Daly bms driving me crazy

[Farmgirl0527]

I bought 2 Daly smart bms units, a 150 and a 200 amp 16s. If I charge batteries to about 54 volts my balance is good. Once above this several batteries start going over the protect settings of 3.6 per cell. Yes I balanced them and this also is my second battery set I'm trying to use. So I try a JK BMS and it balances batteries nicely. Up my voltage to 57 volts. Used it for over a week then tried the Daly units again. Same thing happening. Am I doing something wrong or are the Daly units crap. I'm leaning to the latter.

 

[sunshine_eggo]

BMS must be configured for balancing only above 3.40V and only during charge.

If you allow BMS to balance all the time, they will UNDO a top balance.

Batteries that sit dormant or are under-utilized will go out of balance due to even the slightest differences in SoC - as little as 0.1%.

JK has an active balancer with much higher balance current.

 

[Jimmynik1]

I bought 2 Daly smart bms units, a 150 and a 200 amp 16s. If I charge batteries to about 54 volts my balance is good. Once above this several batteries start going over the protect settings of 3.6 per cell. Yes I balanced them and this also is my second battery set I'm trying to use. So I try a JK BMS and it balances batteries nicely. Up my voltage to 57 volts. Used it for over a week then tried the Daly units again. Same thing happening. Am I doing something wrong or are the Daly units crap. I'm leaning to the latter.

I posted a bunch about this in another thread. ( https://diysolarforum.com/threads/daly-bms-will-not-balance.27086/page-3 )
Mine does the same thing. I was hung up on making my pack, also 16s, the highest voltage I possibly could. I was then given some great resources and realized I was fully charged and there was no need to continue trying to force more current into a already charged battery bank.
I went through my charger settings and dialed back the float voltage to 53.6 I think and I've had no issues since. I was essentially overcharging or trying to and the bms stopped me from hurting the bank. 3.6 is a good charge voltage but too high for repeated use.
Now my cells stay balanced with a differential voltage of around .002 to .007. Unless you happen to get a bum bms from the get go I think yours is fine. At 3.4v per cell we're at 3.4x4=13.6x4=99% charge. Its not 100% but its balanced and safer for the batteries. I'd dial back the charge voltage, let it charge then. The bms shouldn't be involved in daily use other than protecting, if its stepping in to cut off voltages the charger is set too high.

 

[Lt.Dan]

I posted a bunch about this in another thread. ( https://diysolarforum.com/threads/daly-bms-will-not-balance.27086/page-3 )
Mine does the same thing. I was hung up on making my pack, also 16s, the highest voltage I possibly could. I was then given some great resources and realized I was fully charged and there was no need to continue trying to force more current into a already charged battery bank.
I went through my charger settings and dialed back the float voltage to 53.6 I think and I've had no issues since. I was essentially overcharging or trying to and the bms stopped me from hurting the bank. 3.6 is a good charge voltage but too high for repeated use.
Now my cells stay balanced with a differential voltage of around .002 to .007. Unless you happen to get a bum bms from the get go I think yours is fine. At 3.4v per cell we're at 3.4x4=13.6x4=99% charge. Its not 100% but its balanced and safer for the batteries. I'd dial back the charge voltage, let it charge then. The bms shouldn't be involved in daily use other than protecting, if its stepping in to cut off voltages the charger is set too high.

I know a lot of people on this forum think like this, but I do disagree. While you are staying at 3.35v, and being safe by never overcharging or hitting HVD, your cells could be drifting further and further apart (In SOC, not Voltage) because they are NEVER balancing, eventually you will get one cell at such a low SOC in the pack, that you will be hitting a LVD in the BMS, and have a reduced battery capacity. I try and drive the voltage as high as it will let me without repeated interference of me trying to manually balance more. My pack enjoys sitting around 56.5v. (3.53v per cell). This way my BMS still has time to do some balancing, and the pack never falls out of balance severly.

YMMV.

