Also check soft cutoff
Nah no smart BMS. I can’t find soft cut off in VESC. What’s that do exactly?
I can see mosfet, motor and battery voltage cut-offs. I suspect it could be the mosfet or motor getting warm that’s reducing power? Which might explain why its zippier now that it’s had time to cool down?
I might try a few runs with VESC RT running and see what gets warm.
Let me check vesc tool and get back to you. It’s been a while.
Voltage cutoff start could be set at 3,4 imo. 3.3 for end.
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No, as long as the BMS situation is the same. (Such as, both batteries are discharging through a built-in BMS)
I would not try this, as it’s likely not the problem, and can destroy batteries.
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It honestly sounds like the ESC is getting hot. Does it have a heatsink?
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G’day mate! Dunno if you remember but you walked me through resetting this board completely after I accidentally wiped the VESC settings. Legend ha ha.
Anyway - I don’t know if it has a heat sink. It’s an off the shelf 2021 single motor BKB so unless that sort of thing normally comes with off the shelf kit boards it probably wouldn’t have one. Here’s a photo of the internals - I can’t see anything that would soak up heat
I’m with @b264 here. I think it’s heat soak on your controller, motor or both after climbing that hill. That would cause the controller to drastically reduce power and has nothing to do with your battery. Heat sink your controller and I’d bet you’ll see improved performance.
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I’m having this same issue on a 10s2p build… 
getting a battery percentage of 2-300%… if you find a fix lmk…
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Yes, you’re definitely hitting your ESC thermal soak limit.
That will happen with a 4.12 style single VESC like that.
There’s not much you can do to fix it. None of these suggestions will work.
You could turn down your battery max a bit to 15A but the performance on the hill will be bad, and it likely won’t even be enough to prevent it from reaching its max temperature.
I would NOT turn up the maximum allowed ESC FET temperatures.
Buying a used FOCBOX 1.6 or 1.7 would help a lot.
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Hmm righto. I’ll try to confirm esc throttling today with RT data.
If I switch to focbox I assume I have to reprogram everything? New remote? Is 1.6 or 1.7 the best option here? What about newer VESC models.
Where would I find a 1.7?
yes (kinda) Many options can just be copy pasted
no, current one can be reused.
1.7 (or completely different esc)
Not new from shop, only used/new from private sellers. You need to ask if its a 1.6 or 1.7 (they need to open up the cover to see)
For a single drive, 1.6 and 1.7 are identical.
For a dual drive, 1.7 is slightly better in that it has a tiny bit more safety circuitry for tolerating a miswiring without frying the CAN chip. But if wired correctly, they are are the same.
So for a single drive, a 1.6 might be slightly easier to find and/or slightly cheaper, but we’re talking by razor thin margins here.
The thing I wouldn’t suggest is a 1.3. There are significant improvements between the 1.3 and 1.6. The 1.3 also wasn’t called FOCBOX, it was called VESCX 1.3.
If you meant to ask “Is FOCBOX the best option here?” the answer is no, probably not. Assuming cost is no factor, there are much better things available.
If cost is a factor, there are also a lot of other ESCs that will work. But there are several of these on the used market right now you could probably snag for less and they will work GREAT for what you need.
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I wouldn’t say cost isn’t a factor but what ballpark are we in here? Given my very limited programming knowledge is there any option that would allow me to backup current settings in VESC tool, install new VESC and then restore settings to the new VESC? Or is that a no-no in general?
Before I start throwing money at this problem here’s some RT data from the ride home. The vertical line on the charts is the top of the hill in question, and I arrived home at the 500 second mark
Current settings are
Motor amp Max 50
Battery amp Max 45
Battery voltage cutoff start 36 end 34
Mosfet temp cutoff start 85 end 100
Motor temp cutoff start 85 end 100
What are you guys seeing here? The mosfet temp doesn’t seem to ever get over 81, so that doesn’t actually look like the issue? The motor temp reads as -86 so I don’t think it even has temp sensors? Is it battery voltage cutoffs that’s throttling performance? There seems to be a lot of voltage sag - is that a normal amount?
Also I’m wondering why battery amps never gets over low 30s when it’s set to 45? At the time I’m trying to climb the hill it’s down around 20A.
Just thinking about voltage cut-offs and sag- I note the voltage was right down towards 34 there near home, but the battery is indicating still half full and after resting at home for a few minutes voltage was back up to 37. So if you lower the end cut-off to say 28 knowing you have that level of sag, the cell voltage would actually still be about 31 when not under load? Am I thinking about this the right way?
Definitely temp issue. On the last screenshot you throttled after only 5 minutes.
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Isn’t that just showing temp tho? To me the mosfet temp graph just plateaus suddenly but I can’t see what has actually caused the temp to stop rising.
I. E. you can’t see any distinct throttling or drop in any of the other graphs. Notice in the first screenshot there’s no discernible change in battery amp output at the same point in time for instance.
And the fact that the mosfet never actually hits the start temp cutoff of 85 - is that just an expected margin of error in the sensor or software or something?