Trying to Finish DIY Build - Issues with BMS, VESC, Battery

I started an ambitious first DIY build last year without knowing much about esk8 and of course life got in the way. I’m getting close to finally finish it up now but I ran into a few issues when wiring up the BMS and VESC and I’m hoping to get some advice here.

Relevant specs:

  • 12S4P P42A battery
  • 50.4V, 8A charger
  • TB 6380 190kV motors
  • BN Gear Drives
  • Stormcore 60D
  • FlexiBMS

I basically had everything wired up correctly and had successfully updated / read voltages from the FlexiBMS when I got a little too careless and caused a short while adjusting the soldering job on one of the Battery pack to BMS terminals (:man_facepalming:t3:). There was a quick/bright spark and something popped on the FlexiBMS and that was it. It appears the BMS is damaged (can still connect over USB but there were small sparks when I tried to connect the battery pack leads again), and I’m waiting on feedback from @SimosMCmuffin to see if there is any reworking I can do to fix it (I’m fortunately pretty experienced with SMT rework). Otherwise I am afraid I will need to wait until he has another in stock and wait for it to ship to the US before I can finally finish my board. I would really like to get up and running ASAP, so I’m hoping you guys can help answer some questions on where I can go from here:

  1. Did the brief short across the battery pack terminals potentially damage my battery pack or my VESC which was unfortunately connected at the time? Is there anyway to diagnose if there is lasting damage to my battery? I am hoping the VESC is alright, but I imagine there is no way to tell until I go through the VESC setup process and test everything.

  2. I would like to continue setting up my board and make sure the VESC is alright while I am waiting to fix or purchase a new BMS. While the BMS was working (before it shorted) I was able to get a reading for all of my S groups. They are currently ranging from 3516-3526 mV. Is this enough battery to start the VESC setup process? Should I charge the board first (without a BMS) and manually stop when each S group is around 4100 mV or something like that first?

  3. If I can’t fix the FlexiBMS and I can’t get another shipped out anytime soon, should I start using the board without a BMS until it comes in? I could manually check the balance wires after each charge (pain in the ass but I could do it for a bit), but I’m not sure how to make sure I don’t overcharge it in this case. Are there any other popular references or threads here for helpful information on running without a BMS? Would you guys recommend going for it so I can ride it a handful of times over the next few weeks or is it more likely I will damage my board in the long run?

  4. Any other recommendations on where to go from here?

Thanks in advance guys, can’t wait to finally get out there and start riding!

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Link to the original build post: Some Feedback/Direction on my First DIY Build

Picture of the FlexiBMS… it seems like only one or two components near the battery pack terminals were affected… hoping this could be the case:

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Your vesc and cells will probably be fine.
Bms is dead, will need hot air station

I do have a hot air rework station, and some experience reworking some really really tiny SMT components so I think that should be okay for me if it’s fixable at all :crossed_fingers:t3:

then i dont think there will be much you can’t fix.
You should DRV repairs for the forums! people will thank you :slight_smile:

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they really would!

and when I saw this post I thought “Trying to Finish” perfect name for ANY of my current builds

one comment, the motors are are pretty big for first board - have you ridden much skateboards/longboards? gotta be that guy and suggest full face and proper knee / gloves at least :slight_smile:

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I would certainly be happy to help and pay it forward to the community a bit! What exactly are DRV repairs? Don’t believe I’m familiar with the acronym.

Good point. I do have some experience riding manual longboards but definitely planning on wearing substantially more safety gear for this baby! I wanted to go big, may as well since I’m going through all the trouble of making a highly custom DIY build, but I’m sure the top speed and torque will be way too much for me.

Update on the FlexiBMS issue. With some help from @SimosMCmuffin I think I was able to salvage the board. I was able to solder on a small jumper where a trace was blown and separate/hold everything in place with some super glue and silicone. After connecting the battery, there appeared to be no issues after the initial sparking. Current draw was normal. I checked via USB after hooking up the balance wires and readings all look normal. No faults reporting and my status readout is as follows:

State:3522:3523:3522:3522:3523:3523:3522:3522:3514:3522:3519:3520:42188-42208-42208:0-0-0:0-0-0:299:306:0:notCharging:

Fixed unit:

Sparking after the initial short that I was concerned about at first:

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