Have you ever come across dangerous ebike batteries with faulty bms's or extra functions that causes the error?

[leffex]

Have you ever come across dangerous ebike batteries with faulty bms's or extra functions that causes the error?

and did you solve it?

Like if the problem was with the cells, the bms or extra functional items like a usb unit, light unit or battery level indicator unit being the culprit of the problem?

I came across it recently and doing what I can to find out the reason WHY it occurred. When I solve it I will post an update and updates as I go forward in my investigation.

The prime suspects as of now is the bms but there is also a draining unit caring for the indicator and a rear light that drains via positive battery and a connection to the bms p- (power minus) which gives out about 8 volts when bms is switched off.

Suspects are as follow:
BMS. Replaced awaiting confirmation.
Light unit on at standby. To be tested next.
Indicator unit draining when off. Not yet tested.

The problem will only occur possibly when the battery is at the low point of 0% SOC and as such will only fail until that event occurs which it will finally but at different times on different batteries. (Why it occurs is that the drain starts at leven when the cells differ alot in voltage and drains fast even if the level of drain or ghost drain is low it will kill cells and cell groups quickly which it can't at higher level of % SOC. )

 

[999zip999]

What battery pack can you tell us where you got it a link a picture the brand little more info.
1. Do you have a multimeter ?
2. Can you easily open up the battery pack ?

 

[leffex]

Yes. Yes.

A normal 10s4p kind of pack. Configured 3 x 3 + 1. = = = _

Build in China. Imported. I don't have exact information, sorry.

When I did a re-cell of a pack it charged using the said BMS or of the same batch it charged up the new cells to 4.3 for the first 5 rows and 4,08 at the last 5 rows. This is kind of problem number TWO. Very weird occurrence so I'm asking to find out if anyone else is finding out something similar so that we can fight it with knowledge. I'm stunned and need to figure this one out or I'm stuck and won't continue as its a very big deal and a safety risk. It is true I could go around it and remove the extras.

Problem number 1.

Cells drain from something making the pack unusable and then allows some cells to charge. One cell group was way high when I checked before I wrote the post and as such means the BMS didn't work as it is supposed to do or whatever it is supposed to do or configured wrong.

Problem number 2.
As I used the old BMS from another pack of the same kind with new cells it charged up some of the cell groups to 4,3 whilst leaving the other half at lower levels. Only thing from a normal build would be heat gun glue to keep those cells together. I've seen in the past some cells being affected by this and by "ONE" discharge also and then become islands of self-discharge but the cells I used are high grade and high brand company. Also bought from reputable seller so no fakes. If the cells are "pure" the problem lies with what's connected to them.

The truth just takes on its sandals when the lie has travelled half around the earth.

May the force be with us

 

[docw009]

When I did a re-cell of a pack it charged using the said BMS or of the same batch it charged up the new cells to 4.3 for the first 5 rows and 4,08 at the last 5 rows.

How precise is the voltmeter? A good BMS cuts off charge at 4.20 volts, so the 4.3 shouldn't occur. Were all 40 cells new or just half of them? If the voltage is accurate, you have to blame the BMS

Cells drain from something making the pack unusable and then allows some cells to charge. One cell group was way high when I checked before I wrote the post and as such means the BMS didn't work as it is supposed to do or whatever it is supposed to do or configured wrong.

Are you saying that the ten groups were highly unbalanced? Like one group a half volt or more higher than the rest? This happens on old batteries, but not often with high quality cells, It's not a BMS issue if cell groups aren't consistent.

I don't believe any of my purchased batteries have balance circuits. When I put in a new BMS, I do use a balance BMS, but have learned after checking that some don't balance very well. That's how it goes with small time chinese electronics. Some one designs a circuit. Another guy copies it w/o understanding how it works. The marketplace fills up with cheap junk.

 

[amberwolf]

When I did a re-cell of a pack it charged using the said BMS or of the same batch it charged up the new cells to 4.3 for the first 5 rows and 4,08 at the last 5 rows.

That indicates the cells are not matched, so they are different capacities and resistances.

If you use matched cells, then they will all be the same state of charge and the same voltage at the same time.

If you have to depend on the BMS to balance brand new cells, the problems are only going to get worse as time goes on, and it's not a very good repair.


