Problems?

Oldspot

100 mW
Joined
Nov 30, 2021
Messages
47
Battery from China 72v Li ion 150Ah.200amp BMS
10 amp smart charger
QS 138 90 4000w Votul em200sp
Turned up after 4 months
Put on charge, now I am testing under load.
I have had cut out problems but starts again once stationary.
Came to a sudden stop no warning coulomb counter and battery completely off.
Charged again after 10 mins pulling about 25amps cut out coulomb reading 0
E151C496-56C5-45D1-BF58-A7C5CD46E44A.jpeg
So now I have a zero level, charged again, probably cells not balanced
Took 24 hrs of charging (mainly with the green indicator light on) but slowly creeping up from 0%
So now charger has stopped.
9AE06DFE-97B7-456E-AC70-FAD1D69EA29B.jpeg
If I have a zero should it not go to 100% is it balanced, I have contacted the battery company but they are asking silly questions
Where do I start or test
 
what did you program as the high and low cutoff voltage for your coulombmeter? For a 72 volt battery it should be 84 volts. On the LCD screen it reads 83.6 volts (short of the 84 volts) . Coulombmeter won't reset to 100 percent unless it sees the max high cutoff voltage that you set.
If the charger is only charging to 83.6 volts, you might want to reset the coulombmeter high cutoff to 83.6 volts and it will go to 100 percent when that voltage is reached. The low voltage cutoff should be 56 volts. And your AH should be whatever the battery is rated.
 
Thanks for reply, yes programmed correctly this morning it got to 84.1 and set to 100%
I could also have pushed the top button for a while and set it.
So great, better have a test drive, went 10ft battery cut out coulomb went to 0v then faded.
C36E4F9A-47D1-4B29-B9AE-01BA85C2F546.jpeg
I of course get a undervoltage error,
Now I’m getting a hall fault 000080.
I suppose my question is it the battery/ controller/ wiring
Last week I probably drove it for an hour (slowly) it seemed to me battery related, new battery not balance.
Now I’m lost!
 
When power completely fails it means your BMS is shutting off for some reason. If it happens under higher loads, it could be a few things.

If the BMS can sense current, and has a current limit, you might be exceeding that. A problem resulting in hall fault on a controller could cause a controller to draw much more current than it should (either continuously or in spikes, and the spikes may not show up on your meters if theyr'e short enough).

If there is a cell group with a problematic cell or interconnect, it may charge and balance normally, but when placed under load for discharge it may have enough voltage drop to trigger BMS LVC shutdown.
 
are you sure its a 150ah 72 volt battery? When you first charged it up, the coulombmeter showed it put in 48.5 ah's into it. I think that part of the coulombmeter was correct, it might be a 50ah battery.

There might be a cell that is bad and drops too much voltage when you put a load on it. The only way to find the bad cell is to check the voltage on every cell. If the battery has a balance connector where you can check cell voltage it be easy to do with a voltmeter.

Let the mfg know about the errors you are getting, maybe they can advise you what else to check next. Do you have a picture of the battery.
.
 
Thanks, I am so appreciative to get a reply,
The battery
0751910E-9A0B-44CD-BE65-EA19542FCC64.png
It was a long time in transit, I have been in contact with the manufacturer
I think I am a little closer, the battery with charger connected reads 84v
I unplugged the Anderson so just battery and charger
Last week I ran it for a bit (with cut outs) but now reads 84v, disconnect the charger after 2 mins nothing
Sinks rapidly down to about 2v
Can I test anything?
This is my first build so I thought buying a battery would make it simpler
What should I expect the supplier to do?
I live in the uk should I find a lithium battery “expert” to look at it or do I rip it apart?!
 
That charger is a joke.. probably like a 5A charger for a 150Ah battery? That would take 30 hours to charge :warn:


You need to show us what's inside. :|

Found a similar listing:
https://www.aliexpress.com/item/1005004165305993.html
30kg for 10kwh? It would need to weigh about 50-60kg, in my experience.
A tesla module @5.4kwh weighs 25kg.
 
You said you paid extra for the 200A bms, so it might have bluetooth. if the bms has bluetooth, you don't have to open it up, the bms should report each of the cells voltage. If one of the cells is low, you will find the problem quickly.
 
