What’s the exact model of bms? Pic of the sticker and ill post up the wiring diagram. The balance leads need to be adjusted either by landing multiple on one group or adding jumpers/soldering the back of the header connector to get it right
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https://www.amazon.com/dp/B0D6VBSYTX?ref=ppx_yo2ov_dt_b_fed_asin_title
It’s model no. JBD17S005 V1.6, as delivered
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ok so you can do this two ways - run jumpers 9-16 to pgroup 9 or you can take the insulating sheet off the back of the bms and solder a jumper across the 9-16 pins on the back. either way will work and fix ya up. just double check yourself here and make sure you got it correct as shorting or miswiring can brick your fancy new bms.
also if you are just doing 10s, the model SP14S004 is newer and smaller and cheaper. up to 50a charging and discharging before you need to go up in form factor. only does up to 14s though so keep that in mind.
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Thanks a ton! I had no idea about this. I did actually order a couple SP14S004 models to try before this, but the volt readings had a lot of noise for some reason, on both units. As in, the readout on the app kept jumping around by up to 0.1V/cell. Could also be the same wiring problem, I suppose.
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You’re correct. the 14s ones, because the wiring uses the last group and preceding un used groups will read wonky but the software will keep the correct cell count. The 17 will add a group because it uses the second to last and has to invent a place for the last voltage reading. All will be wonky until the balance leads are sorted out. I did have one weird one from the factory but dozens of good one so i didn’t even try to return it - and it was a communication problem with the android app so maybe a bad Bluetooth. So cheap i just swapped it out and tossed it 
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Aight, cool beans
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It’s actually quite loose I can fit a second idler on the other side in the slack and I can take it on and off in one go by hand.
I might just have to accept the belt constantly pushing against the side of the pulley and it coming most of the way off when I reverse bc getting even that takes a couple tries. I have tried so many configurations of different screws, washers and bearings just a single one in the centre or 3 going the full width of the belt. And putting it in different places.
I’m making gears anyway soon hopefully, just not sure on a few things with that too.
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Fyi, the OverkillSolar phone app is compatible with LLT/JBD, and has cell voltage calibration that is written to the bms AFAIK:
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Some manual balancing later, and everything is sorted out. Thanks again, banana man
Keywords so other people can find this issue: JBD BMS wrong voltage Bad reading Wiring diagram Unbalanced Not the same as multimeter
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Just since this seems to be the random everything chat thread…
Anyone in WI? Still trying to find someone’s board to ride just to see how it goes lok
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How low can I drain my 12s2p battery to? Is there some percentage/voltage I shouldn’t let it go past?
What cells? In most cases with standard lithium ion cells, you don’t want to go below 2.5 V per cell, so 30 V for 12s, but it does depend on the specific cells. Also, if you want to be conservative/safe 2.8 V to 3.0 V per cell or 33.6 V to 36 V for the pack is probably better.
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This should be regarded as the ABSOLUTE floor, with the intention of never reaching it IMO.
If you look at the discharge curves of most of the cells we use, the curve turns dramatically towards the floor after about 3v, meaning there is barely any useable energy after that and the energy that is there is used incredibly quickly.
@Dnollie you can set voltage cutoffs in vesc tool but it won’t stop idle drain on your battery, you’ll need to keep an eye on that.
I’d suggest setting your cutoff start to 36v (3v per cell) and cutoff end to 33.6V (2.8v per cell) and if you ever do run the pack that low, i’d suggest charging it back up a bit shortly after use, to avoid any idle drain issues taking it even lower.
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Those are what it is set to. I never really knew that, all the range I would get is purely in the 50.4v-33v range?
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Yes, there is nothing meaningful left in the cell after about 2.8v except it’s last shreds of life.
I don’t know what cells you are using but see the above discharge curve for p42a. The chart doesn’t even go below 2.8v and if you wanted to be conservative, you’d probably look at setting your cutoffs to something like 3.4v (where it really starts to turn towards the floor) soft cutoff and 3v hard cutoff.
In reality after about 3.4v per cell your performance will drop significantly and you won’t have much ride time left.
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So does that red line showing the batteries percentage show all the way to zero, or just to the set cutoff voltage?
Absolutely no idea, i’ll never own a flipsky product again in my life. But it has the voltage displayed there, so should give you an idea.
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Generally 2.8V per cell is considered a good cutoff that maximizes range while minimizing cell degradation.
If pack lifespan is a priority, set your cutoff to 3V or even 3.1V per cell.
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I’m in Milwaukee. Our group has guys who ride everything: one-wheels, EUCs, e-bikes, and esk8. We have a Telegram group, “MKEsk8 Group Ride.”
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