under 190lbs and my build goals were 10-12 miles (check) and around 25mph top cruising speed (I calculate 24.94mph weighted-- check?).
I’m over the suggested limit. I have torqueboards motor that spins theoretically at 67k rpm at 12s which means 190-200kv? There is a bigger risk going downhill? I plan to get vesc v6 when it’s available
It can be problematic if you are not careful.
Nope - no BMS. You need a regular Lipo charger. On a budget and want simple - i recommend a iMax B6ACv2 - has AC-DC Power supply inside for one plug simplicity. If you want ability to charge more than 5 Amps - and don’t mind some complexity (or can use for other RC hobbies) - check out the iCharger chargers (206b/306b). I have the 306b w/ dual dell server power supplies for 24v 1500w.
To charge multiple batteries - a simple parallel board. Helps to occasionally charge individually.
Speed is all in the gearing. Not having her board in front of me, i’m not positive of motor gear, but likely:
83mm wheels - 200kv motor - 8s - 14/36 = 21mph. She tops out at around 8mph realistically, but i do ride it every once in a while and it moves along fine w/ me on it (265lbs).
I usually gear for 25mph on my builds (single or dual motor). 8-10s usually and love running 97mm wheels for rough roads (or unattended small children). I gear as low as i can w/ the larger wheels and higher voltage on 190-200kv setups. Run some gear calculators and you should do fine. Don’t go below 13t on the motor on 9mm belts - it will skip. I might not go below 14t on a single, or go at least 12mm or 15mm wide belts.
GL!
So @sprocket12 did you get a new battery pack? I would concur and say this is your limitation. The peanut gallery is getting loud in here 
Oh yeah! I went with two Zippy 8000 mah 4s1p at 30c. I placed them together to make an 8s1p. Plenty of torque. Top speed around 27 mph and i get just under 12 real world miles!
Rebuilding now. We are at around 14" snow and in single digit temperature (F). So i needed something to do. 
@chaka @devin I keep my ERPM pretty low and my Real-world (and anecdotal) experience has been that if I approach or exceed that limit and apply throttle, I just continue to coast. I can hear VESC engaging but it never presents a “braking” effect if I’m beyond ERPM and apply more throttle. I forget which parameter it is in BLDC Tool, but I believe that this behavior is the default.
@treenutter Thats the parameter. When it is disabled then it simply shuts off the VESC. When it is enabled it brakes when it exceeds the MAX ERPM.
@Ackmaniac Ahhh thanks for the reminder. This makes sense to me now… I use FOC mode so I think that this parameter does not engage in the current firmware when in FOC mode. Hence, I haven’t experienced negative torque when exceeding the ERPM. I’m sure there are many other variables that apply, as @devin notes above.
Funny that you mentioned it. I checked the FOC code and i can’t find a limitation of the max ERPM. So it seems that the only limitation is the soft ERPM limit from the application. That could be a bit risky if that value is not set and you run the board on the bench with a 200kv motor and a 12S battery. Because then you get above 60000 ERPM.
So you should make sure that the soft ERPM limit is set in the application to prevent that. It’s also a bit strange that Vedder didn’t implement that.
But you could change the
App Configuration --> PPM --> PID max ERPM to limit the ERPM to 60k?!
That would be only for PID speed control. You need to set the App Configuration --> PPM --> Soft RPM Limit --> ERPM limit start and ERPM limit end. But if you run the VESC via the keyboard in BLDC-Tool you could reach higher speeds than 60000 ERPM. But it depends on the motors kv and the batterys voltage. With a 190kv motor and a 12S Battery you should be careful. But maybe it also doesn’t really hurt the VESC when it is above 60000 ERPM. Who knows?
Hello Chaka,
I have made a 8s3p battery pack made from new VTC5 18650 cells. Voltage is 37V fully charged but max speed is 25kmh and it feels really weak… Range is also not great. Can you think of what went wrong?
Well it would seem you have well over charged your batteries the max voltage per cell is 4.2v what you have said suggests you have charged the cells to 4.6v which is way to high
Pat is right, those cells are being over charged at 37v.
Still, 8s3p is crazy small for an electric skateboard when using 18650 cells. If you want good torque you need a lot of cells. 60 cells seems to be the starting point if you want something that will be powerful throughout the discharge cycle.
I get good results with my 8s5p packs, but I use new cells.
Thats a big jump from 8s3p, you will still get a good deal of voltage sag during acceleration or hill climbing. And when our voltage sags we lose power, less watts. The absolute best setup I have tried is a 10s6p with sanyo 20700 cells. Like I have a freight train pushing me. Hill climbing at speed is where the big packs shine since we are asking for more amps and running around 80 to 90% duty cycle.
True! I meant as a minimum for 8s should be 5p.
