Daly bms driving me crazy

[Jimmynik1]

3.32 to 3.4v

Good to know I think. Still learning about these batteries.
Idk whats up with my setup. Its not unusable, I did draw 31a dc out of it over 9 hours which came to something 275ah out of an advertised 310ah capacity then whatever room is supposed to be left to not discharge fully I think I was pretty close to getting full capacity out of it.
I cant go cell to cell with my dc supply, even at 10a it takes more than 10 minutes so make a dent let alone get to 3.65.
No

My charger just stopped again at 53.4 which is what I have the charger set to. I picked a random cell and in 10 minutes I went from 3.358 to 3.365. With my supply at 3.65 volts and 10 amps. Is something up with my cells you think or is the DC supply not doing what it should do?

25 minutes after charging its at 3.93
45 minutes after charging it's at 3.50

3.358 to 3.50 in 45 minutes

 

[sunshine_eggo]

No. You wrote earlier about it taking single digit minutes to bring the lower cells to 3.65 that doesn't happen in my case. If I'm doing it right and not disconnecting anything leaving the pack and it's 16s configuration putting the power supply on One battery at 3.65 volts and 10 amps it didn't make a considerable difference in about 10 minutes. I started with the lowest one which is 3.32 or something and after 10 minutes it was about 3.4.

If you want my help, please read my posts and do as I ask. I'll quote where I've already repeated myself:

You don't have to keep them there. Once they've all been charged to 3.65V individually, they are balanced at 100% SoC regardless of voltage. Generally, you do two sweeps - however long it takes on cells 1-16, and then hit them again 1-16, but it typically only takes seconds per cell.

If it takes you a significant amount of time to charge the "low" cells vs. the one that's triggering the cut-off, you have an atrociously imbalanced battery.

Assuming the battery is not being discharging, once you've been through the cells, you go through them all again. Each charge should take single digit minutes to get back to 3.65.

Please let me know when you've charged cells 1-16 twice.

 

[Jimmynik1]

If you want my help, please read my posts and do as I ask. I'll quote where I've already repeated myself:





Please let me know when you've charged cells 1-16 twice.

 

[sunshine_eggo]

Awesome.

Roughly how long did it take on the second pass for each cell?
How does the full pack charging respond now?

 

[Daddy Tanuki]

Awesome.

Roughly how long did it take on the second pass for each cell?
How does the full pack charging respond now?

I think he does not understand the fact that the cells will settle after charging down to the 3.4-3.45 range... that seems to be the learning disconnect.

 

[Jimmynik1]

I think he does not understand the fact that the cells will settle after charging down to the 3.4-3.45 range... that seems to be the learning disconnect.

I understand that cells will settle after being charged or discharged I've never seen a battery that doesn't.
What I didn't get and get now is that although all of my cells were say 3.33 at the same time they were not balanced when I thought they were. It took a while to understand that they could be wildly different states of charges at around the same voltages. They needed to be very close if not the same in SOC to be balanced and I'm hoping now they are.

The first go around with a 10 amp took a while the second go around was really quick. By the time I was done the balance that I bought came so I stuck that on and it seems to be doing its job.

Picture below is where they settled to overnight.

 

[Daddy Tanuki]

Check. Thought the settling issue was confusing you.

 

[sunshine_eggo]

I understand that cells will settle after being charged or discharged I've never seen a battery that doesn't.
What I didn't get and get now is that although all of my cells were say 3.33 at the same time they were not balanced when I thought they were. It took a while to understand that they could be wildly different states of charges at around the same voltages. They needed to be very close if not the same in SOC to be balanced and I'm hoping now they are.

The first go around with a 10 amp took a while the second go around was really quick. By the time I was done the balance that I bought came so I stuck that on and it seems to be doing its job.

That indicates the first charge of each cell got them all at 100% or at least close enough to not matter.

Active balancers are great, but they can hose a top balance if you end up working them much down below 3.4V. They aren't smart enough to know to do it only when charging. Hopefully, their voltage deviation spec is no lower than 10-20mV. If your cells are decent matches for one another, they should maintain balance well.

 

[Jimmynik1]

Check. Thought the settling issue was confusing you.

Initially yea. In the beginning I didn't understand the difference between being "balanced" at say 3.33 and then actually being top balanced at 3.65. So then it was my bms stopping the charge when one cell would hit hvd. But I think I'm decent now. Appreciate it.

 

[Jimmynik1]

That indicates the first charge of each cell got them all at 100% or at least close enough to not matter.

Active balancers are great, but they can hose a top balance if you end up working them much down below 3.4V. They aren't smart enough to know to do it only when charging. Hopefully, their voltage deviation spec is no lower than 10-20mV. If your cells are decent matches for one another, they should maintain balance well.

Awesome.


To not work them below 3.4 I guess I'd just unplug it? There is no on off switch.
If voltage equalization accuracy is the same as deviation spec it's listed as 5mv. What's that mean?

 

[sunshine_eggo]

Awesome.


To not work them below 3.4 I guess I'd just unplug it? There is no on off switch.
If voltage equalization accuracy is the same as deviation spec it's listed as 5mv. What's that mean?

Yeah. It's going to try to balance any time voltages vary by more than .005.

