I like that and will give it a try... Bottom line, please don't buy LFP on price and don't buy bottom of the barrel junk...
Daly BMS Will Not Balance
- Thread starter Sabre36
- Start date
Some more Daly BMS info:
1- I discharged the battery by about 10% then set the balance voltage to initiate at 3.35V and the cell differential initiation to 0.001V. I then set the power supply to 2.5A (at anything below this, the balancing turns off). The current threshold for balance initiation is not adjustable in the Daly BMS. I then let it charge and the balance indicator light came came on when 3.35VPC and a differential of 0.010V was attained (not the 0.001V it was set for).. This was a good start, or so I thought.
2- Unfortunately the balance indicator then turned off after approx 11 seconds. Repeat, repeat, repeat. So, you need a minimum current flowing into the battery of about 2.5A and even when everything is set to balance, and initiate this at 3.35VPC & a 0.001V imbalance, the balancing is not consistent nor is it continuous. Balancing "takes a break" approx every 10 seconds to 30 seconds (not at all consistent). 10-30 Seconds ON, 10-30 Seconds OFF, repeat, repeat, repeat. The longest duration I have measured balancing remaining ON is 59 seconds, but again, not consistent and no rhyme or reason as to why it is an ON/OFF behavior? It is typicall ON/OFF between 10 & 30 seconds.....?
3- I tried to re-program the zero amperage calibration and it will not stick. The minute you go back into the app, after programming the preferences, the change is wiped out. Thus no way I have found to override the 2 - 2.5A balance threshold for current (this also is not consistent).
4- This morning, at approx 14.25V (manufacturer recommended charge voltage 14.4V), after charging at 2.5A, the SoC was way off reading 76% SoC. This was with 14.25V at the terminals and 0.00A flowing into the battery (14.25V is a full battery and the Charge FETs were on and the battery accepting 0.00A. The following cell voltages were observed.
3.463V
3.687V
3.389V
3.706V
14.245V / Pack
5- I am back at it now with a delta voltage of 0.176V and balancing set to initiate at 3.32V and a 0.001V cell to cell differential, with 2.89A flowing into the cells. Balancing won't initiate at all. This Daly BMS seems to have a mind of its own? Settings changes seem to be a "feel good" measure only. By the settings and amperage this BMS should be balancing, based on the accepted settings (yes, the BMS has saved them) and it's not. It is the job of a BMS to balance cells.
This Daly BMS is the biggest cluster I've yet to see in any BMS. I've been doing custom built LiFePO4 since 2008 so not at all green at this. No matter what I have tried, this Daly BMS cannot and will not balance these 100Ah cells.
I am hoping someone has the answer because this is ridiculous, especially if this is how it is designed to operate. Oh, and apparently every-time you reset/re-program the app the cycle counter goes back to 0.......
How on Earth does Will rate this as a good BMS?
1- I discharged the battery by about 10% then set the balance voltage to initiate at 3.35V and the cell differential initiation to 0.001V. I then set the power supply to 2.5A (at anything below this, the balancing turns off). The current threshold for balance initiation is not adjustable in the Daly BMS. I then let it charge and the balance indicator light came came on when 3.35VPC and a differential of 0.010V was attained (not the 0.001V it was set for).. This was a good start, or so I thought.
2- Unfortunately the balance indicator then turned off after approx 11 seconds. Repeat, repeat, repeat. So, you need a minimum current flowing into the battery of about 2.5A and even when everything is set to balance, and initiate this at 3.35VPC & a 0.001V imbalance, the balancing is not consistent nor is it continuous. Balancing "takes a break" approx every 10 seconds to 30 seconds (not at all consistent). 10-30 Seconds ON, 10-30 Seconds OFF, repeat, repeat, repeat. The longest duration I have measured balancing remaining ON is 59 seconds, but again, not consistent and no rhyme or reason as to why it is an ON/OFF behavior? It is typicall ON/OFF between 10 & 30 seconds.....?
3- I tried to re-program the zero amperage calibration and it will not stick. The minute you go back into the app, after programming the preferences, the change is wiped out. Thus no way I have found to override the 2 - 2.5A balance threshold for current (this also is not consistent).
