36v-10ah Headway pack dropping voltaje help needed

[contador]

Hi,I have a headway pack 36v-10ah LiFepo4 pack,unused and stored for six months or so charged a couple times during storage period.
Fresh from the charger it shows 43,5 volts,but drops dramatically to 40/40,9 when pluged to the controller and when the throttle is pulled before riding.

When riding, the voltaje drops even faster and the power is cut at 35,5 volts in less than one km.
The sistem is a 350w Nine C,22A controller.
Hope the problem is the charger.(2 amp).When charging the green light turns on in a bout 10/15 minutes ...so I dont know wht to think.

Measuring the voltaje of the series its going to be a hard task because the BMS pins are completely glued,so first i need to make sure the charger is working right ,how do I check that?


Thanks in advance
Santi

 

[dnmun]

cut around the edges of the BMS where it is glued to the inside of the case and see if the BMS will then pull up and out of the case while all the wires are still connected.

if you can do that then you can measure the cell voltages on the underside of the BMS pcb where the sense wire plug is soldered to the pcb.

you can edit voltaje in the thread title too.

 

[velias]

Are you sure thats a headway pack?
I thought headways were all big cylindrical cells?
Can't tell from the photos what the overall pack looks like.

 

[dnmun]

he disappeared. doesn't look like a headway pack to me either. tried to help.

 

[contador]

Hi thanks for reply and sorry I am not able to get on line very often lately.
I purchased the battery from Nine continent factory with some kits and I suppose they are headway because that was the logo printed in the boxes

And because one of them seem to be the one you mention velias.


The battery Im having trouble with is the one in the first picture.

And no Im afraid it will not be possible to measure the individual cell voltages by doing what you suggested dnmum,the BMS is completely stuck,thats why I wanted to test that the charger is working properly.

Thanks again guys

 

[contador]

Finally I could measure the cell voltages following the instructions Dnmun suggested and it is a 10s pack,not 12s.
Still pluged to the charger and when the green light turned on ,all cells show 4,10 volt but one that still remains at 2,6!!
My question is : is that string dead?
I left the battery pluged to the charger to see if it finally balance the uncharged cells...

 

[dogman dan]

That 2.6v cell or cell group is not looking good. 10s? I see at least 11 lights on the bms. One of the cells might need to be read by putting the - voltmeter probe on the main - of the pack.

Disassemble and store the remaining good cells? You have a second pack, and it might need the cells someday.

If the charger is putting out the full voltage you expect, it's good. But an undercharge can happen if you have a funky connection at the DC plug.

 

[dnmun]

it is 11S. you have to get the BMS free of the case by cutting the glue and then take pictures but i think this one has 11 sense wires but cannot be certain because not a good picture. so the B- lead to the BMS is the bottom of cell #1 for the measurement of #1. you need to find a single cell charger. yopu can get the little AC adapter, wall wart, or cellphone charger as they are called. then expose the wires and use them to charge up the single cell.

 

[contador]

Well Dnmun Here is where I measured the voltajes starting from the far right :red probe on the second black on the first ,red on the third black on the second and so on...

 

[dnmun]

yes the B- ground plane is on the right side. it is 11S. so put the black probe on that and the red probe on the first wire out of the sense wire plug which is next to it there in the solder bumps. the circuit current takes off from top of #4.

 

[contador]

Those are the redings:
-4,10
-3,96
-2,73
-4.11
-4,11
-4,11
-4,11
-4,09
-4,11
-4,10
-0,00

It seems that the bad group is slowly rising,since I left the charger pluged overnight and did not unplugged it yet...

 

[dnmun]

where did you measure the 0V?

 

[contador]

red probe on the first soder bump starting from the left hand side/black on the second.
By puting the black on the first and the red on the metal circle beside it at the left end I get a positive reading of 4,1 again..

 

[dnmun]

lets start over. you need to follow normal convention and count from the bottom of the pack to the top. on the right side in your picture there is a broad ground shield with one hole but no wire. that is B- and it is the bottom of cell #1. put the black probe on that and the red probe on the first pin in the sense wire plug, where that first solder bump shows. that is cell #1. measure starting there and go left up the series.

measure between the top solder bump and the hole on the left of it with no solder bump. that is connected to the top of the battery B+ i think so it should measure the same as the top of #11.

measure between adjacent sense wires.

 

[contador]

-4,10
-3,96
-2,73
-4.11
-4,11
-4,11
-4,11
-4,09
-4,11
-4,10
-0,00
-4,18




Yes,sorry dnmunI did not explain myself right (poor english).
The zero value was from the black probe on the 10th solder bump and the red on the 11th,
and the 4,18 from the black probe on the last /top bump and the red on the left hole without solder in it as you adviced.

 

[dnmun]

that's bad.maybe the sense wire to that top cell is broken. you can only hope.

 

[contador]

Sorry to hear that.
Anyway I will try to charge the low cell at the bottom with a cell phone charger,and see what happens.
Should I do it through the solder bumps?

 

[dnmun]

it is unknown if your sense wire is connected to the cell so that has to be established. if the cell is 0V then it is dead.

 

[contador]

Thanks dnmun,
It is the 2,6 volt cell that I wanna try to top up,assuming that the 0,00 cell is due to a damaged sense wire...
Is it worth a try?

 

[999zip999]

You must check on the cell. Most times if a cell is 0.00v it is dead and not to be recharged because of the danger it can cause. You may have to replace that cell or set of 0.00v that make that cell. A better. pic of battery to see the maker of the cells or battery pack. Or who made the pack or where did you get it.

 

[contador]

Thank you all for your replies.
So far all I know is they are pouch cells,will try to get the pack out of the case and then will post better pictures.
The battery should be a Headway (I purchase it from Nine continent China with the rest of the kit,and it seems Headway is the main battery supplier for 9C).
There is a label that says it is LiFepo4 36v-10ah...

 

[contador]

and there was a Headway logo printed in the box,and some familiar cilindrical cells in the back.