48v 10ah battery issue

[mattek]

So my scooter just wont power on. when connected to the charger the light stays green and very quickly blinks red when pulling the cable out of the charging port.

I took apart the battery and hit it with a multimeter.

When connecting the leads to either of the charging port cable terminals, it reads 56.9v and 57v.

When i connected it to the terminal that goes to the controller it reads 48v and then rapidly drops to mV and steadily declines.

Here's the weird part....

When i apply pressure to a specific part of the BMS i can get the controller power cable to read 48v/49v and it will increase to 56.9 if i hold it there. i can also get it to read 48v +when i use a piece of metal to bridge these two nickel strips on the BMS. here's a video

any idea what is going on?

 

[batteryroot]

So my scooter just wont power on. when connected to the charger the light stays green and very quickly blinks red when pulling the cable out of the charging port.

I took apart the battery and hit it with a multimeter.

When connecting the leads to either of the charging port cable terminals, it reads 56.9v and 57v.

When i connected it to the terminal that goes to the controller it reads 48v and then rapidly drops to mV and steadily declines.

Here's the weird part....

When i apply pressure to a specific part of the BMS i can get the controller power cable to read 48v/49v and it will increase to 56.9 if i hold it there. i can also get it to read 48v +when i use a piece of metal to bridge these two nickel strips on the BMS. here's a video

any idea what is going on?

Applying pressure could shift the board if it's warped. Any loose solder joints?

 

[eee291]

You are bypassing the mosfets with that piece of Steel. The BMS has them turned off for a reason: to prevent (further) damage to the battery.
You need to measure each cell row to check if one or more cell rows are under discharged or unbalanced.
If all 13 or 14 rows measure good then it might just be that the BMS can't measure a certain row because of a loose or broken balance wire.

 

[mattek]

You are bypassing the mosfets with that piece of Steel. The BMS has them turned off for a reason: to prevent (further) damage to the battery.
You need to measure each cell row to check if one or more cell rows are under discharged or unbalanced.
If all 13 or 14 rows measure good then it might just be that the BMS can't measure a certain row because of a loose or broken balance wire.

each individual cell measure 4.8 except one that measures 4.7.

Where would i locate the balance wires?

 

[mattek]

Applying pressure could shift the board if it's warped. Any loose solder joints?

ive looked several times and i cant seem to find any.

Does this bms come off easily or is it a pain

 

[amberwolf]

each individual cell measure 4.8 except one that measures 4.7.

Ditto what docw009 said: That's overcharged if it's a real voltage, and you'd want to replace the entire battery at that point, along with the charger that did that to it.

Exactly what they should read depends on the actual cells used; it's likely they are some form of non-lifepo4 (LFP) lithium, and probably charge to 4.2v max, and have 13 cells in series.


I recommend replacing the (probably 9v) battery in your voltmeter, and retesting. A low meter battery makes it read higher than actual. If that doesn't then show you readings lower than 4.2v on each cell, start budgeting for a new ebike battery.

When you do the test, make sure the voltmeter is set to 20 DC Volts so you can see two digits to the right of the decimal point (for instance, 4.17v). If you can only see one, that will look like 4.2v, and cells as different as 4.11v and 4.2v will all read the same, but are actually very different as far as states of charge go, and will perform differently.

Where would i locate the balance wires?

These are the group of thin wires from the BMS to the cells. If the above assumption of non-LFP is correct, there should be 14 of them. If there are more, or less, adjust the instructions as needed and let us know what you actually have.

Measure the voltages between each of these, you'll have 13 voltages when done. Make sure to note which end of the BMS connector you started from so you will know which readings refer to which wires (and thus cell groups).

 

[mattek]

my mistake on the cell voltagnge.

I'm getting 4.36 on each

Ditto what docw009 said: That's overcharged if it's a real voltage, and you'd want to replace the entire battery at that point, along with the charger that did that to it.

Exactly what they should read depends on the actual cells used; it's likely they are some form of non-lifepo4 (LFP) lithium, and probably charge to 4.2v max, and have 13 cells in series.


I recommend replacing the (probably 9v) battery in your voltmeter, and retesting. A low meter battery makes it read higher than actual. If that doesn't then show you readings lower than 4.2v on each cell, start budgeting for a new ebike battery.