4- This morning, at approx 14.25V (manufacturer recommended charge voltage 14.4V), after charging at 2.5A, the SoC was way off reading 76% SoC. This was with 14.25V at the terminals and 0.00A flowing into the battery (14.25V is a full battery and the Charge FETs were on and the battery accepting 0.00A. The following cell voltages were observed.
3.463V
3.687V
3.389V
3.706V
14.245V / Pack
5- I am back at it now with a delta voltage of 0.176V and balancing set to initiate at 3.32V and a 0.001V cell to cell differential, with 2.89A flowing into the cells. Balancing won't initiate at all. This Daly BMS seems to have a mind of its own? Settings changes seem to be a "feel good" measure only. By the settings and amperage this BMS should be balancing, based on the accepted settings (yes, the BMS has saved them) and it's not. It is the job of a BMS to balance cells.
This Daly BMS is the biggest cluster I've yet to see in any BMS. I've been doing custom built LiFePO4 since 2008 so not at all green at this. No matter what I have tried, this Daly BMS cannot and will not balance these 100Ah cells.
I am hoping someone has the answer because this is ridiculous, especially if this is how it is designed to operate. Oh, and apparently every-time you reset/re-program the app the cycle counter goes back to 0.......
How on Earth does Will rate this as a good BMS?
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And here's the rub. The vast majority of cells available to DIY's are horribly mismatched (we've capacity & IR tested well in excess of 600 cells). In excess of 80% of those cells (most for folks who were having issues) we would not build a bank from. Many of these cells came from highly recommended resellers on this forum.
If you have mismatched cells, which is very likely if you bought of Aliexpress etc., the Daly, IMHO, is the last BMS you'd want... Any good BMS design will shunt current from the high cell whether it is charging or not. Any good BMS design will use charger current to allow the battery to balance if the cells are at 100% and accepting no current. Any good BMS design will not turn ON/OFF balancing when it is necessary.
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John Frum
Tell me your problems
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I would not want this behavior on by default.
But I would like the option to enable it to deal with specific problems.
JBD has this behavior enabled by default so I turn it off as a matter of policy.
At a minimum the ability to enable / disable is always preferred. The Daly does not even give you this ability and thus it is impossisble for the Daly to balance the cells inside this battery without physically destroying the case and doing a manual top-balance. Cheap junk on both the cell front and BMS front have combined to make this battery as useful as a cinder-block...
Be very careful buying el-cheapo drop-in LFP batteries!!!
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Will not balance if no charge current <1.0A and bleed-off current is far too low. My multimeter doesnt respond fast enough to know exactly the rate is discharge, but it seems to average .012A-.020A, advertised specs are 0.035A. It appears to cycle rapidly to detect the cell votage then shunts through resistor, repeating this cycle rapidly. It would take many months for this to EVENTUALLY balance the cells, however, given that the unbalanced cells dont show their true colors until >3.42V, and also given that the BMS does not evenly report the cell voltages (its processor and update timing are off evidenced by the cyclic error) it only gets about 10 minutes at best to perform valuable balancing. This BMS is, for lack of better words allowed on this site, Absolute rubbish. There are no settings that will work to get this to perform better because for one, the last cell in the row shows the highest voltage as it charges rapidly, while the first row shows the lowest voltage - this is due to cell interconnect resistance. As it tapers off, the imbalanced cells will begin to appear, leaving just a few minutes at best to begin balancing. It does not allow for balancing as my charge controller holds the voltage at 3.45V per cell for instance, because by this time, the charge rate drops or cycles in/out of >1A. The processor on this thing is too slow, the balance rate is too slow, the time period to balance is too short and the period between testing cell voltage and draining through the shunt it is too short. Absolute rubbish.
Finally figured it out on my system.....
There is a hidden parameter available in sinowealth called ‘Balance open current’ that must be changed to 0 (or even negative) if you want to balance at low or zero current. It was set to 30mA on mine. Changing this to 0 will give you maximum balance time. Unfortunately the balance on Daly is a very small current (even less that the advertised value of (30/35? mA), so the more time you can spend balancing the better….. Time is your friend.
