BMS defect or unbalanced cells

General Discussion about electric bicycles.
1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

BMS defect or unbalanced cells

Post by 1boris » Feb 25 2019 5:12pm

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?

User avatar
e-beach   1 GW

1 GW
Posts: 3358
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: BMS defect or unbalanced cells

Post by e-beach » Feb 25 2019 7:18pm

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:
Favorite Quotes:
"This is L.A., sugar. There is no 'over the top." Chris Erskine
"At a certain point the entropy wins." Maria Helena Braga

Current Build: ProFlex 757 Expert full suspension. Yescomusa 36v 800w Rear DD, upgraded 10AWG solid core through axle phase wires. 15ah Headway, 1000+ cycles, 80% DOD 30A Tronsung controller.

Past: Trek 4500 Yescomusa 36v 800w front DD.
Liahona, Yescomusa 36v 800w generic front DD.
1992 Trek 800, Yescomusa 800w 36v front DD.

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Feb 25 2019 7:52pm

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

User avatar
e-beach   1 GW

1 GW
Posts: 3358
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: BMS defect or unbalanced cells

Post by e-beach » Feb 25 2019 8:03pm

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:
Favorite Quotes:
"This is L.A., sugar. There is no 'over the top." Chris Erskine
"At a certain point the entropy wins." Maria Helena Braga

Current Build: ProFlex 757 Expert full suspension. Yescomusa 36v 800w Rear DD, upgraded 10AWG solid core through axle phase wires. 15ah Headway, 1000+ cycles, 80% DOD 30A Tronsung controller.

Past: Trek 4500 Yescomusa 36v 800w front DD.
Liahona, Yescomusa 36v 800w generic front DD.
1992 Trek 800, Yescomusa 800w 36v front DD.

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Feb 25 2019 9:15pm

I have reset the BMS but it didnt help.will post pics later


Voltron   10 MW

10 MW
Posts: 2237
Joined: May 02 2013 4:53pm
Location: Santa Barbara CA

Re: BMS defect or unbalanced cells

Post by Voltron » Feb 25 2019 10:23pm

Sure looks corroded on the BMS like it got some water intrusion... Esp at the corner posts.

User avatar
e-beach   1 GW

1 GW
Posts: 3358
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: BMS defect or unbalanced cells

Post by e-beach » Feb 25 2019 11:04pm

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:
Favorite Quotes:
"This is L.A., sugar. There is no 'over the top." Chris Erskine
"At a certain point the entropy wins." Maria Helena Braga

Current Build: ProFlex 757 Expert full suspension. Yescomusa 36v 800w Rear DD, upgraded 10AWG solid core through axle phase wires. 15ah Headway, 1000+ cycles, 80% DOD 30A Tronsung controller.

Past: Trek 4500 Yescomusa 36v 800w front DD.
Liahona, Yescomusa 36v 800w generic front DD.
1992 Trek 800, Yescomusa 800w 36v front DD.

User avatar
TommyCat   1 kW

1 kW
Posts: 394
Joined: Jan 22 2018 8:05pm
Location: North-west Illinois, USA

Re: BMS defect or unbalanced cells

Post by TommyCat » Feb 26 2019 1:13pm

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/uploa ... 10S20A.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.
See my completed Magic Pie V5 rear hub E-Bike build Here!

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Feb 26 2019 6:16pm

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

User avatar
e-beach   1 GW

1 GW
Posts: 3358
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: BMS defect or unbalanced cells

Post by e-beach » Feb 26 2019 6:35pm

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:
Favorite Quotes:
"This is L.A., sugar. There is no 'over the top." Chris Erskine
"At a certain point the entropy wins." Maria Helena Braga

Current Build: ProFlex 757 Expert full suspension. Yescomusa 36v 800w Rear DD, upgraded 10AWG solid core through axle phase wires. 15ah Headway, 1000+ cycles, 80% DOD 30A Tronsung controller.

