Charging port wire broke, attaches to BMS? Solved

[SnowDog2112]

Hello all, I have this question in to the maker of the battery, but am also posting here if someone has a quick answer.. 1. A found broken wire from my charging input port to the battery.. It originates as a black wire connected to the charging port. (calibike 48v 15AH). It heat shrinks to a white extension wire that broke off clean with no trace of where it broke from, other than some where inside the cardboard battery case where the other wires are connected. The main black wire from the battery is connected to the BMS.... So my guess is, this wire, (assuming it's a ground) is connected there as well?? No matter what, looks like I got some work to do to get to where this wire connects with a solder gun.

The other wire from the charging port is red. (I'm assuming positive), It connects to the positive output of the battery. Thanks for any help.

Some further, less pertinent details; This battery has been 100% awesome. I'm at 1500+ miles, 2nd year. (with 4 months down time for winter) and it's still doing it's thing.
I took the bike on an extreme mountain bike trail journey, and took a good spill. and thats where I think did the damage. Since it charged fine yesterday.

It's a good thing this happened because I had been just trusting all the wiring I'd tucked away. On inspection, I just found my 3, wheel-to-controller connections totally melting away and ready to short out and in need of some new connectors.

 

[keithmac]

Can you post a picture?, can you find a solder pad with "C-" written on it?.

 

[SnowDog2112]

Using this schematic.... I'm geting confirmation the wire in question separated from the BMS. So off to remove the battery pack (needs it anyways....time to add theft brackets, home depot here I come).. Pictures coming soon.

 

[SnowDog2112]

Ok after a huge fight, requiring the batter to be completely removed from the bike...I have the wire soldered on. Here's the weird part.... It's like fate was forcing me to do what had been in the back of my mind for a while, disassemble, re-inspect-reassemble better than before.

after all, I'd been running on what was the initial test setup that worked quite well or so I thought:

I had left the screws in at the water bottle mount and as you can see from the pic, 1000 miles of wear and tear was getting down right dangerous. The screws have worn through the bag. a protective layer in the bag, the outer shell of the battery case, and the first layer of coating on one of the cell's.

Along with that a few minor splits in wire insulation here and there I got taped up.

Moral of the story, Newbie's.... especially anyone who copied my build..... check your work after the first few 100 miles!

 

[SnowDog2112]

.. In this pic the white wire has been re-soldered to it's original place. The guitar pic was used to avoid melting the foam backing.

 

[SnowDog2112]

New issue... So I got the battery buttoned back up and charging. It seems to to have reached the end of it's charge, but the charger keeps cycling back and forth from full to charging.

 

[amberwolf]

That's balancing.

 

[SnowDog2112]

Ok 2nd problem... runs good until full throttle.... cuts-off and needs to be turned off for 30 seconds and will power back on but do the same thing. Going to check all my connections again, the rear wheel connections need to get redone...they may be the problem...I found the connectors melted and just taped them back up.

2nd cause may be from when I fished the BMS out of the case a bit to get to the solder spot... maybe I pulled a connector off of the back side. Not sure I couldnt see. But there was something resisting the movement.


As for the last post I made...I mean the battery will recharge ok, but the charger doesnt shut off it keeps on cycling on and off. Pointing to a BMS issue.

 

[SnowDog2112]

That's balancing.

should I keep it charging until it stops? It used to do this, but every few minutes, not on and off every second.

 

[amberwolf]

Most likely it's just normal balancing. You'd have to open up the pack and check all of the individual cell voltages to verify this for sure, but you can also just leave the pack onthe charger till the switching stops.


Regarding melted connectors, this means there was a high resistance at the contacts or crimps (if any), and you should fix that before the heat melts things further. It will probably require replacing the connectors.

(I solder phase wires directly nowadays to prevent this issue, and use large SB50 Anderson connectors on battery wires to ensure good contact with large-gauge supply wires).


Regarding the cutout during operation, if the pack is badly unbalanced, the BMS could shut off during high-current draws due to one or more cells hitting LVC, while other cells are still ok.



It could also be that there is something wrong with the BMS itself, or that the wire that came off doesn't normally go where it now is, but the first step in checking for that is to start by checking the cell voltages.

 

[SnowDog2112]

Latest update for those watching (and a huge thank you, to those that do):

I cleaned up the melted cables to the rear wheel. All 3 direct soldered now. No change in the bikes latest issue. (see above)

So my next area of investigation is back to the battery. I got a confirmation from the battery builder that It's very possible I could have messed up a connector when I tried 2 fish the BMS more forward to get a better soldering angle.

One last area of concern was when I re-taped the battery box back up. I applied some pressure to the front rown of batteries to ease them back into the case more where it looks like they were originally packed. What kind of damage could I have done doing this??

Removing the battery pack now. My feeling is it's a BMS connector issue, which would explain the corresponding charging/balancing hiccup that showed up.

 

[d8veh]

I think that the on-off charging and cutting out under power might be related. I'm thinking that either you wore into that cell and damaged it or when you forced the pack into whatever, you disturbed the welds on the strips that hold the pack together, so some cells are not connected.

You can investigate a bit further quite simply by connecting a voltmeter to the battery to see what happens under load and whether the voltage collapse before it cuts out.

To check the pack, you need to run it until it cuts out under power, then measure the voltage on each pin of the multi-pin connector on the BMS to check the individual cell voltages.

 

[SnowDog2112]

Thanks for the reply...I just took a bunch of pics but their on my phone and a pain to resize and get here.. But here's a really good thing... I'm 99% sure, I FOUND THE PROBLEM!

I cut the top of the bat case open... and the BMS connector looked mostly, OK...but just a little farther back the Ground wire uses an Anderson connector. When I fished the BMS forward I must have popped it apart. cause it was laying there disconnected.

So hopefully I haven't horribly unbalanced my set.

And I peeked under the cover and the cell connectors look straight and intact / untouched. Hoping for the best when I go to recharge the pack!

 

[SnowDog2112]

1st sign of recovery.... success.. I was standing there when the charger went into standby without a hitch, as it's always done. Now I'm letting it stay plugged in for a few extra minutes to see if the BMS kicks in for any needed balancing. So far so good.

Next reassembly and a quick evening test ride if possible.

 

[SnowDog2112]

Quick evening test ride: drum roll please... Success! Ride's like the day I built it. Zipped around the block at speeds too fast for a bike without a headlight light. Good thing for streetlight's.

So what started as a mysteriously broken wire on the BMS, turned out to be a much needed 1500 mile check-up and repair session. Helped me get more familiar with the construction of my battery, and most importantly caught some issues before they became problems.

Thanks to all who contributed.

 

[d8veh]

We love a happy ending!