Oldspot said:
The battery
0751910E-9A0B-44CD-BE65-EA19542FCC64.png

Is that an SB50 Anderson plug? If so, that battery almost certainly isn't physically large enough to be 72v 150Ah (10.8kwh). My 2kwh 52v 40Ah EIG pack (14s 2p of EIG C020 20Ah cells) looks a bit more than half that size (relative to an SB50), and weighs something between 16-18kg (don't remember exactly).
IMG_4063.JPG


If it's really a 10.8kwh pack, then depending on what cells it's made of and how heavy the casing is, I'd expect it to weigh at least four times and probably five times, what my 2kwh pack does, and be about four to five times it's physical size. If it doesnt' weigh at least, oh, 50-60kg (and probably more, because of the casing if nothing else), it's probably not what it says it is.



Last week I ran it for a bit (with cut outs) but now reads 84v, disconnect the charger after 2 mins nothing
Sinks rapidly down to about 2v
When that happens, it means the BMS has shut off it's output to protect the battery; the voltage you see is a "ghost" voltage, any load on it would drop it to 0v.

Can I test anything?
Unless the BMS has bluetooth or some other wireless connection that you can access individual cell group voltage, then to see what is happening you would need to open it up and use a multimeter to test individual cell group voltages.

Other tests can be done with that access, while the battery is under the same conditions that makes it shut off, that might tell you even more.

Keep in mind that opening it may void any warranty it might have. I'd check with the seller first to see what they are willing to do. If they are unwilling to do anything, then I would check with paypal or your bank or however you paid for it, to see if they are willing to do something.
 
Thanks, the package was 62kg
480x310x290 so big lump
I will wait on the supplier, then maybe take apart.
 
So the supplier has told me to open up and test.
Would it be any help if I posted pics on here of the inside, I have looked through lots of threads can anyone point me in the right direction, thanks
 
Unless we see the inside of the pack no one is going to able to help you properly.
You need a voltmeter of course.

I would measure the individual cells via the BMS connector.
If the cell tabs are exposed or easy to get to I'd also measure the voltage directly just make sure, it could be just a broken wire or battery connection.

Hillhater said:
£1,800 is a big gamble to be breaking any warranty terms that you may not have seen .
I would ask for a replacement or refund
I trust you used secure payment, Paypal, credit card, etc
You know they are gonna ask that he ships the Battery back.
If the seller claims that you voided the warranty just show Aliexpress support the message history.
 
Ok so I was told to open it
2266C14E-3376-4CDA-9BB8-F8DE42BEC793.jpeg
First thing is that volt meter says 44.5
35598265-EEFA-4148-850F-DEB35E18629F.jpeg
Right so still couldn’t see much
FD9C1DCE-7D02-4EBC-8DFC-26B803CABC2C.jpeg
Now I presume I can test cells
 
To keep everyone in the loop (because this community will be the only way I may see this working).
D3C1E09D-FE8B-4D15-B6B0-0DD7E335DA42.png
 
Just pry at the foam pads enough to expose the cells, but I'm guessing these cells have one tab on the top and the other on the bottom.
 
Oldspot said:
First thing is that volt meter says 44.5
35598265-EEFA-4148-850F-DEB35E18629F.jpeg
When measuring what specific points?

If you can also take off the other side panel opposite the one you have so far, it should expose the tabs on the other end of the cells, and possibly the BMS as well (if it's inside that enclosure with the cells).

Then you can measure voltage of each cell (or group) with the meter probes, one meter lead at each end of each cell that you can see. I would make a list starting at the most negative cell first, which is the cell group with the fat wire (probably black) going to the BMS board. Measuring every cell you will probably have 40 voltages (see below), each pair of which will probably be identical, but potentially differetn (if there is a balance problem) between each pair.

It's not completely clear how they have the cells grouped/connected together, but I would guess they are 2p; it looks like 20 cells in each stack, and 40 cells in 2p would give a 20s2p pack. Each black block (foam?) probably covers the interconnect of four cells--two positive terminals in parallel connected to two negative terminals in parallel, with a balance / sense wire to the BMS from each of these connnections.

The group ends should then be shifted at the other end of the box so they overlap the points that on this side are between the black blocks.

If that's the case, you should get the same voltage across each cell in each pair, measured across the ends of the cells.