When you do the test, make sure the voltmeter is set to 20 DC Volts so you can see two digits to the right of the decimal point (for instance, 4.17v). If you can only see one, that will look like 4.2v, and cells as different as 4.11v and 4.2v will all read the same, but are actually very different as far as states of charge go, and will perform differently.


These are the group of thin wires from the BMS to the cells. If the above assumption of non-LFP is correct, there should be 14 of them. If there are more, or less, adjust the instructions as needed and let us know what you actually have.

Measure the voltages between each of these, you'll have 13 voltages when done. Make sure to note which end of the BMS connector you started from so you will know which readings refer to which wires (and thus cell groups).

the group of wires would be on the underside of the BMS? because I dont see any wires except two tiny black ones that run from the top side of the bms around the side and into the center of the batteries

 

[mattek]

i think my issue here is simply that my battery is over charged.


I woke up one morning to my charger making funny sounds while still plugged in. that was the day it stopped working.

How can i discharge the battery?

 

[amberwolf]

my mistake on the cell voltagnge.

I'm getting 4.36 on each

Assuming you've already changed your multimeter battery, then your cells are overcharged, and is probably why your BMS won't let it work--it has detected the cells are out of limits and possibly damaged, and has disconnected the cells from the outside world to prevent further damage that could lead to a fire.

If you're *certain* of the cell voltages, I'd recommend replacing the entire pack *and charger* since you can't predict when a cell could catastrophically fail. (they might not, but they could, at any time, without any warning).

 

[mattek]

Assuming you've already changed your multimeter battery, then your cells are overcharged, and is probably why your BMS won't let it work--it has detected the cells are out of limits and possibly damaged, and has disconnected the cells from the outside world to prevent further damage that could lead to a fire.

If you're *certain* of the cell voltages, I'd recommend replacing the entire pack *and charger* since you can't predict when a cell could catastrophically fail. (they might not, but they could, at any time, without any warning).

at the moment i dont have the funds to replace the battery. With the scooter being my current method of transportation, i honestly just want it up and running so i can visit my newborn son in the NICU.

Could you please recommend the best way to discharge my battery

 

[E-HP]

i think my issue here is simply that my battery is over charged.


I woke up one morning to my charger making funny sounds while still plugged in. that was the day it stopped working.

How can i discharge the battery?

Are you sure the charger isn’t 52v (14S) instead of 48v?

 

[mattek]

Are you sure the charger isn’t 52v (14S) instead of 48v?

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[E-HP]

Replacement Parts- Plaid Electric Scooter

All parts are final sale with an exchange window of 30 days.

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And the voltage of the charger output was consistent with the description (54.6v)?

 

[mattek]

And the voltage of the charger output was consistent with the description (54.6v)?

Yes

 

[amberwolf]

For reference, see more posts from the OP and replies over here

Help - I dropped my battery charger!

Hi ES folks, Long time, no post. Just looking for help from the collective wisdom here. In a moment of stupidity last night, I dropped my battery charger and it's dead. Pulled it apart, nothing obviously wrong, sadly I didn't have a meter handy to check the mains fuse on the board. The bike is...

endless-sphere.com

 

[rafalg]

So it shouldn't be possible to charge the battery above 54.6v. And you claim that battery is at 56.9
One of these measurements is wrong
Apart from that, I don't think any BMS would disconnect the battery on slight overcharge - that would be stupid to not allow it to discharge. With small overcharge like 4.3 or 4.4V the cells aren't broken, they just age much faster than with standard charging cycle

 

[mattek]

So it shouldn't be possible to charge the battery above 54.6v. And you claim that battery is at 56.9
One of these measurements is wrong
Apart from that, I don't think any BMS would disconnect the battery on slight overcharge - that would be stupid to not allow it to discharge. With small overcharge like 4.3 or 4.4V the cells aren't broken, they just age much faster than with standard charging cycle

the day it stopped working my charger malfunctioned. The LED was no longer on at all and it was making a odd "chugging" sound. I unplugged it from my scooter and tried to power the scooter on and it just did nothing.

Extra info : I know that my power button is working because when i put the multimeter to the power-in cable on the controller and then hold the scooters power button, the voltage left in the controller begins to drain.

