Help me troubleshoot this pack please. How are these voltages?

[999zip999]

Remember we are the punks of the punk but thank you for your time

 

[eikido]

Thanks for everything.
Yes i'm from Sweden

 

[john61ct]

Might be best to leave the BMS alone

and use a dedicated balancer unit that will do a better job at that function anyway

https://zhcsolar.com/product/ha02-battery-equalizer

https://tinyurl.com/yx4fn379

Or Chargery BMS16T/BMS16 Pro or BMS24T/BMS24 Pro.

Then can use with multiple packs, and does not interfere with your preferred charging protocol

 

[eikido]

Might be best to leave the BMS alone

and use a dedicated balancer unit that will do a better job at that function anyway

I see.
Since there aren't any 13s balancers, what is your recommendation to balance?
Use something like the IMAX B6 and balance 6 cell parallels at a time?
https://www.skyrc.com/iMAX_B6_Charger

 

[john61ct]

I just posted a bunch of dedicated balancers for you to look at!

Anything over 13S should handle 13S.

Balance **charging** is entirely different. That one is cr^p and only 6S anyway.

Even 12S gets very hard to find 14S crazy expensive.

But yes can be a great approach. To go that way, best to build 6S and 7S packs, charge them separated in an 8S charger like FMA PL8 or iCharger 4010-Duo, then reconnect to get 13S for discharging.

Next pack maybe?

 

[john61ct]

Actually, an 8S charger could do each "half" of your 13S sequentially

just not at the same time, pretty inconvenient.

 

[zeccato]

I'd measure all the 13s while he's charging, to see the highest, or how far they go...

 

[eikido]

Thanks all.
I'm very sorry @john61ct, i missed those balance chargers in the previous post, sorry.
I will try to get one of them.

Here are measurements fully charged.

1: 4.13
2: 4.12
3: 4.11
4: 4.10
5: 4.13
6: 4.12
7: 4.12
8: 4.13
9: 4.13
10: 4.12
11: 4.04
12: 4.12
13: 4.13

I guess 11 doesn't look good?
Largest difference:
4.13-4.04=0.09

Is that too much of a difference?

 

[john61ct]

I'm very sorry @john61ct, i missed those balance chargers in the previous post, sorry

Those aren't "balance chargers".

They are "balancers" or sometimes "not protective BMS". Some do not require working with a charge source at all, they shuttle excess energy from the high cells to the low ones until everything is even, and work at whatever SoC point you prefer.

I would learn more about them maybe start a thread asking for feedback from any members that have owned them, before actually purchasing any.

And yes, most target getting cells within 3-5 mV, nearly 0.1V is a fair bit.

Could try bringing it up manually a bit with a suitable charge source, see how you go in the meantime.

Maybe even try a cheaper adjustable BMS just hook it up as needed while charging for balancing purposes.

Is the pack of a type where atomizing the cells to deal with them isolated would be a pain?

 

[eikido]

I'm very sorry @john61ct, i missed those balance chargers in the previous post, sorry

Those aren't "balance chargers".

They are "balancers" or sometimes "not protective BMS". Some do not require working with a charge source at all, they shuttle excess energy from the high cells to the low ones until everything is even, and work at whatever SoC point you prefer.

I would learn more about them maybe start a thread asking for feedback from any members that have owned them, before actually purchasing any.

And yes, most target getting cells within 3-5 mV, nearly 0.1V is a fair bit.

Could try bringing it up manually a bit with a suitable charge source, see how you go in the meantime.

Maybe even try a cheaper adjustable BMS just hook it up as needed while charging for balancing purposes.

Is the pack of a type where atomizing the cells to deal with them isolated would be a pain?

I see. I will create a new thread about those balancers. Thanks for that, i start to understand how they work and they are really interesting!

I will charge cell 11 manually to balance it with the other cells.

And for this question.

Is the pack of a type where atomizing the cells to deal with them isolated would be a pain?

Yes it is:\

 

[eikido]

After i fully charged the pack (cell 11=4.04v) and waited one day, cell 11 dropped to 4.00v (compared to highest cell voltage of 4.13v).
So i balanced cell 11 to 4.13v and after one day, it dropped to 4.06v.
The other cells have held their voltage for two days (one cell dropped 0.02v which should be ok).

Does this say anything or is this normal?

 

[john61ct]

Is that a cell or a group?

Yes indicates weakness, IMO needs atomized load testing likely replacement

unless you're willing to let that cell / group capacity dictate the (much reduced) range of the whole pack

 

[eikido]

Is that a cell or a group?