Past: Trek 4500 Yescomusa 36v 800w front DD.
Liahona, Yescomusa 36v 800w generic front DD.
1992 Trek 800, Yescomusa 800w 36v front DD.

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Feb 26 2019 6:44pm

Battery is only 6mnd so it should be worth a new BMS. Anyway to know if these battery are good quality or fake?

kcuf   100 W

100 W
Posts: 207
Joined: Sep 29 2018 3:21pm

Re: BMS defect or unbalanced cells

Post by kcuf » Feb 26 2019 7:16pm

dcir testing
In 2013 an ad appears on Russia social networks: Интернет-операторы хотели! Работа в шикарном офисе в Ольгино !!!, зарплата 25960 рублей в месяц

User avatar
Matador   10 kW

10 kW
Posts: 918
Joined: Jun 29 2016 10:00pm

Re: BMS defect or unbalanced cells

Post by Matador » Feb 26 2019 7:20pm

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

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Feb 26 2019 8:14pm

Matador wrote:
Feb 26 2019 7:20pm
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
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 ... tore=en_us

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Feb 26 2019 9:20pm

Ordered this one,belive it can do dcir testing
https://hobbyking.com/en_us/imax-b6ac-v ... arger.html

Also ordered a new BMS

User avatar
e-beach   1 GW

1 GW
Posts: 3358
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: BMS defect or unbalanced cells

Post by e-beach » Feb 26 2019 10:07pm

That one is fine. Just be careful when charging individual battery cells so not to short the other cells.

:D :bolt:
Favorite Quotes:
"This is L.A., sugar. There is no 'over the top." Chris Erskine
"At a certain point the entropy wins." Maria Helena Braga

Current Build: ProFlex 757 Expert full suspension. Yescomusa 36v 800w Rear DD, upgraded 10AWG solid core through axle phase wires. 15ah Headway, 1000+ cycles, 80% DOD 30A Tronsung controller.

Past: Trek 4500 Yescomusa 36v 800w front DD.
Liahona, Yescomusa 36v 800w generic front DD.
1992 Trek 800, Yescomusa 800w 36v front DD.

markz   100 GW

100 GW
Posts: 10088
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: BMS defect or unbalanced cells

Post by markz » Feb 27 2019 12:13am

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.

User avatar
Matador   10 kW

10 kW
Posts: 918
Joined: Jun 29 2016 10:00pm

Re: BMS defect or unbalanced cells

Post by Matador » Feb 27 2019 6:42pm

1boris wrote:
Feb 26 2019 8:14pm
Matador wrote:
Feb 26 2019 7:20pm
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
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 ... tore=en_us
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.

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Apr 13 2019 5:28pm

Any easy explanation on how to balance charge my 10s 6p battery with an Imax B6

kcuf   100 W

100 W
Posts: 207
Joined: Sep 29 2018 3:21pm

Re: BMS defect or unbalanced cells

Post by kcuf » Apr 14 2019 8:38am

charge each parallel group

as single lipo cell to 4.20v
In 2013 an ad appears on Russia social networks: Интернет-операторы хотели! Работа в шикарном офисе в Ольгино !!!, зарплата 25960 рублей в месяц

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Apr 14 2019 11:37am

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?

markz   100 GW

100 GW
Posts: 10088
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: BMS defect or unbalanced cells

Post by markz » Apr 14 2019 3:32pm

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!

1boris   100 W

100 W
Posts: 114
Joined: Dec 06 2013 3:46pm

Re: BMS defect or unbalanced cells

Post by 1boris » Apr 14 2019 4:08pm

markz wrote:
Apr 14 2019 3:32pm
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!
yes,thats the problem,I dont know what I am doing.somebody should make a youtube video of this.Must be a common problem

CanadianKid   1 mW

1 mW
Posts: 15
Joined: Sep 10 2019 3:00pm

Re: BMS defect or unbalanced cells

Post by CanadianKid » Oct 07 2019 9:37pm

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 ..?

Post Reply