Changed BMS now battery will not charge

[Moogster10]

Hi everyone - first time poster - enjoying solving the problems now. Am a bit stuck though

TLDR
1. Battery was not powering the motor
2. Installed a new BMS
3. Motor now works but the battery now does not charge

BMS
https://www.amazon.co.uk/10Series-Prote ... C80&sr=1-3

Battery
https://yosepower.com/collections/e-bik ... ic-bicycle

Suspect it is a BMS issue

Not sure if
A.The BMS is wrong
B. BMS is installed incorrectly
B. Battery has an issue

The voltage across the cells is consistent (3.4V)
There is output from the battery if I bypass the BMS (34V)

The battery is quite run down as I was just using it hence the low voltage.

My thoughts are around taking the BMS off and re-installing but if it is the wrong type of BMS then this might be useless.

Options
- get new BMS
- reinstall BMS
- take off BMS and battery balance instead

Any tips / guidance welcome

 

[Moogster10]

So
This may help - but I still don't actually know what the problem is.

Measuring each pin on the connector (black on B - red working through the pins)
3.47
6.92
10.42
13.90
17.36
20.82
24.3
27.7
31.2
34.9

Measured the charger also - there was 42v coming from that

Measured between black and red terminals on the battery (cutting out BMS) - 34.9v
Measured between red on battery and P- (blue wire) - 34.5v
Measured between red on battery and C (white wire) - 34.5 V

So still not sure what the issue is why its not charging
- is battery asleep?
- problem with where the charger plugs into battery?

Any ideas?

 

[Nealh]

Rather then go thru the connection process of the BMS to the battery, it will be best if you show pics of how ;
1. You have connected the BMS , /B- & B+ to the battery.
2. The C- & C+ charge port/connector wire to the BMS and battery.
3. The P- & P+ discharge port/connector to the BMS and battery.

The discharge and the charge will be separate connectors, one will handle higher discharge current and the other a low charge current. So pics are a must to see if anything is wrong.

The sense wires appear to correctly wired as the voltage increment is correct.

 

[Moogster10]

Please forgive my atrocious soldering..

Image 4 &5 you can see the wiring for C- P- B-

Image 3 - closeup of bms

Image 2 - the thin metal ripped when taking cover off battery

Image 1&6 - going in live end of the battery

Happy to take more photos if that helps
Thanks for the help

 

[soundwave]

try using solder flux as helps the solder flow and get nice shiny joints

 

[Nealh]

Yes the soldering is quite messy, looks like you aren't using good 60/40 lead solder or enough iron heat to get nice fluid bright solder joints.

The charge connector is the round one with thin wires, have you soldered the wires on correctly ? I assume so other wise it would have blown up.
I see you have a fuse holder on the charge line tbh it isn't really needed. Is the fuse intact or over rated ?

Has the white multi balance wire jst been connected when charging has taken place ?

 

[Nealh]

All I can think is either;
1. Charge fuse is blown on battery input line.
2. A bad dry solder joint.
3. The BMS is duff ?

 

[Moogster10]

Thanks everyone
Just to confirm - The only soldering I have done is the black / blue and white wires onto the BMS. Everything else is how the battery was originally setup

So if those wires are in the right place - and nothing else seems too obviously wrong
I will
1. Check fuses
2. Buy a new BMS
3. Do a better soldering job
Thankyou

 

[Moogster10]

Yes the soldering is quite messy, looks like you aren't using good 60/40 lead solder or enough iron heat to get nice fluid bright solder joints.

The charge connector is the round one with thin wires, have you soldered the wires on correctly ? I assume so other wise it would have blown up.
I see you have a fuse holder on the charge line tbh it isn't really needed. Is the fuse intact or over rated ?

Has the white multi balance wire jst been connected when charging has taken place ?

 

[Moogster10]

Yes the white multi charge wire was in place when charging. Should it be?

 

[Nealh]

Though not affecting the charge any discharge is going to be unequal on the cell groups #1 & #10 as the final current discharge is converging/being directed to going thru one cell only.
Once the battery charging issue is sorted I would try and alter the discharge connection.
Ideally on the B- & B+ connection one needs to be a Y connection so the current draw from the the five cells is more equal, split the discharge in to two. Strip 40mm of silicone off each end and nicely flow the lead solder for good coverage (do this off the battery).


As can be seen soldering the discharge this way shows how the current will be more equally taken from all the cells.

 

[Nealh]

Yes the white multi charge wire was in place when charging. Should it be?

Yes.

 

[Nealh]

Add a good nice flow of solder as marked by the four marks and then lay the discharge wires on top and then apply solder iron heat so the two flow together for a nice join, if need be apply more solder at the edge for the heat to transfer better.

 

[Nealh]

As indicated by the Red lines the current share will be more evenly discharged from all cells.
At the mo the current has to pass through just one off tale point which means that one cell is stressed the most.



This diagram shows current share better for the final discharge on the B- & B + cell ends.

 

[Nealh]

Thanks everyone
Just to confirm - The only soldering I have done is the black / blue and white wires onto the BMS. Everything else is how the battery was originally setup

So if those wires are in the right place - and nothing else seems too obviously wrong
I will
1. Check fuses
2. Buy a new BMS
3. Do a better soldering job
Thankyou

Do it in this order .
1, 3 & 2.

Practice the soldering on a separate bit of wire or metal. prime the hot iron tip with 60/40 solder and then apply the hot tip to the wire and then apply the solder, if the temp is right the solder will flow nicely as a silver liquid and then once the heat is removed it should cool as shiny and not a dull colour. For large solder areas use a flatter angled tip and not a pointy one, use a 0.8/1mm dia solder core (if too thin the solder just goes puff up in smoke).

 

[Moogster10]

Tomorrow’s going to be busy
Thankyou

 

[Moogster10]

Just to be clear the discharge wire is black?

 

[Nealh]

Don't rush the job, get the solder flow and temp right then carry out the wire mods to the ends.

All the cell voltages say they are above 3.4v per group so the BMS should switch on,
double check the charge connector solders as well and the fuse on the line.

 

[Nealh]

Just to be clear the discharge wire is black?

Red is the last cell group and main discharge though the Black needs to be equal share as well, it is est practice to do so.

 

[Moogster10]

Quick update

- tested fuses (fine)
- resoldered BMS (shiny silver)
- removed charging connector end and just wired charger to the charge cable together (in case there was a connection issue)

No change
On thing of note is that the charger doesn't heat up at all. Normally it would heat up a bit but there is no heat from it at all when I leave it running.
It still has 42v coming out of the end of it though

New BMS is arriving this week so hopefully its that