Probably part of why you dont see many evolve boards going up in flames / cutoff related streetface
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No but you can stop it from getting over discharged and causing a fire 
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You raise valid points, but I’m not concerned about ‘saving’ p groups, more concerned that if a p group failed while running a discharge bms, you would get instant cutoff?
In the same circumstance, if the VESC was in control, you may still have a chance to wind the throttle down gently and apply brakes. Battery might be cooked but rider might still be alive.
Same goes for overdischarge… a discharge bms would just cut you to your knees if you pushed it beyond its limits… the VESC could wind you back slowly…
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Can over-discharge really cause fire?
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I’m not disputing that having the VESC limp mode or something is a potentially useful feature. I’m just trying to understand what we’d actually be getting by that. It would be great if we could get the situations listed when something goes wrong in the battery pack that the BMS can detect and it would get substantially worse if you keep riding. Such as “P-group died. Its voltage dropped significantly (can be detected by BMS). If you keep riding, it may cause fire.”
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Over discharge, over regen, and loss of p group i think are the 3 big ones.
In any of those circumstances, a discharge BMS would have you eating street.
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Imagine that you have a full charged pack that has one p group with a high resistance short, that p group has drained is self to 0v (this happened to me before).
Overall pack voltage is fine so a bypass board would allow you to ride. As you push current thought the pack your reverse charging the dead p group.
I’m fairly sure that putting high current the wrong way through a lithium battery could cause a fire.
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@mackann you are planning on putting these into consumer boards aren’t you? VESC implementation is something that you of all people should be campaigning for… that is if you aren’t already 
So easy to simulate take 1 cell out of a pack that p group with the missing cell will discharge faster than every other p group
Also if you had a healthy 8p pack and for some reason 4 of those cells became disconnected.
In standard bypass the 4 remaining cells would become over discharged and be permanently damaged, needing replacement.
If we had vesc throttling based off cell values rather than pack voltage then this pack would have been saved. Pack might need repair but not replacement. Also would have been safe for the user, only experiencing gradual power loss like when battery is low.
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We have a VMS but it still needs some more attention on the software side.
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Yes a special version of it.
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Removing the huge 250amp BMS for this tiny thing that’s got to be space for a extra 30 cells if not more. How fare do people ride your boards in a day
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It it a combination of 18650 (top) and 20700 (bottom) cells?
how about 13 fuses, have i got you beat?
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40T cells, its 2x 12s3p with two flexi bms, nickelfuse for discharge, normal fuse for discharge and fuse for charge.
No cables and all nickel precut so no sharp corners. Can bus cable, discharge, balance, bms is all intergrated in pcb. You can stack them so you could techical make it 12s9p but very thick. They have a canbus connector between the pcbs to.
Its made to pass the higher certificate UL2272
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I see. On the rendering, the cells in the bottom layer look bigger than the ones on the top layer. Is that just an optical illusion? In the bottom, the cells take the full area of the PCB whereas on the top, there’s still space left for the connectors.
Its exactly the same both. Maybe opticsl illusion.
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Wow! Bioboards will have a battery that is UL listed? I read up on some of the requirements and cost for that
…deffinetly not cheap. Holy cow, this is legit.
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