LiPo 6S BMS Balance Charging Problems

Let me explain my situation first; I’m working on building my Electric Longboard and at the moment I’m working on the battery for it. Currently I’m trying to use 2 3S 5Ah LiPo’s in series to drive my board and I’m trying to setup the BMS for it. Anyways right now I’m trying to charge the battery through the BMS and I’m having some trouble doing so. First, when I plug the B+ and B- terminals into the main leads of the LiPo and give 25.2V to the P+ and P- terminals it draws current and starts charging the battery, great! Problem is when I plug the balance cable into the BMS, it immediately stops drawing any current to charge the LiPo. When I remove the balance plug it then immediately starts drawing current again. As you can see this is a big problem as the BMS needs to be able to balance the cells as well. If anybody has any ideas on why it’s doing this please let me know!

Link to BMS on AliExpress:

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How can a 6S battery result in a 5S balancer cable? I know that BMSs usually omit the ground wire but that should still leave 6 cables to hook up to the BMS

This bms uses bothe the - and + for balancing with the 5 cables for inbeteeen the cells

I also have this bms but haven’t wired it up yet.

@2-alex-2 yeah I have everything wired up correctly, I think, but I’m still having these problems. I’ve checked the cells on the balance leads and they all add up to the right voltages, it’s just not charging it when the balance lead is connected.

Have you wired the balance leaded the right way

I’m pretty much 100% sure I have but, can you see any problems with it?

Yeah I just went over the balance leads and there definitely properly connected… I think the BMS may just be broken.

From both - should be from the bottom of the balance lead. Over next day or so I will be wiring mine up but first I’m testing what D- is for as I think that should be the discharge - not P- so got the check first.

@2-alex-2 HEY! So I figured out my problem! I needed to be giving it 26V on the P+ and D- NOT P- terminals! At ~26.1V it draws around 5A though changing the voltage will change how much current it draws.

For charging or discharging as I was in contact with the seller and he garanteed me that D- doesn’t need to be used. So I have borrowed a voltage regulator to try and figur out everything.

What voltage is the battery out as the over voltage might have kicked in or have you discharged it first.

@2-alex-2 are you using the same BMS as I am? All I know is that using D- is working for me so I’m fine with that lol.

Yea I have the 5a version but haven’t finished wiring it up. So what do you have where? As I was going to wire up B-/B+ battery then P-/P+ for charging then have a led indicator attached to D- as a discharge which should then indicate weather one cell is down.

As ther two side on the bms looks like there is a hvc and a lvc which I thin D- is the lvc and P- is the hvc

I was originally following @VladPomogaev instructable HERE and he was using the 5A version so there might be a difference between the two other than the amperage it can handle.

Here is a pic of how I have not wired up now.

Ok have just soldered mine all up and the smd next to the balance plug get really hot do yours do this ?

@2-alex-2 yeah the SMD resistors are getting very hot on mine to but that’s because it’s fully charged. I don’t actually think that I shoiuld be using the D- terminal because it’s not properly driving the gates of the MOSFET and there getting very hot. I think that my BMS may be broken… So don’t use the D- port because I also don’t know if it will stop charging when the LiPo is full.

Yea think I had a balance lead wrong that why mine were getting hot. But D- does stop on lvc but I will only be using a led indicator on D- and charge through P-/P+

Would you mind showing a picture of how your BMS is wired with the LED?

@2-alex-2 what do you mean by lvc and hvc?