SK3 245 + 6S + VESC problem

This is what i mean, i think its not 5M, probably 3M, but not so important anway. Your gear ratio is good. But somehting is not right. How can you make 33km/h with that ratio at 6s. Are you sure your wheels are 82mm. Dunno one or multiple values are wrong. You know what fits the picture, when i calculated for 10s the values fit quite good. DId you run a new motor detection after you deinstalled the sensors?

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I measured speed using Strava, so probably not the most accurate measurement. The road surface if perfect smoothā€¦ I was scared a little, to be honest :slight_smile: Yeah, currently recalculated everything on a calculator and it says I can do 20 km/h max. Yes, I deinstalled sensors and then did a motor detection. Tomorrow will try to reduce start boost to 0.01 and also will reduce motor current max to 50A. Also, do you maybe know what is absolute max? Maybe I hit some maximum and then engine blocks itself?

the motor does no thinking, it is all in the vesc as far as i know, when i did my detection, it was cogging at the end of the test and the recommended method is to increase the duty. Absolut max no, but everyone recommends not to touch it^^

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CC @Colson003

Ok, I solved a problem :slight_smile: I replaced cells in the battery, but BMS was left the same. So, I calculated max current amps based on my batteries (120 amps) while BMS limits max current toā€¦ I donā€™t know the exact value, but I assumed it was around 20 amps (based on similar batteries found on Aliexpress :slight_smile: ). The skateboard works smooth, it isnā€™t scary fast, it doesnā€™t accelerate as a beast, but it is enough to commute every day. Probably will be tested other configurations as well, also in the future, I will install better BMS (thus I should be able to achieve better acceleration and better ride uphill, but for now it is really good as it is). Thank you very much for your support!

The bms will actually cut off if to much power is drawn, it will then recover when current drops again. Iā€™d say thatā€™s why it was cutting out at max acceleration. There are two ways to fix this:

  1. Set your vesc to bat max <20a

  2. Use the bms as charge only, there are lots of threads on this.

Ps. I used to hit 35km/h on my 6s/190kv board lots, just used 83mm and 2:1 ratio

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yes but it doesnt regulate and that cutoff can end badly. okay, was it in a sligh decline?

Ok, Iā€™m back because the problem is back :slight_smile: I would like to ask you about telemetry I pasted below. The first picture presents telemetry when battery max is limited to 10 amps, while the second when battery max is limited to 20 amps. It looks, that BMS cuts off current around 15 amps. It is not enough to run Tuningy SK3 245 KV 6364 motor, isnā€™t it? I would like to mention that problem is back after replacing cables from the motor to VESC. 10amp 20amp

15amps for a bms is not alot especially if you run at 6s and its not bypassed. So you can try to change the bms, take it out of your board or buy one that can handle 60amps so you have headroom. Also i donā€™t rly now why you have a 6s4p configuration, having higher voltage also adds alot to the range, it is not just mAh that influences that. But i mean you can run it, but it will hit the limits fast

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@Benjamin899 @pat.speed thanks for the response, I went with this config only because the original spec was 6s4p and I wanted to use old components etc. However, Iā€™m trying to connect BMS in charge only mode, do you know how to wire this thing? Currently, I have C- connected with charger minus, P- wired with - going to VESC and B- connected to the battery -. Do you know what should I do to archive charge only mode?

have never done that, just search here in the forum or youtube. You should find something.

I will try, thank you :slight_smile:

Yep, connect it in charge only, there are a lot of threads on this

@Benjamin899 @pat.speed Hi, the battery is connected with BMS in charge only mode, but the problem is the same. Currently, Iā€™m able to ride a little, but when I push full throttle the skateboard stops. The same during rading uphill - more throttle means slower ride ride or stops completely. Iā€™m so pissed off, probably there is something with a battery or a motor :confused:

what are your current settings now that you have changed the bms to charge only

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During test ride was as follows:

  • current max/min 60A/-60A
  • battery current max/min 60A/30A

Tomorrow will check with reduced values, however, according to any specification, I see that motor current max is 70A and battery current max is 60A (4 cells in parallel, each of them can handle max discharge 15A without thermal protection).

yeah but your vesc doesnt. when you ride uphill on a single drive you will draw alot of amps. Do you have a focbox with direct fet or just the regular 4.12 vesc. because if so, you should lower your battery max to maybe 40 and that is pushing it, if it is a regular one. and battery min should be negative.

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well, I have the regular 4.12 vesc and the truth is during the ride I noticed on a mobile app that battery current max was ~25Aā€¦ I will reduce all values and will back to you tomorrow. Again Benjamin, thank you for your support!

also on your ride up the hill? i mean the battery max?

yes, ~25A was the max during the ride. I will double check it tomorrow. Also, I really didnā€™t know for VESC a max battery current is ~40A. If so, probably I will think about modifying my battery to 8s3p, to provide more voltage to the engine but first, the skateboard has to start working correctly :slight_smile:

well on paper it is 50a continuous. but the ones with heatsink can take it better than the ones without. there are some here who donā€™t care and let the vesc throttle itself from overheating. I dont know man, your board reacts rly weird.