Broken Battery Cable

[Dennis3346]

Hello Everyone,

While on a ride last night I suddenly lost all power to my C965 head unit so I decided to go home and inspect the battery. Apparently, the 10 AWG discharge cable has broken off the printed circuit board of the BMS.
The battery is just a few weeks old so I guess I will try and make the repair but I am not sure how safe it is to open this battery and get to the problem.
I mean, the battery is fully charged so I want to be sure of what I can or should not touch.
I also see white gooey stuff along the break.

Two photos attached.
Advice???

Does anyone have any experience with soldering wires to the BMS?

Thanks,
Dennis
West Lafayette, Indiana

Unit: Bafang BBSHD 48V 1000W Mid Drive Kit
Battery: 50V (14S8PSDI) High Energy-32E, 25.2Ah
Vendor: EM3EV

Close Up Photo...
View attachment 1

Complete Battery Photo...

 

[Jon NCal]

You are right to be cautious as if you short the plus to the minus you could blow things up. Best to contact the vendor with the problem and go from there. Also, put in your location and maybe a more experienced ES member can guide you or repair it and the manufacturer can cover the cost under warranty.

 

[cell_man]

The cable we are looking at here is a 10AWG (5.3mm^2), fine stranded cable. It is the same sort of silicone cable that is used for high power RC stuff and is very flexible for such a large cable. Does it not seem a little strangle for a cable of this type and size to fail after very little usage and for it to go open whilst riding down the road, on a battery that has been used no more than several times? For info, the negative cable has completely split, in quite a clean way, several mm from the PCB. Here is a pic we were provided:

I have seen these cables occasionally wear and fail near the solder point at the PCB, after a year or 2, and lots of usage, as cables do get stiff nearby where they have been soldered. For it to fail almost immediately seems almost implausible.

This was the assessment of the damage, that was relayed to us.

I went to XXXX Electronic (address below) and after looking at the connection it was determined that the original installation of the connection was not 100% plus it was not properly soldered.
Also, he does not believe it can be properly soldered again.
He peeled back many layers to take a good look and felt that there was no realistic way he could make a repair to the connection or if he could it would fail again in a short amount of time.
I am attaching three photos for your review.
How hard and is it safe for me to take it apart and try to replace the BMS unit or do you want to just send me a new battery?

I have suggested that fitting a new BMS is more difficult than soldering the original cable into the PCB. The original cable is simply soldered into a large through hole in the BMS PCB, as is very typical. IME, cleaning up a through hole in a PCB and soldering a new cable, into that hole, is absolutely ok. Re-soldering a cable into a through hole, does not affect the integrity of the termination in any way that i have found, but apparently, my opinion is not universally accepted. I see no signs of a bad solder joint, the solder joint is still intact, all I see is a large cable that has cleanly split.

This level of disassembly was required in order to make the above assessment.

 

[docw009]

Odd break. I could see someone doing that with bad wire stripping technique on solid wire, but he would really had to nick a stranded wire. Maybe too much solder, and it flowed up the wire, so there was no longer any strain relief.

Anyway, pull out the stub, use a solder sucker to clear the thru-hole, reconnect. Fasten that end of the cable so it can't flex. Sure, if you aren't a skilled tech, you could overcook the board. And of course, unless there is a way to break the connection, it's live power, so you cannot short circuit anything or Kaboom.

 

[USAEBIKECO]

Have you tried contacting the vendor for help? They might have better insight how to fix this problem.

 

[Dennis3346]

A big THANK YOU to Paul from EM3EV for all his help in explaining exactly what needed to be done. My local electronic repair shop was able to clean and re-solder the connection on my battery.
All is well and I am back on the road.

 

[cell_man]

That's great, I am really please you were able to get it repaired. I hope the partial refund we made covers your costs and the inconvenience. Please let us know what you need to get the pack patched up and I'll get it sent over

 

[1000w]

Once again, impeccable service by Cellman at EM3ev.
Well done Paul.
Dennis I'm glad that lovely battery is back in service, enjoy.

 

[Tats]

Got to admit that looks like some serious quality parts and assembly there....very nice work indeed