BMS defect or unbalanced cells

1

1boris

100 W
Joined
Dec 6, 2013
Messages
214
Hi,
My 36volt 19.2 Ah battery is not charging.I have disconected the bms and also charge the battery 10sec in the discharge pins.
i have measured the battery cells and the highest one are 3.71volt and the lowest was 3.3 volt.
Could this volt difference cause the BMSTo go into sleep mode or is it just defect?
 
It sounds like your battery is out of balance. If you charger is working fine, connect the bms and put the charger on the battery pack and let it charge over night. Out of balance battery packs sometimes take a long time to charge and balance.

:D :bolt:
 
I would like to,but the problem is the battery doesent take charging.The charger is tested on another battery and works very well.
So the question is if the BMS is defect or only in sleep mode.Could a unbalanced battery cause BMS to shut off charging.My highest cell was 3.71v and lowest 3.2v
 
It depends on your BMS. Have you disconnected the BMS power from the battery to try to reset the BMS. (Disconnect the B- wire from the battery.) If it is in some sort of "sleep mode" disconnecting the BMS power should reset the BMS if it is working properly.
Disconnecting the BMS from the battery and the charger for a minute or so, should reset a working BMS.

As for you individual battery cells, they sound out of balance but not ruined.

Do you have a picture of the BMS you can post and battery pack. (Keep the file size under 512k for easier posting and make sure the pictures are in focus.)

:D :bolt:
 
https://photos.app.goo.gl/aim7SfJPnsirn63T9
 
Ok, if you have disconnected the big black BMS ground wire so no electricity was going to the BMS, and upon reconnecting it, and the battery still didn't charge, then something else is the problem. The next step is to do this.

Disconnect the BMS balance lead connector (the connector with the small wires) so you can test the individual battery voltages. Insert your negative probe into the socket with the small black wire and the positive probe into the white wire socket adjacent to the one connected to the small black wire. You are now metering battery number 1. (you can also do this with the connector attached to the BMS, but you must be very-very careful not to touch the probes because you will cause a short. :kff:

Once you have metered battery 1, write down the voltage and then move the positive probe to the next adjacent white wire. Leave the negative probe attached to the little black wire. You are now metering battery number 2. Again, write down the voltage. Once you have metered all the way to the red wire and have written down the voltages, post them here in this kind of format.

1. x.xx volts
2. x.xx volts
3. x.xx volts

Meter all the batteries.

Show us all the voltages. This will help us determine the battery's overall condition.

:D :bolt:
 
I don't see anything in the specs for your BMS that would indicate an "out of balance" hard lock-out.

http://enerpower.de/wp/wp-content/uploads/2018/09/Product-Specifications_ENERpower_BMS10S20A.pdf

If you've verified that the BMS to charging port wiring, and port connections, and connection to charger are sound... As a last ditch effort you could manually charge the low cell groups up and see if it makes a difference and starts charging. Recommending that you discharge a bit lower to leave plenty of charge headroom. Rechecking the voltage levels at that State Of Charge.
 
Thank you all for helping
Batteri cells
1= 3.44v
2= 3.30v
3= 3.28v
4= 3.28v
5= 3.28v
6= 3.71v
7= 3.71v
8= 3.71v
9= 3.71v
10= 3.71v
 
Your battery voltages are out of balance, but not so low as to damage the individual cells. Your low voltage cutoff for that BMS is 2.7v per cell, so your voltages seem high enough that your BMS should function.

The remaining two suspects are the BMS and the charger.

If you charger is working fine, then the answer is your BMS has gone bad.

If you feel the battery pack has enough of a lifespan left in it, contact the manufacture and ask about a BMS replacement. If the price is reasonable enough then get the replacement form them. That way you only have to replace the three big wires and not have to worry about changing the connector with the little wires.

:D :bolt:
 
Battery is only 6mnd so it should be worth a new BMS. Anyway to know if these battery are good quality or fake?
 
dcir testing
 
I would manually balance each single groupe to 4.20V. Than do a discharge cycle,recharge using bulk charger. Repeat 5 times. Then take voltage readings. Maybe they just got out of balance because of leakage current that the BMS drains on certain cell groups over the years. In other words, maybe all DCIR are fine. Just manually balance (do you have an Imax B6 ?) and see how it goes.