So it it possible the block got wet or someone stepped on it and broke it which caused the overcharge?

 

[E-HP]

So it it possible the block got wet or someone stepped on it and broke it which caused the overcharge?

Anything is possible. Do you sleep walk?

 

[mattek]

Did you ever verify that your multimeter is working right? What does it read when placed on the bare charger? 56.4 V or 54.6V? It's kind of tough to get a standard, but a fresh alkaline AA cell is about 1.6V, and a 9V alkaline cell would be 9.6V,.

yes it is functioning properly.

Ok so heres some morew news..

on the bms i habve 3 red wires and 3 black wires. the 3 red wires are all soldered together in a group. The black wires have 2 soldered together that touch a small circle on the BMS and 1 that is a hairline away but is not touching the pad.

these wires are Charge port 1, 2 and the power that goes to the controller.

when i connect my multimeter leads to the red wire group at the BMS and then the group of 2 black charger cables at the BMS I always get a solid 54.6v reading

When I move the black lead to the the the single black wire that would connect to the controller, it briefly reads 48v and then rapidly drops to the mV.

If i connect my controller and then simultaneously touch the black multimeter leads to both the black charger wires and the black controller wire at the BMS, i get a spark and then then the single black controller wire+red wire group reads 54.6v and stays steady.

I am then able to power on my scooter for the first time since this started. But only for 2 seconds before it shuts off and i have to do it again.

Is it possible that this single black wire being so microscopically close to the other 2 is supposed to be soldered to the little circle pad on the BMS that the other two are touching ?

 

[E-HP]

yes it is functioning properly.

Ok so heres some morew news..

on the bms i habve 3 red wires and 3 black wires. the 3 red wires are all soldered together in a group. The black wires have 2 soldered together that touch a small circle on the BMS and 1 that is a hairline away but is not touching the pad.

these wires are Charge port 1, 2 and the power that goes to the controller.

when i connect my multimeter leads to the red wire group at the BMS and then the group of 2 black charger cables at the BMS I always get a solid 54.6v reading

When I move the black lead to the the the single black wire that would connect to the controller, it briefly reads 48v and then rapidly drops to the mV.

If i connect my controller and then simultaneously touch the black multimeter leads to both the black charger wires and the black controller wire at the BMS, i get a spark and then then the single black controller wire+red wire group reads 54.6v and stays steady.

I am then able to power on my scooter for the first time since this started. But only for 2 seconds before it shuts off and i have to do it again.

Is it possible that this single black wire being so microscopically close to the other 2 is supposed to be soldered to the little circle pad on the BMS that the other two are touching ?

Looking at your other thread as well. I would dump the pack, since you’ve had it overcharged for a while, and it could fail at any time. The BMS seems to be tripped because of that, and your touching the BMS ground input and output is just bypassing the tripped BMS.
Going to the NICU is important, but it’s also important for him to have a father. If he’s a premee then find alternative transportation for the next several weeks.

 

[mattek]

Update:


I cut the power wires that go from the controller to the bms and clamped them in to alligator clips, and then i then clipped those on to the first and last nickel strips in the series (+ and - ) and now the scooter powers up and functions completely normal.

 

[eee291]

You need to be very careful with under/over voltage. I recently killed a small 24v battery that had no BMS, cells are now sitting at 8V.
Fortunately only 25 bucks down the drain

 

[E-HP]

Update:


I cut the power wires that go from the controller to the bms and clamped them in to alligator clips, and then i then clipped those on to the first and last nickel strips in the series (+ and - ) and now the scooter powers up and functions completely normal.

You’ve effectively bypassed the BMS that shut down to protect the battery from further damage or catastrophic failure.
But it looks like you’ve been provided enough information to make the right decision, and in the big picture, it’s only one of thousands of decisions you’ll be relied upon to make in the next 18 years. Good luck, be safe, and I hope your kid gets out of the nicu soon.

 

[docw009]

Without a working BMS, you will run the cells outside their safe limits. They may already be damaged. You're liable to have the pack catch fire.

 

[mattek]

Without a working BMS, you will run the cells outside their safe limits. They may already be damaged. You're liable to have the pack catch fire.

im just saying, at least now there's no question about the issue here.
Can i not just replace the bms?