 

[Jimmynik1]

I know a lot of people on this forum think like this, but I do disagree. While you are staying at 3.35v, and being safe by never overcharging or hitting HVD, your cells could be drifting further and further apart (In SOC, not Voltage) because they are NEVER balancing, eventually you will get one cell at such a low SOC in the pack, that you will be hitting a LVD in the BMS, and have a reduced battery capacity. I try and drive the voltage as high as it will let me without repeated interference of me trying to manually balance more. My pack enjoys sitting around 56.5v. (3.53v per cell). This way my BMS still has time to do some balancing, and the pack never falls out of balance severly.

YMMV.

If that works for you then good on you, I wish my voltage sat higher. But it just doesn't.
You mentioned batteries diverting farther and farther apart I haven't had mine built for that long but I find that's not the case since I corrected my issue of trying to overcharge them and dialed it back they've been 002 or a little higher since.
I suppose part of it also is most people don't have the capabilities to get their pack to a high enough voltage while keeping it balanced. I only have a little 10 amp benchtop supply which incidentally only puts out 5 amps at such a low voltage. And it doesn't even go higher than 30 volts so I have to bust the pack apart into 8s Banks and bring them up and even then it takes eons even to move it .1 of a volt. I did try that initially before seeking help here when I posted on the other forum I mentioned above. I broke it apart into 8s packs and brought the entire pack up to 3.65 then I disconnected and use the charger for the other pack and in that time the first charged pack dropped to the point where it was then out of balance with the second pack so I put it back together came here got some advice took it and according to the numbers I was given my pack is still 99% charged while still being balanced which I'm happy with.

 

[Jimmynik1]

My pack enjoys sitting around 56.5v. (3.53v per cell).

After my test I started charging it back up with setting the boost and charge voltage a little higher.
It was still charging when I checked it before bed and in the morning it was off and settled at 54.0v. No bms code kicked in which is good but I'm back to a not great balance of .150, not as bad as the initial .2 something. Its weird that I can have a good balance of .002 at 53.4v but a little higher throws it out. I'm not sure how to bring my pack to a higher voltage while keeping it balanced or if I should even try.

 

[sunshine_eggo]

After my test I started charging it back up with setting the boost and charge voltage a little higher.
It was still charging when I checked it before bed and in the morning it was off and settled at 54.0v. No bms code kicked in which is good but I'm back to a not great balance of .150, not as bad as the initial .2 something. Its weird that I can have a good balance of .002 at 53.4v

This is not "balance". This is low voltage delta. The only time the word "balance" has any meaning is when the cell voltages are in the upper leg of the charge curve.

"Balance" means the state of charge of all cells is the same, not the voltage. As has been harped on continuously, voltage is not a reliable way to determine state of charge. The only way you can reliably set all cells to the same SoC is at 2.5V (empty, bottom balance) or 3.65V (top balance). Period.

The resting and operating voltage of LFP is in a VERY narrow range, and it would take nightmarish imbalance for them to look out of whack in the 3.3V range.

I've seen a 0.1% difference in SoC between cells produce results comparable to yours.

The quick fix for you (assuming you have a 30V/10A power supply you used to top balance initially like many folks) is to charge each cell individually to 3.65V. This can be done without breaking down the pack. Once all cells have been topped off, set as follows:

Absorption 55.2V
Float 54.4V

Set BMS to:

Balance only above 3.40V
Only if cell deviation is greater than .02V
Only during charge

 

[Jimmynik1]

This is not "balance". This is low voltage delta. The only time the word "balance" has any meaning is when the cell voltages are in the upper leg of the charge curve.

"Balance" means the state of charge of all cells is the same, not the voltage. As has been harped on continuously, voltage is not a reliable way to determine state of charge. The only way you can reliably set all cells to the same SoC is at 2.5V (empty, bottom balance) or 3.65V (top balance). Period.

The resting and operating voltage of LFP is in a VERY narrow range, and it would take nightmarish imbalance for them to look out of whack in the 3.3V range.

I've seen a 0.1% difference in SoC between cells produce results comparable to yours.

Thanks for the info thanks, appreciate it. Struggling to understand difference between lvd and balance.