Alternately if you started with matched identical cells, all at the same SoC, and just letting them sit connected to a BMS causes them to change voltage (when they did not while not connected to it), it means the BMS is damaged or defective and is draining whichever cells are lower in voltage (or draining them all and just draining those faster).

 

[99t4]

Some one designs a circuit. Another guy copies it w/o understanding how it works. The marketplace fills up with cheap junk.

The sad truth. A good example: The Grintech TA v.1, that Grin discontinued many years ago because its design is inherently weak, substandard, and incapable. Has been picked up and supplied far and wide by countless vendors to the extent that now it appears to be the TA go-to "standard" that a simple web search comes up with when shopping for a TA.

 

[leffex]

Problem 1. Battery was sitting at low voltage and most of the cells was low and one was 4,4v. I drained it down and recycled it.

Problem 2.
Battery that was re-celled with new cells did at its first charge, charge the first 5 rows of cell groups to 4,3v and the last 5 groups to 4,08v. (cells where glued together with a hot glue gun)

Very odd

I can understand that a bms can fail but bad design from start if it can't do the work it is supposed to doesn't help anyone.

BMS, please:
Don't charge cells higher than 4,2 volt
Don't charge if a cell is way below under voltage
Don't discharge if cell are lower than low voltage settings in bms

I would like to figure this one out. Of course a new higher quality bms can do the job with a cost of 5-15$ in comparisson to the cheapest I guess at 0,5-5$.

 

[DaLanMan]

There is a decision tree in people heads that confuses me.

Ya look at battery prices, see between 2 and 9 bucks a unit.

Then you spend 100-300 bucks on cels.

Then you think "gee, that BMS is gonna be like.. 40 bucks.. Maybe I should get this never heard of before unit that has some chinese characters on it, a little engrish on the back and no diagram.. Yeah, lets save 2 pizza's from the cheap place on the unit that will keep me from having a potential lithium fire just below my knobbly bits....

I even chased down an active bms with remote monitoring for the 4s2p Sodium batteries.. why? because my kid is in a room something like 4 feet from my desk (other side of the wall) and I like having a kid that is not over cooked and can do cool stuff like... breath...

 

[leffex]

There is a decision tree in people heads that confuses me.

Ya look at battery prices, see between 2 and 9 bucks a unit.

Then you spend 100-300 bucks on cels.

Then you think "gee, that BMS is gonna be like.. 40 bucks.. Maybe I should get this never heard of before unit that has some chinese characters on it, a little engrish on the back and no diagram.. Yeah, lets save 2 pizza's from the cheap place on the unit that will keep me from having a potential lithium fire just below my knobbly bits....

I even chased down an active bms with remote monitoring for the 4s2p Sodium batteries.. why? because my kid is in a room something like 4 feet from my desk (other side of the wall) and I like having a kid that is not over cooked and can do cool stuff like... breath...

Yes, I see your point.

I just realized I can test bms s. I can make some mockup batteries and check if they work for the safety items I like them to have.

Problem solved in one sense for my battery builds or the solution is but not the question why it happend or what part of it that has broken, malfunctioned or whatever

 

[DaLanMan]

Or you can do it the way I did ... I decided if I am gonna dink with electric vehicles I need to address the big ole elephaunt in the room, First bike someone offered me was a Miclon something something... it is actually in the boneyard still, I didn't want it and he left it... :: it was originally iirc a 500$ish bike from Wally world. It had it's battery stolen, Miclon wanted I think it was like 350 bucks for a new one. It was a few years old... and there was a NIB unit on a web-store for 150 bucks...

I figured with my sons love of zoomies, I better figure out the battery thing. So I looked around for a problem and came up with a solution that justified me spending money on batteries I had no real use for. I picked up broken battery packs and gutted them, started building little transportable bats for the mass of homeless people (started with a school mate of my sons who was hanging out on our porch where we have a table and chairs and doing homework.. not for the table, he needed the light.)

I have produced over a hundred of those and it has evolved and there are other planners and funders etc involved. But I have an entire segment of shelving (the wife is a bloody saint) currently in the laundry room because it has the best ventilation and a good place to chuck the bucket of sand if it ever grows a burning battery unit...

