Smart BMS with xiaoxiang app let discharging easy but not charging.

[serginho007]

Got new 13S smart BMS from here - https://a.aliexpress.com/_uVv9eT.

Connected all yesterday according diagram provided. It's all easy. C1 is to charge and discharge and B1 to battery negative.



Fitted on my bike and done miles to test (about 10). Obviously used positive wire from the pack and C- to connect to controller. All worked perfectly... Until connect a charger (tried a couple of them) and nothing happened, led on charger stays green like if battery would be charged completely.

Measured voltage with multimeter:

Battery pack voltage is 46.4v (the same shows on the xiaoxiang app)
Battery pack voltage is the same with connected charger!!!
Battery pack voltage between C- and positive wire from the pack is 54.7 when charger connected

So, it look like BMS stopping charge coming from the charger to the battery...

Any suggestions?

Thank you for any help.

 

[dfragx]

Hi, can you provide pictures of your connections?
Lets hope something is not correctly connected, that diagram is somewhat confusing but for what looks to me i think its connected as many BMS's by being on the middle of the (-) negative terminal of the battery and leaving the (+) positive terminal untouched except for connecting one balancing wire for that cell group and another wire (+) positive coming from the charger (check if this wire is missing) Let us know. (edited)

 

[serginho007]

Hi, can you provide pictures of your connections?
Lets hope something is not correctly connected, that diagram is somewhat confusing but for what looks to me i think its connected as many BMS's by being on the middle of the (-) negative terminal of the battery and leaving the (+) positive terminal untouched except for connecting one balancing wire for that cell group and another wire (+) positive coming from the charger (check if this wire is missing) Let us know. (edited)

Yes, here are pictures. Had to take off all electrical tape that been used to put all cables nicely as I was hoping that pack will no need to be unwrapped.





If you need more pictures from different angles - please tell, and I will retake...

 

[raresserban]

Hey, sorry for not having an answer to your question, but what "kit" did you use for that pack?Or how exactly did you build it?

One note that comes to mind, did you check the app settings that everything is ok there and it is not something configured incorectly?

 

[serginho007]

Hey, sorry for not having an answer to your question, but what "kit" did you use for that pack?Or how exactly did you build it?

One note that comes to mind, did you check the app settings that everything is ok there and it is not something configured incorectly?

Here is the kit with lots of pictures and videos on YouTube: https://endless-sphere.com/forums/viewtopic.php?f=31&t=88051

This is the second pack using the same BMS. It is just the first custom pack made by one company in China. So, I just made screenshot from "working" BMS app settings to this one. It should work, but I'm still waiting an answer from seller/manufacturer, possibly this BMS is faulty, not sure.

 

[dfragx]

Well everything looks well connected, can you check if voltage and correct polarity is coming into the charging pin on the BMS when you connect the charger?

 

[serginho007]

Yes, everything is correct. BMS looks like faulty. Yesterday new BMS arrived, connected and working perfect. Its shame that faulty BMS can't be returned/refunded as I had to solder copper plates and seller want to accept even faulty BMS with 'modifications'. Next will need to check if MBS is in working condition - then making modification. Experience cost money...

 

[dfragx]

Nice, If you have one to compare you may easily fix it Cheers;D

 

[serginho007]

Nice, If you have one to compare you may easily fix it Cheers;D

Yes, If I would have experience to repair BMS's - then yes. It may need to open and test all components. At some point I’ll do that.

 

[serious_sam]

Its shame that faulty BMS can't be returned/refunded as I had to solder copper plates and seller want to accept even faulty BMS with 'modifications'.

The heat required for adding copper plates could easily be enough to unseat some small component elsewhere.
From my own experience of changing MOSFETs and upgrading copper on Bluetooth BMS, the heat required make it a delicate procedure so other components aren't bumped out of position.

It's possible that the BMS was faulty from the factory, but also possible that you slightly damaged it during the modifications.

Particularly if it's only one bank of MOSFETs not working, it might just be a misaligned resistor or connection to the gate rail. And that might be an easy fix.

 

[serginho007]

Its shame that faulty BMS can't be returned/refunded as I had to solder copper plates and seller want to accept even faulty BMS with 'modifications'.

The heat required for adding copper plates could easily be enough to unseat some small component elsewhere.
From my own experience of changing MOSFETs and upgrading copper on Bluetooth BMS, the heat required make it a delicate procedure so other components aren't bumped out of position.

It's possible that the BMS was faulty from the factory, but also possible that you slightly damaged it during the modifications.

Particularly if it's only one bank of MOSFETs not working, it might just be a misaligned resistor or connection to the gate rail. And that might be an easy fix.

Yes, thanks. Need to find time to test... Maybe even will order one more the same brand/model, so I can compare multimeter reading on both of them, the one is faulty and one in working condition...