so battery is at 83% should i charge fully and then check voltage?
83% and you havenāt charged it since that cutout?
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no itās been charging since I got home a couple hours ago, so itās not fully charged quite yet
Oh. Well. I was wondering if the metr reading of 29.5v is correctā¦ Technically that couldnāt happen unless the vesc is not following the cutoff settingsā¦ But charge it full and check voltage, if it is not at 50.4 there may be a battery problem, but doesnāt seem like the case
so the LVC wouldāve brought the board to a slow stop before getting that low?
In theory yes, it wouldāve reduced your max throttle power and stopped completely at the 33.6v level. Although Iām not familiar enough with the ack firmware, I donāt know if it allows it to go past, or if for some reason the metr is reporting the wrong voltage, never heard of that either
Even so, whatās strange is that most BMS will cut completely at 2.5v per cellā¦ I think soome do 2.45v, but most follow 2.5 and to go that low, some safety definitely triggered if metr logged right
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could it have something to do with duty cycle? DC was at 95% when it happened and max DC is set to 95%
I donāt see why that would matterā¦ You didnāt trigger over current faults Iām guessingā¦ I would figure out why your battery voltage got so lowā¦ I suggest go for another ride while paying attention to your battery voltage and see what it is doing. Then verify with a multimeter or another source thatās not metr to see if it is correct
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if itās 40A battery per side, making it 80A max on 60A BMS you couldāve easily tripped the BMS and the low voltage reading in the logs is just the voltage drop from it tripping and cutting power
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Its close but in reality its almost impossible to hit max erpm unless you are hurtling downhill or bench testing. This happened going up hill so we can discount that as improbable.
I am leaning toward a remote cut out issue.
@whaddys
Tim, what did the board actually do when you got the cut out? Brake hard or just lose power?
Bear in mind that a cut out under full throttle when you are leaning forward can feel like a braking episode and if it takes you fully by surprise it can lead to a superman event.
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It was more like a little blip that threw me off to the side, so not an actual brake. Made me wobble bad but I recovered.
Just for testing, at 90% battery, multimeter vs, metr data
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But his draw right before the shutoff didnāt exceed 30Aā¦ But at the same time his battery voltage dippedā¦ That was right when he went full throttleā¦ Couldāve been over current or lvc? But youād think if it was BMS over current, it would happen more often when he goes full throttle
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Yeah itās very hard to pin downā¦It only happens when Iām going full throttle continuously. So like in this last instance it was uphill and I was experiencing sag so I was going 28mph rather than the 38mph this board is capable of. Only reason it hasnāt happened when Iām going 38mph full throttle is because thatās too terrifying for me and I only hang out at that speed for a second or 2, and donāt go full throttle continuously at that speed. So it feels like it has something to do with putting the battery under high stress, but according to matr Iām only pulling 34ish amps which isnāt crazy, right?
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Could the blip have been the low voltage soft dropping duty cycle from 95 to 65ish? Or metr picked up last read voltage as the vescs cutting power as the hard lower was hit?
I definitely donāt have the experience. But those settings seem higher than I thought recommended for 4.12. Erpm is close but I see the point, going uphill not likely. Lot of current going through them
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Using sensors? Could be an over temp on one motor which would explain the side jerk.
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sensorless and I touched the motors, they were only slightly watm
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Thatās the thing that I canāt make a conclusive statement on. His battery voltage was low but not low low before the cut, but a few seconds before it dips to below LVC level then cuts, then recovers. I cannot tell if the BMS cut or VESC didā¦
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If it was something to do with pulling too many amps, how would I adjust my settings to not tax the battery so hard? Just change the max battery amps setting? So weird because metr only read 35A goddamnit
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If BMS cuts at 60A, set each box to 30A battery maxā¦ This does not affect motor amps, you can leave those
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Long shot but worth exploring.
The lack of fault logs is still steering me towards a remote or bms issue but we have yet to determine whether its a discharge unit.
You would see a log if it was a vesc fault. Bms would only show data on the metr not a fault
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