52V 26ah battery stopped working

[elik1111]

I have a triangle 52V battery that had a short in the charging part with a spark. I replaced the connector and could charge the battery again. For first few das I felt a decreased in the bike torque. Then one day the motor totally stoped.
Troubleshooting the bike components, I noticed that the battery powers up while connected to the charger. When the charger is disconnected then front light is still on and the voltmetter shows 58V but trying to start the motor the battery shut of and shows zero volts.
Can anybody figure out if it's the battery fault and what's the Fix? As I remember the battery does not have a BMS.

 

[fechter]

There are several possibilities. First guess would be a bad connection between the battery and the controller that causes the voltage to sag under load enough for the controller to trip on low voltage. Voltage sounds like its OK without load.

It might be worth looking closely at the battery to make sure whether or not it has a BMS. Most would have one. If there is a BMS, several fault conditions could make it trip.

Either way, I'd suggest taking apart the battery connection(s) to the controller and inspecting the contacts. Look for signs of heat.

 

[999zip999]

Sir help us out what bike what battery and maybe what country you might be from a link or a picture and we would not have a problem. Check fuse first cheap stuff first.

 

[999zip999]

It depends on the per cell voltage.

 

[dogman dan]

Whatever the problem really is, the first step of a troubleshoot is looking for bad connections. because of the spark when you connect up, the connection between battery and controller can get flaky, so always look at that plug first thing.

Depending on what that is originally, you might want to replace that plug with one known to last longer with that spark.

 

[elik1111]

Thanks guys, I tested with another battery and it was a battery failure.
Opening the battery I found a burned cell.
I ordered the same cells but now a hard mission is to find somebody who can replace and test the battery in NYC, since I don't have a spot welder.
Any idea who does these kind of things?

 

[fechter]

Can you post a picture of the burned cell?

Do you know who made the battery?

Sounds like you are lucky the whole pack didn't burn up, along with your house.

 

[elik1111]

Here is a pic. It seems as after spark but I m not sure actually if the sale is bad.

 

[fechter]

Looks like something made contact with it there and sparked. The cells may actually be OK but hard to see in the pic.

 

[elik1111]

If cells are OK, which I also believes they are what else can it be. The battery voltage get to 58V with in few minutes and then the charger turns to green as the battery is fully charged but the battery is acruelly is completely discharfed.

 

[fechter]

It would be important to know what shorted the thing out to start with. There should be a piece of metal/wire around somewhere with a burn mark.
I suppose it's possible that was done during manufacturing.

The symptom sounds like the pack is badly out of balance. Try measuring the individual cell voltages directly from the cells. There should be 14 groups to measure. Ideally, they should all be within 0.1v or less.

 

[elik1111]

It happened when by incident, I shortened the pack through the charging port with keys I had i my hand

 

[fechter]

Most likely the BMS is sensing a problem with the voltage on one or more cells and disabling the charge or discharge early.

By measuring each cell individually, we can see if one is out of line with the others. A brief discharge caused by the spark should not be enough to make a problem. But the BMS may have been damaged by it. If all the cells measure OK, then I would suspect a problem with the BMS.

 

[elik1111]

These are the pics

 

[fechter]

Nice looking pack.

The spot where all the heavy black wires attach is the battery negative.
It would be good to measure the voltage of each group and compare. I highly suspect the BMS blew a channel.

 

[elik1111]

Measuring between what and what?

 

[GalFisk]

Measure between the connections that ties one side of a bunch of cells together, and the connections on the other side of the same cells. Note that the connections are staggered, so half of the cells on one side go to one connection, and the other half go to another. If you look closely you'll also see that the cells in each half points in the opposite direction of the other.
Measure all "halves" individually, those are the individual cell groups. Looks like there are 14 in all, and 8 cells in each group, if I've counted correctly.

 

[999zip999]

Start at the neg end as number one. Should be between 2.8 volt to 4.2 volt then write down cell group two and write down like this.

1. 2.85v
2. 3.99v
3. 4.15v

14. Xxx volt
This is to show state of charge. Plus battery voltage and charger voltage. This is the starting point.
You can follow the white bms wires in order to find cell groups in numeral order. 1- 14. Pos is number 14. You can put a piece of tape on the wires 1-14.

 

[elik1111]

I don't know. I see 7 groups of 16 batteries connected to each other with a nickel strip. I can not identify 14 groups.

 

[999zip999]

You have start somewhere. But start. The neg is number one then go to the next parallel group. You count the total number of sense wire and report back. We need data. To help.
1. 3.91v
2. 3.85v
Till you get to the pos end.
It might be good to buy https://endless-sphere.com/forums/viewtopic.php?f=31&t=87300&p=1278995&hilit=Diy+lithium+battery+book#p1278995
Do you have a multi meter?

 

[elik1111]

Yes I have.
But I counted 7 groups and not 14 groups. In each side of the pack each group contains different cells. How do I know where is the minus of the group and where the plus is?
I started to mesure each cell and it shows 4.1 V but I can't notice how the cells are grouped together.

 

[999zip999]

Its a snake. Neg 1 black wires on the other side is pos one same buss is # 2 neg on other side #2pos. Parallel group(s) then series to build voltage. Gives some numbers pack voltage ect. Get some masking tape and a red and black marker.

 

[elik1111]

I understand how the battery is built in theory but not sure about where the pols are in reality.

 

[elik1111]

It could be great if somebody could mark one Group check points on my battery photo

 

[999zip999]

We can only see one side. But start at the black wires with black probe find 4.0v than 8.0v than 12v.
But write like.
1. 4.0v
2. 3.9v


14. Xxx volt
You must be able to figure it out with masking tape a black marker a red marker and your Probe listing all the way from 1 to 14 you're going to have to walk through the door because you want to.
Be carefull no rings on fingers no long silver dangling necklace. It is alive.