 

[BigDaddyJ]

Great info here! I’m also a newb to this and have built a 16s pack with a Daly BMS and am hitting this same exact issue. One question though. When you indicate that the cells can be charged without taking the pack apart you mean I can connect the charger to one cell at a time and run it I assume. So that wouldn’t push voltage into the whole pack because I’m not connected to the main neg and pos terminals then? Also should I be disconnecting the pack from my inverter/charger while I do this?

 

[sunshine_eggo]

Great info here! I’m also a newb to this and have built a 16s pack with a Daly BMS and am hitting this same exact issue. One question though. When you indicate that the cells can be charged without taking the pack apart you mean I can connect the charger to one cell at a time and run it I assume.

Yes.

So that wouldn’t push voltage into the whole pack because I’m not connected to the main neg and pos terminals then?

Correct.

Also should I be disconnecting the pack from my inverter/charger while I do this?

Not necessarily, but you should avoid loads or charging from other sources.

 

[BigDaddyJ]

Yes.



Correct.



Not necessarily, but you should avoid loads or charging from other sources.

Awesome, thank you very much, I think this is the last piece I need to get my project over the line. This forum has been an incredible source of information thanks to all the folks willing to help. I’ll soon be waving goodbye to the constant power drop outs and fluctuations Georgia Power call electrical service.

 

[Jimmynik1]

Awesome, thank you very much, I think this is the last piece I need to get my project over the line. This forum has been an incredible source of information thanks to all the folks willing to help. I’ll soon be waving goodbye to the constant power drop outs and fluctuations Georgia Power call electrical service.

How you make out?

 

[Jimmynik1]

Active balancers are great, but they can hose a top balance if you end up working them much down below 3.4V.

Pretty sure that happened. My system isn't in use really, I made it to offset a generator if a long term outage occurs. So it just sits on my bench cycling on and off from charging. I noticed the other day checking the app that I hit a high cell alarm with one cell hitting 3.65 while charging while others were at 3.35 +/- when I haven't in a while since I followed your advice and made the pack actually top balanced. So I just did what I did above the first time and ran through the bank with my DC supply bringing them up tp 3.6 once, then again and before I knew it I was back to 3.45s with a .004 diff.

 

[Farmgirl0527]

Well, speed off is an understatement.
My new jk bms is doing something very strange. When,charging 8 of the batteries show cell volts that are higher than the other 8. Very quickly ,one will go into overvolt and shut the system down. If I recongure the string and have the first 8 which showed good, then now show bad. Trying to get the seller to understand is near impossible.
Now for my returned JK,unit. Held at shipping location because no one at store is accepting. I've asked several times why but get no response., Once I get this worked In done with China crap I was impressed with the jk unit until this all began. Now I've been without a system for months.
,

 

[Jimmynik1]

Well, speed off is an understatement.
My new jk bms is doing something very strange. When,charging 8 of the batteries show cell volts that are higher than the other 8. Very quickly ,one will go into overvolt and shut the system down. If I recongure the string and have the first 8 which showed good, then now show bad. Trying to get the seller to understand is near impossible.
Now for my returned JK,unit. Held at shipping location because no one at store is accepting. I've asked several times why but get no response., Once I get this worked In done with China crap I was impressed with the jk unit until this all began. Now I've been without a system for months.
,

Sounds like you made the right first move and returned the old one, I've had no issues with my daly 16s 100a coupled with the 16s balancer off amazon, I forgot the brand around 80 bucks. But after a proper top balance my bank will sit at 56.1 or so with 005 differential.

 

[Daddy Tanuki]

Sounds like you made the right first move and returned the old one, I've had no issues with my daly 16s 100a coupled with the 16s balancer off amazon, I forgot the brand around 80 bucks. But after a proper top balance my bank will sit at 56.1 or so with 005 differential.

The only issues I had with the DALY's were fixed with the new BT dongle as it has a start button to wake it from sleep if you don't bother to set the sleep timer settings. I am running three of the 100/200 16S units and two of the packs stay well balanced at 55.2 with 5 or 6 millivolt differential. the third pack on the other hand did not receive as good of a top balance before commissioning and it shows. I had to shut that pack down, drain it till the lowest cells hit 3.3 and then use light bulb to lower a couple of cells while it sits awaiting spring so that I can pull the pack apart and rebalance them properly. but that's my error not the BMS's.

I was about to give up on DALY and even went as far as to order a chargery to play with but have not had to use it.

 

[BigDaddyJ]

How you make out?

Worked like a champ. Took me about a week for each cell initially. Once I got them all to 3.65 I went back through them to top them up and that went very quickly. I’m now at a delta of .002 across all 16 cells.

I have a charging issue I haven’t figured out yet but I think it with the Daly. My combo inverter/charger is indicating its in charge mode and is set to charge to 58v (same as the setting on the Daly) but the Daly is stopping at 53.1.

I have a JK BMs on hand and I’m going to swap it in when I reconfigure the pack to change its shape. I ended up needing it to be narrower and longer then I have it right now and I’m going to change the box construction as well.

But for now I’m good, version 1.0 is doing what I need it too. I’m using this as a UPS for about half my house. The power where I live can be finicky and we have hours long power outages from time to time and this system gives me about 10 hours of run time for the important stuff; refrigerator, freezer, faking room, bathrooms, entertainment center, home network and internet. I just need to do some tweaking and I’m golden.

Thanks again for the help, it got me over the hump!