Li-Ion batteries PCB wiring issues

Thread Starter

Michael67000

Joined Mar 7, 2016
6
Hi,

I've recently bought several PCB's intended to wire on it 3 Li-Ion batteries in serial and to protect them when you charge them. Here is the product :
http://fr.aliexpress.com/item/4A-6A-PCB-BMS-Protected-Board-for-3-Packs-18650-Li-ion-lithium-Battery/32386175340.html?detailNewVersion=1
Unfortunately, the ones I got are different from the pictures as you can see on the photo below. I've wired my batteries on it and I got first 12V at the output, but I couldn't recharge the batteries and after a few hours, my batteries ran down although I haven't wire anything on it.
How is this possible ? Did I wire them wrong ?
I've noticed that my positive output is the one written P- and not P+
Thanks,
MichaelIMG_20160302_153614.jpg
 

Thread Starter

Michael67000

Joined Mar 7, 2016
6
I connected them in the opposite way first (every + and - were changed), but I had 0 V at my output and the seller told me to connect them this way... But now that I have other issues, he told me "he does not know much about his product"
 

blocco a spirale

Joined Jun 18, 2008
1,546
I connected them in the opposite way first (every + and - were changed), but I had 0 V at my output and the seller told me to connect them this way... But now that I have other issues, he told me "he does not know much about his product"
I suspect that the PCB labels are most likely to be correct.
 

GetDeviceInfo

Joined Jun 7, 2009
1,666
Hi,

I've recently bought several PCB's intended to wire on it 3 Li-Ion batteries in serial and to protect them when you charge them. Here is the product :
http://fr.aliexpress.com/item/4A-6A-PCB-BMS-Protected-Board-for-3-Packs-18650-Li-ion-lithium-Battery/32386175340.html?detailNewVersion=1
Unfortunately, the ones I got are different from the pictures as you can see on the photo below. I've wired my batteries on it and I got first 12V at the output, but I couldn't recharge the batteries and after a few hours, my batteries ran down although I haven't wire anything on it.
How is this possible ? Did I wire them wrong ?
I've noticed that my positive output is the one written P- and not P+
Thanks,
MichaelView attachment 102043
You have wired them wrong. You might be able to salvage something, but then again maybe nothing. In cases like this, I would recommend seeking the data sheets for your ICs to see what their operational requirements are, then assess their relationship in the overall circuit.
 

Thread Starter

Michael67000

Joined Mar 7, 2016
6
Yes I also think the labels were inverted... and the seller don't have any data sheets on it. I think I'll ask him to refund me.

Do you guys think I can skip this pcb's in my project, and just solder the 3 batteries in serial with a female DC power jack to charge them ?
 

pebe

Joined Oct 11, 2004
626
I have an identical PCB. It works well and is certainly not 'Chinese junk'.

You have connected all the batteries the wrong way round.. Each of the battery connections has a built-in FET to protect for over-current so it is possible you may have not caused damage to the board, but you may have over-discharged the batteries. . Reverse all battery connections and check the voltage at P+ and P-. If you have volts there all may be OK.

Note that you need to limit the charging current - the PCB does not control that.

Edit: Check that none of your batteries has a low output voltage That would stop the PCB from working because it cuts off the output if the output of any cell falls below approx 2.5V
 
Last edited:

Thread Starter

Michael67000

Joined Mar 7, 2016
6
OK, I've ordered a charger to recharge my batteries. I'll retry asap, but before connecting them this way, I tried in the opposite way (every + and - were interchanged) and I didn't have any voltage at P+ and P-, but maybe one of my batteries were down and that's why it would have stopped the PCB working.
 

Thread Starter

Michael67000

Joined Mar 7, 2016
6
I've finally got my charger and I've continued the tests. I've wired my fully-charged batteries upside-down compared to the photo, I have about 12V between B+ and B- but nothing between P+ and P- which is supposed to be the appropriate output. Would someone have any idea please ?
 

Dodgydave

Joined Jun 22, 2012
8,685
Its the pcb thats faulty, i had exactly the same problem with those two pcbs, replaced it with this board and it now works, it charges and discharges perfectly.


Note you have to connect the batteries correctly, then apply the charger, and then remove the charger and the voltage appears at the p+/- pins.
 
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