I may have just caused a short in the charging port for my build and now I’m horrified to see if my battery still works or if it’s bricked. For a bit of background, I just started my first DIY esk8 project and ordered most of my parts off mboards (12s4p battery with BMS, 6368 motors, stormcore, etc.). I think I may have touched the hex nut used to tighten the charging port into a hole in the enclosure to an exposed part of the port’s wire. The only components connected were the bms, battery, and port. The port is done for but my main question is will the battery be ok? (I’m screwed if it’s not that thing was $$$) Is it safe to test the battery by plugging it into the stormcore and testing the motors?
You should do more research before you buy things.
You should always fuse the charge port.
Your battery IMHO is likely to be okay, but you need to check it. Measure the voltage of each P-group WITHOUT SHORTING ANYTHING OUT and paste the measurements in here.
Also upload high-resolution photos of the damage and how it’s wired. We can’t help as much if we’re blind. 
1 Like
I tested the voltages of the parallel groups with a multimeter and all of them were 3.496V besides a couple exceptions which were 3.5V.
The second image shows the wires connected to the charging port which I removed and threw out. I think the battery survived but I’m not sure about the BMS. How can I test to see if the BMS isn’t bricked? Should I just try charging the battery when the new charging port arrives?
1 Like
Yeah, it’s probably fine.
The phase wires can be in any order, just make sure after you do the motor detections that you don’t change the order unless you do another motor detection. (if using sensors)
Where can I find a fuse that would connect to the 4mm bullet connectors on the end of the charging port? Also thanks for the quick responses!
You don’t; you just solder a fuse to the wires then glue it inside the enclosure next to the charge port.
Try doing something like what’s pictured here.
Fuse pigtails are available on Amazon when I last checked. AutoZone or similar retailers also sell them.
My plan is very similar. I’m going to get a couple fuses from Amazon: Amazon.com?encoding=UTF8&ref=ya_aw_oh_bia_dp
Then I’ll solder on a female and male bullet connector tips onto each end of the fuse respectively. Next I’ll plug the fuse into the black wires shown below because I’ve heard it’s adequate to place a single fuse on the negative wires from the charging port.
Any flaws in my logic?
The fuse should be on the charge port though, ideally.
Not really any flaw, except that it’d be a lot better to just get rid of all the connectors and solder the fuse right to those wires, instead of soldering other things there, which then need to be connected to the fuse. You’ve not solved the problem, if you finish soldering, and the fuse still isn’t connected
Always check with a multimeter and fuse 80A to the output (to VESC) and 5A to the input (charging port). I used a 40A fuse in parallel for the output.
For this BMS is a waterproof seal. The only way to check your BMS is to remove the battery first. and check with a multimeter for each wire in the JST connection for the voltage output is all correct. Then plug in the battery and continuously check the voltage on the JST connector if you see a positive or less than 00.25v voltage difference (usually started around 3.9v+ on each cell). Then BMS could be bad.
Want a good BMS and reasonable price. Search for “Smart BMS Bluetooth”. I use it on my board. You can edit all parameters for BMS.