Yes indicates weakness, IMO needs atomized load testing likely replacement

unless you're willing to let that cell / group capacity dictate the (much reduced) range of the whole pack

It's a group. It's 6P.
I will disassemble the whole pack, find the bad cell and rebuild it to a 5P.
I will use a liitokala lii-500s to find the bad cell.

Thanks.

 

[john61ct]

May be more than one.

Ideally test them all discard the worst, try to get groups matched as close as possible.

An ESR tester would also be good.

Interesting cheap cap tester that, has it been well tested as accurate, as compared to the ZKETECHs or Maynuo?

 

[fechter]

After i fully charged the pack (cell 11=4.04v) and waited one day, cell 11 dropped to 4.00v (compared to highest cell voltage of 4.13v).
So i balanced cell 11 to 4.13v and after one day, it dropped to 4.06v.
The other cells have held their voltage for two days (one cell dropped 0.02v which should be ok).

Does this say anything or is this normal?

You might want to repeat the test with the BMS unplugged. It's possible the BMS has a stuck-on balancing shunt. If you have good access to the BMS, you can also measure the voltage across all the balancing load resistors. They should be all zero.

 

[eikido]

After i fully charged the pack (cell 11=4.04v) and waited one day, cell 11 dropped to 4.00v (compared to highest cell voltage of 4.13v).
So i balanced cell 11 to 4.13v and after one day, it dropped to 4.06v.
The other cells have held their voltage for two days (one cell dropped 0.02v which should be ok).

Does this say anything or is this normal?

You might want to repeat the test with the BMS unplugged. It's possible the BMS has a stuck-on balancing shunt. If you have good access to the BMS, you can also measure the voltage across all the balancing load resistors. They should be all zero.

The bms does not have balancing function. Should I be worried about that? Are they really necessary?

 

[zeccato]

Does the battery do less miles (km) than before?

 

[john61ct]

No protective-only BMS is fine

but every pack will likely need balancing eventually somehow.

It is true that any BMS can fail and wreck (a subset of) the pack (why some call them Battery Murder Systems)

or not if you catch the fault early

 

[eikido]

Does the battery do less miles (km) than before?

Brand new. Charged full one time. I do have warranty but it's going to cost more to get it shipped back. Plus I have all equipment to rebuild it. K weld, pure nickel, kapton tape etc. Plus it's fun and educational so I appreciate all your guys help. I do read a lot and check YouTube vids.

It works fine down to 50% capacity. Then it turns off when loaded, even a little load, and won't turn on unless it is plugged into the charger very briefly.

 

[zeccato]

I think that after 3 or 4 unloaded charges it will normalize, if charged up to at least 4v is fine, the difference is minimal.
In my opinion, I wouldn't do anything,
just sometimes the balance.
You use it for ebike?

 

[eikido]

I think that after 3 or 4 unloaded charges it will normalize, if charged up to at least 4v is fine, the difference is minimal.
In my opinion, I wouldn't do anything,
just sometimes the balance.
You use it for ebike?

It's for a 500w electric scooter. Burst >1000w.

 

[999zip999]

I would put some sense wires on it for ez monitoring and balanceing with a cellog and I use una6 hru the sense wire charger. 5s 5s and 3s.

 

[eikido]

Cell group 11 confirmed bad.
I'm lucky and managed to borrow a DC electronic loader.
When i reach ~3.488v then cell group 11 starts to get too much out of balance from the rest cell groups. Like 0.16-0.20v below the strongest cell group and the BMS shuts off.
Everything is fine from full charge (4.13v) down to ~3.5v and cell group 11 still stays well within tolerance.
I will try to rebuild this pack.

I'm trying to find BMS specs when the BMS's shuts off when a group gets too much out of tolerance.
Does anyone know a rough number? 0.15v?

 

[john61ct]

I would put some sense wires on it for ez monitoring and balanceing with a cellog and I use una6 hru the sense wire charger. 5s 5s and 3s.

What is a "cellog" to you these days?

Been many years since the actual CellLogs were discontinued, afaict completely unavailable for a long time.

Also what are reliable suppliers of the UNRC chargers, ideally North American?

 

[john61ct]

Everything is fine from full charge (4.13v) down to ~3.5v and cell group 11 still stays well within tolerance.
I will try to rebuild this pack.

I'm trying to find BMS specs when the BMS's shuts off when a group gets too much out of tolerance.
Does anyone know a rough number? 0.15v?

Really depends on the specific model BMS, they each differ.

Ideal is, that parameter is adjustable, along with the other more common ones.

Consider just getting a new pack, and use that one for only shorter trips, as is?

Likely not much useful range below 3.5Vpc anyway.