I have seen some truly hinky shit out of "name brand" vendors. (usually the ones In the bikes are assembled ok, it is the after-market replacements that appear to have been assembled by a blind necrotic monkey) and I was off. digging into things on the never ending quest to vanish the magic smoke.

Somewhere in all that I got on a few lists and get offered sample materials now, they are all very confused when i will accept discounts but TANSTAFL I don't accept free merch.

I am getting to the point where I am comfortable enough I don't think I am gonna burn the house down. I am not comfortable enough to call what I am doing a professional thing. I am an avid hobbyist, that will assemble, stuff it in the slot whatever, but I am not re-selling anything (see, I did learn something in business school) I will charge the living crud out of anything the falls into fabrication services though, That I have professional level skills at... The sparky stuff.. still getting my head around it, and as far as the mechanics of bikes... pff, been dinking with these things since I got my first Huffy. and there are folks here who lose more info on the subject when they sneeze than I have as of yet to acquire. I am just glad they are kind enough to answer my silly questions.

There ya go. Sunday morning Wisdom. My .02 may require you go for change.

 

[leffex]

Yeah. I just hit the jackpot but its too soon to say "Hurray". Whatever I'll have the inventory for the year if it goes well.

I agree with you that you can spot the differences when you have opened a few of one kind. They even have small differences within themselves from year to year sometimes like a fuse was removed and another one was added. What are they doing?

It is true one can ignore the WHY and just go forward but I need it to up my level and also add some shared information that may come in handy for the humanity. For our kind or we'll end up burning down "the place".

 

[amberwolf]

In my experience opening and poking around for curiosity, and sometimes repairing, the many different kinds of electrical and mechanical devices over my life that I have run across:

--if a part can be left out and the device still works well enough to be sold to an end user, preferably without failing before the warranty period is over, it's not going to be in there.

--if the failure rate without the part is acceptable, it won't be in there.

--if the failure rate is too high without the part, but a crappier part can be used and still be in limits, that's what will be in there.

--if something happens that cost the manufacturer significant money in some way, especially a safety thing, a part may be added back in to keep from costing them more than the parts in all those units did.

--if a manufacturer is making batches of devices for some other company, each batch is likely to have differences in the parts used or even which ones got installed vs left out, either because the mfr screwed up, didn't care, whatever, or because the company changed what they were willing to pay for them, etc.

--if it's a really cheap thing, or a clone of a thing or worse a clone of....a clone of a thing, and there's not much chance the end users can make the manufacturer deal with it, then if a part can be left out or substituted with a crappier one and the device wont' catch fire, explode, or turn into powder before the end user opens the box it comes in, it's not going to be in there, even if it removes functionality required to either meet it's advertising, or even to do anything at all in some cases. (aliexpress sellers, etc, I'm looking at you)


There *are* brands and stuff that don't do as much of any of these things as others do...but even the really big companies will not spend any money they don't *have to* on something the end-user is paying for (even if they waste huge amounts of money in other ways).



It doesn't matter all that much for most pieces of technology, but for batteries, or devices with them built in, it makes a huge difference to safety.

The problem is that making more money is *always* more important to any company than any other thing, no matter what that company says or even believes in--if they don't make more money, they won't exist, or not for long.

If they are a conglomerate of different types of companies, they *could* route money from high-profit low-safety-risk parts of the business to the ones that are low-profit high-safety-risk-products, but I don't imagine there are many, if any, that would do that--because it means the people at the top don't make as much money, and they're not going to let any of it go if they can help it.

If they have investors then the investors may have enough control to force saving a penny over a life.

 

[leffex]

I have only seen one part that worked with a lost part in my life regarding to electronics. A cap 16v was lose when my bro received a motherboard. The function wasn't one of the main and maybe an add-on for something but it worked without problems.

I would say. Yes it is important for a company to go around and make money regarding to those who do because there are companies that never goes around but exists through other means. The question here is however if it is ignorance or an understanding that this 1 cent saving will ruin their company one day if they sell critical components that may affect humans in any such way. As you described a safe product is the main thing that makes the company go around and to kill it by making it worse is not logically smart to do as long as you don't know you´re doing it.

 

[leffex]

Battery problem 1 seems to be around the bms as it may allow charge during odd voltages across the cell groups.

High level seems work but not even on this bms of a guy

I have taken the bms into custody. No walking outa here. hehe