The quick fix for you (assuming you have a 30V/10A power supply you used to top balance initially like many folks) is to charge each cell individually to 3.65V. This can be done without breaking down the pack. Once all cells have been topped off, set as follows:

Yes I used a 30/5 and a 30/10 to initially top balance.
I tried that but when one would be good I'd move to another and by the time I had say 8 up to 3.65 the first one would be falling to where it started and then each one after that. It was akin to painting a bridge.
My power supply is advertised as 10A but only puts out 5 at 3.65v. I've seen it go up to 10 at a higher voltage messing around with other stuff but not at that low voltage.

Absorption 55.2V
Float 54.4V

Is absorption the same as boost charge voltage? I'm using an eco worthy 3500 hybrid and absorption isn't a setting but boost is.

Balance only above 3.40V
Only if cell deviation is greater than .02V
Only during charge

Ok so its not supposed to balance while not in charge mode. Makes sense why I never see it toggle over off of charge mode.



Reading others posts that have 16s banks it seems they can drive their banks higher while the cells staying in balance (if that's the appropriate time to use balance). I'm at .002 to .004 while in the mid 53s but any higher I loose that .002 and it goes into the .1 and .2 and bms high cell voltage kicks in when one goes higher then 3.65 stopping my whole charge.

 

[sunshine_eggo]

Thanks for the info thanks, appreciate it. Struggling to understand difference between lvd and balance.

Yes I used a 30/5 and a 30/10 to initially top balance.
I tried that but when one would be good I'd move to another and by the time I had say 8 up to 3.65 the first one would be falling to where it started and then each one after that. It was akin to painting a bridge.

That's normal. LFP voltage settles once a charge current is removed, especially if there's any load at all. This should be done with zero or as little as possible load on the battery.

My power supply is advertised as 10A but only puts out 5 at 3.65v. I've seen it go up to 10 at a higher voltage messing around with other stuff but not at that low voltage.

The most common cause for what you describe is low quality charge leads.

Is absorption the same as boost charge voltage? I'm using an eco worthy 3500 hybrid and absorption isn't a setting but boost is.

Yes. Bulk/Boost/Absorption voltage all describe the same thing in most cases.

Ok so its not supposed to balance while not in charge mode. Makes sense why I never see it toggle over off of charge mode.

If you balance continuously based on voltage during discharge or at rest, you can undo a top balance.

 

[Jimmynik1]

The most common cause for what you describe is low quality charge leads.

Idk its brand new, I've seen it put out 10 when I hook it to a drill or dead car battery and raise voltage just not at this low cell voltage.

That's normal. LFP voltage settles once a charge current is removed, especially if there's any load at all. This should be done with zero or as little as possible load on the battery.

So then how does one do this and keep them up while charging others. I did it with no load just connected to the charger but the charger wasn't charging and no load was on the bank.



Thank you very much.
I added this while you were typing the above.

Reading others posts that have 16s banks it seems they can drive their banks higher while the cells staying in balance (if that's the appropriate time to use balance). I'm at .002 to .004 while in the mid 53s but any higher I loose that .002 and it goes into the .1 and .2 and bms high cell voltage kicks in when one goes higher then 3.65 stopping my whole charge.

Basically should I be content with a 53.5/4 bank at .002 - .004 or strive for higher? And if yes how to keep the .002 - .004 that I loose when I go higher.

 

[sunshine_eggo]

Idk its brand new, I've seen it put out 10 when I hook it to a drill or dead car battery and raise voltage just not at this low cell voltage.

So then how does one do this and keep them up while charging others. I did it with no load just connected to the charger but the charger wasn't charging and no load was on the bank.

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.

Thank you very much.
I added this while you were typing the above.

Reading others posts that have 16s banks it seems they can drive their banks higher while the cells staying in balance (if that's the appropriate time to use balance). I'm at .002 to .004 while in the mid 53s but any higher I loose that .002 and it goes into the .1 and .2 and bms high cell voltage kicks in when one goes higher then 3.65 stopping my whole charge.

Basically should I be content with a 53.5/4 bank at .002 - .004 or strive for higher? And if yes how to keep the .002 - .004 that I loose when I go higher.

I wouldn't be. Without charging to a least 3.4V/cell (54.4V), you can't be certain you're getting anywhere near fully charged. 3.4 gets you to about 95% and 3.45 gets you to about 98%. Both of these charge schemes can add 3-6 hours to the absorption phase of charging.