Matador
 
Matador said:
I would manually balance each single groupe to 4.20V. Than do a discharge cycle,recharge using bulk charger. Repeat 5 times. Then take voltage readings. Maybe they just got out of balance because of leakage current that the BMS drains on certain cell groups over the years. In other words, maybe all DCIR are fine. Just manually balance (do you have an Imax B6 ?) and see how it goes.

Matador
Click to expand...

Hi,
No,I dont have an imax B6.
Is this ok,or do you suggest another one?
https://hobbyking.com/en_us/imax-b6-50w-5a-charger-discharger-1-6-cells-genuine.html?wrh_pdp=3&___store=en_us
 
Ordered this one,belive it can do dcir testing
https://hobbyking.com/en_us/imax-b6ac-v2-professional-balance-charger-discharger.html

Also ordered a new BMS
 
That one is fine. Just be careful when charging individual battery cells so not to short the other cells.

:D :bolt:
 
I have manually balanced my pack since I got it, without a BMS. The chemistry is real stable as long as they dont get too low. I have used everything from little cell phone chargers, to mini 3S rc chargers, to a full on 12V on 1S carefully monitoring it, to 20.50V on 1S, to discharging using 10awg solid wire (with insulation) for a quick millisecond, to using NiCd chargers on Li-Ion. Again baby sitting it. All depends on how far apart everything is, if there are groups close together but still out of wack.
 
1boris said:
Matador said:
I would manually balance each single groupe to 4.20V. Than do a discharge cycle,recharge using bulk charger. Repeat 5 times. Then take voltage readings. Maybe they just got out of balance because of leakage current that the BMS drains on certain cell groups over the years. In other words, maybe all DCIR are fine. Just manually balance (do you have an Imax B6 ?) and see how it goes.

Matador
Click to expand...

Hi,
No,I dont have an imax B6.
Is this ok,or do you suggest another one?
https://hobbyking.com/en_us/imax-b6-50w-5a-charger-discharger-1-6-cells-genuine.html?wrh_pdp=3&___store=en_us
Click to expand...

This is actually a knock-off of the guenui e ImaxB6. Should work fine. However, sometimes these fake knock-off are not calibrated to the correct voltages. Double check the voltage with a multimeter, just to make sure your knock off charger does not overcharge your cells (otherwise send it back to hobby king for replacement while you can still do it). Most likely you'll be fine.
 
Any easy explanation on how to balance charge my 10s 6p battery with an Imax B6
 
charge each parallel group

as single lipo cell to 4.20v
 
ok,but I am not sure where to connect the charger to each cell.should I just follow the wires from the bms to where it connect on the battery and connect the charger there?
 
Yeah you gotta know what your doing when you work on batteries and LiPo.
Basically, you got two main wires, pos+ and neg+ that are thick gauge. Then there will be smaller wires which are you balance wires, which dis/charge that parallel group. 3S4P, 3 in series, with 4 groups in parallel.
main neg (black)
1234
| balance A small wire
1234
| balance B small wire
1234
main pos (red)

to charge balance A, you'd connect red pos wire to balance A, and black neg to main neg (black) and repeat for balance B, meaning now you connect balance A small wire and balance B small wire to charge balance B.

Know what you are doing FIRST!
 
markz said:
Yeah you gotta know what your doing when you work on batteries and LiPo.
Basically, you got two main wires, pos+ and neg+ that are thick gauge. Then there will be smaller wires which are you balance wires, which dis/charge that parallel group. 3S4P, 3 in series, with 4 groups in parallel.
main neg (black)
1234
| balance A small wire
1234
| balance B small wire
1234
main pos (red)

to charge balance A, you'd connect red pos wire to balance A, and black neg to main neg (black) and repeat for balance B, meaning now you connect balance A small wire and balance B small wire to charge balance B.

Know what you are doing FIRST!
Click to expand...

yes,thats the problem,I dont know what I am doing.somebody should make a youtube video of this.Must be a common problem
 
if my cells are unbalanced and i just plug my bulk charger when certain group of cells reach 4.20 volt will it damage them to let the charger charge the other group of unbalanced cells ? or should i let it charge until all groups are at 4.2 volt ..?
 
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