After you have measured at the cells themselves, then if you can also access the BMS's connector plug where the balance/sense wires go, try to measure each pair of pins, starting at the most negative end, at the actual solder joints on the BMS board itself. That will test if the wires are connected and working correctly, all the way from cells to BMS. If they are, all the voltags should be identical to the ones read off the cells themselves.



Some notes below:

Right so still couldn’t see much
FD9C1DCE-7D02-4EBC-8DFC-26B803CABC2C.jpeg
Wow. Pardon my phrasing, but that's pretty crappy for a company-built battery. :( (wouldn't be bad for a home-built pack, but that's not what it is)

About a third of that volume is torn up foam (?) padding, not cells. Another large amount is just air. I doubt even half the volume of the pack is cells.

Thanks, the package was 62kg
480x310x290 so big lump
Ok, so I looked up the cell size for my 2kwh pack, and it calculates out to be
237x137x252mm
which gives a volume of 8182188mm cubed

I'm going to guesstimate that you have maybe 300mm at most of that 480mm being cells, and maybe 250mm of the 310mm being cels, and maybe 250mm of the 290mm being cells, making the actual pack size something like
300x250x250mm
which gives a volume of 18750000mm cubed, which is only 2.3x that of my pack's cells. If they are similar Wh per volume cells, then that is about 2.3 x 2kwh = 4.6kwh. (less than half of the claimed 10kwh).

If there are 40 cells, then to be a 72v 150Ah pack, at 20s 2p, each cell would have to be a 75Ah cell. Size-wise, that seems unlikely.

If this is true, then the cells probably also can't supply the current the pack is rated for, aside from the capacity, so they probably sag in voltage significantly under higher loads, and may trigger the BMS shutoff at those times.

Further, the cells would be being used harder (probably a lot harder) than they are designed to be, so they are aging faster and becoming even less capable.

It would be harder and harder for the BMS to rebalance the pack during charging, and take longer and longer for this to happen. When it gets really bad it could take many days just sitting on the charger to rebalance.



EDIT: found a post of mine
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1255590&hilit=scale+weigh%2A#p1255590
that states the 14s2p (28 cell) pack weighs about 35lbs, rounding up. That's about 16kg for 2kwh (it has brass busbars that are probably a couple pounds of that, but there is no outer pack casing). To get a 10kwh pack of these, I'd need 5 times that weight, or about 80kg....
 
Great help thanks
So I’ve been digging around removing foam
Found the BMS
C6D63D1C-6D28-4F6D-B6C1-8851E74EBE5A.jpeg
Should I remove the plate to get to the wires?
I will post readings when I get them
I totally agree that the build is amateurish, this is my noob build and thought buying a battery would be a quicker way to get going😭
 
The pouches are 300mm long without the tabs, 100mm deep and 10mm thick
There are two packs of 20
 
you have to pull on the wires straight back to get the plugs out.
The light could be an indicator for balancing.
 
Oldspot said:
There is a blue flashing light on the circuit board is this normal?

Probably. It could indicate balancing as eee291 notes, or even just a "heartbeat" indicating the BMS has not crashed and is still operating normally.

You shouldn't need to take the cover off the BMS. If you can't reach the BMS connector without doing that, then just measure at the connector where the wires go into the connector; you might have to use a pointy pin or needle to get in there if there's no exposed metal contact at the back.

If possible I would leave the plugs plugged in and not pull them out, because some BMSs are sensitive to the order of connecting the wires, and don't like having the balance plugs removed. Since we don't know anything about this BMS, it's "safer" to leave it in the state it's already in.

If you do need to unplug them, don't pull on the wires to do it, use something insulated (in case you slip) to gently pull the plastic connector out of the plastic shell, at the edge of the plastic connector. Pulling on the actual wires, especially if they are poorly crimped, could cause a problem where there wasnt' one before.

But before you do any of that:


Looks like a JBD BMS, probably the same series as the one here
https://www.aliexpress.com/item/3256802464217319.html
which if it is that, has a BT app you can download to access it's data, making testing much easier. This site is an archive
https://wnsnty.xyz/resource/xiaoxiang
if you can't access it anywhere else.




Oldspot said:
The pouches are 300mm long without the tabs, 100mm deep and 10mm thick
There are two packs of 20

So roughly 300x200x200 for actual cell volume, so even less than I guessed. :(

It's interesting that it uses a contactor; this means there are probably no FETs on the board itself, and instead it uses a relay driver to switch the contactor on / off for protection.
 
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