Again, the only time voltage deviation has any positive meaning is when all cells are in the upper leg of the curve. You're not in it at 53.5V.

 

[Jimmynik1]

Absorption 55.2V
Float 54.4V

Somewhat back to where I was before when I initially sought out advice a couple weeks back here.
I set those voltages and now one or two cells reached high voltage shut off and the BMS stopped the charging. I think I'm at 54.1 right now. With .134 difference or something like that. I can't get higher voltage keeping those numbers closer together because the BMS won't allow it.


Unsure of how to go higher with BMS stopping charging due to one or two cells being at the cutoff

 

[sunshine_eggo]

Somewhat back to where I was before when I initially sought out advice a couple weeks back here.
I set those voltages and now one or two cells reached high voltage shut off and the BMS stopped the charging. I think I'm at 54.1 right now. With .134 difference or something like that. I can't get higher voltage keeping those numbers closer together because the BMS won't allow it.


Unsure of how to go higher with BMS stopping charging due to one or two cells being at the cutoff

The quick fix for you (assuming you have a 30V/10A power supply you used to top balance initially like many folks) is to charge each cell individually to 3.65V. This can be done without breaking down the pack. Once all cells have been topped off, set as follows:

 

[Jimmynik1]

Yea I understand. I did one cell over night to 3.65 and the switched it to another before work. I may have not explained it right before but I'm pretty confident by the time I get to the 7th cell, my first I got up to 3.65 will be in the 3.4s and sequentially up to the one I'm working on. And then I've essentially done nothing as they look the same as when I started.
I got a 5a balancer of amazon that had decent reviews. If it doesn't help I can always return it.

 

[sunshine_eggo]

Yea I understand. I did one cell over night to 3.65 and the switched it to another before work. I may have not explained it right before but I'm pretty confident by the time I get to the 7th cell, my first I got up to 3.65 will be in the 3.4s and sequentially up to the one I'm working on. And then I've essentially done nothing as they look the same as when I started.
I got a 5a balancer of amazon that had decent reviews. If it doesn't help I can always return it.

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.

Again, resting voltage after fully charging matters barely more than nothing for this purpose. If you're discharging the battery, that makes it worse.

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.

Again, once you've finished all, #1 will be lower, but again, THAT DOESN'T MATTER. Discharge the battery, then set charge to 3.55V/cell if you want fast charging or 3.45V/cell if you want slow charging (may enhance cycle life).

Set the BMS to balance only during charge and you should be good from here. If not, you have problems with your cells, your setup, terminal crimps, connections or the BMS itself.

 

[Lt.Dan]

Everybody keeps saying to set it to only balance during charging, but Daly BMS does not have the option to balance all the time. I have tried for almost a year now, to get Daly to add that feature.

 

[Jimmynik1]

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.

Again, resting voltage after fully charging matters barely more than nothing for this purpose. If you're discharging the battery, that makes it worse.

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.

Again, once you've finished all, #1 will be lower, but again, THAT DOESN'T MATTER. Discharge the battery, then set charge to 3.55V/cell if you want fast charging or 3.45V/cell if you want slow charging (may enhance cycle life).

Set the BMS to balance only during charge and you should be good from here. If not, you have problems with your cells, your setup, terminal crimps, connections or the BMS itself.

I appreciate your responses and more so having patience with me as I learn.

I got home from work and ran a heat gun for a little bit while I cleaned up and this is where the pack is at now I left it unplugged so the charger won't kick in.

Would you suggest I plug the charger back in and bring them up to what the charger will take them up to without having any BMS intervention?

 

[sunshine_eggo]

I appreciate your responses and more so having patience with me as I learn.

I got home from work and ran a heat gun for a little bit while I cleaned up and this is where the pack is at now I left it unplugged so the charger won't kick in.

Was this after you had been through all 16 cells twice? If so, charge to 3.55V/cell and see what happens.

 

[Jimmynik1]

Was this after you had been through all 16 cells twice? If so, charge to 3.55V/cell and see what happens.

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.

 

[Lt.Dan]

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.

3.32 to 3.4v is huge in 10 minutes, as that's a very broad range there. But going from 3.4v to 3.5v will be very fast