While you are in there…. Also change ‘DfilterCur’ to something reasonable like 200mA. That will give much better current display and more accurate SOC. This parameter is also partially why your balancing was so ineffective. I expect it to be around 1000 in your current system – and was causing your balancing to be disabled when the current was less than 1A!
There is a hidden parameter available in sinowealth called ‘Balance open current’ that must be changed to 0 (or even negative) if you want to balance at low or zero current. It was set to 30mA on mine. Changing this to 0 will give you maximum balance time. Unfortunately the balance on Daly is a very small current (even less that the advertised value of (30/35? mA), so the more time you can spend balancing the better….. Time is your friend.
While you are in there…. Also change ‘DfilterCur’ to something reasonable like 200mA. That will give much better current display and more accurate SOC. This parameter is also partially why your balancing was so ineffective. I expect it to be around 1000 in your current system – and was causing your balancing to be disabled when the current was less than 1A!
Hidden parameter? How do you get to the hidden parameters?
So my 16s 310 pack is top balanced, or as balanced as I could get it.
When should I care about balance? When its in float charge from the hybrid inverter or when its discharging?
In charge mode my diff is .2 or a little more, but if i unplug my hybrid inverter and let it run the inverter with the 1a draw or so it uses my diff voltage quickly goes to .007 or lower.
Im just not sure if im obsessing over having my cells balanced at the wrong time or not. When charging my high voltage protect cuts the charging with say cell 7 at 3.65 but cell 16 is only at 3.38.
Appreciate any advice.
John Frum
Tell me your problems
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Most diy batteries need significant bms intervention to maintain the balance as the cells tend to drift as they are cycled.
Balance should only happen above float voltage during charging.
If you balance at float voltage you will undo any top balance that have achieved.
From memory Daly BMS only balances during charging so that part is a non issue.
200 millivolts delta at the top is not well balanced at all.
Since it converges to 7 millivolts when the charge current is minimal, I think you may have a loose balance lead or a dirty connection point.
Meticulous preparation of all the joinery is essential for a diy battery.
The BMS should not have to disconnect during normal operation.
It means your pack is not properly commissioned or one or more of your cells are marginal.
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Appreciate the replies.
It goes real low as soon as any type of load is put on it, was just using the no load current draw of the inverter as an example.
Maybe disconnect was the wrong word. It stops charging when whichever of the cells gets over my set limit of 3.65
John Frum
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What goes real low?
Not at all sure we are understanding each other.
What is the "it" that is stopping charging?
The BMS should not have to intervene except for balancing in the normal operation of the system.
My differential cell voltage. From .2 while the hybrid inverter is in charge mode continuously trying to send more current to the bank but the bms cut charging since one or more cells hit 3.65.
Bms
Shouldn't it though? Otherwise won't the charger will just continue to charge.
My little system just sits on its bench not doing anything, always in charge mode. If I use it for a test and say unplug the ac feed from the hybrid inverter and run a heat gun for a little bit at 29a dc. Then kill the heat gun then plug the ac feed back in the inverter will begin to charge my system through the bms, and either the total over voltage protect or in my case individual cell voltage protect on the bms will trip and not allow any more charge into the battery until I play with it again or it drops below whatever voltage is needed to make the bms open back up.
John Frum
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Like I have said twice already, no it should not.
The battery should be sufficiently balanced and the the charger should be properly configured to work within the safe operating envelope.
I'm not going to say it again.
Oh ok sorry sir.
MisterSandals
Participation Medalist
BMSs disconnect. Chargers stop charging.
If you're using your BMS to do the job of a charge controller (get it? charge controllers are supposed to control the charging), you're using your system wrong and will likely put undue stress on the BMS and from what it sounds, your cells,
Think of the BMS as a battery safety disconnect that operates on several parameters like battery voltage, individual cell voltage and current.
The charge controller, it uh, controls the charging.
If your charge controller is not setup properly, your BMS should protect your battery. So you want to set your charge parameters to be more conservative than your BMS limits. If your battery has one cell hit 3.65V before the others, you NEED to set your battery charge voltage cutoff to be below that. Maybe its 13.8V or something to keep that from happening.
And i agree with everything that smoothJoey said.
John Frum
Tell me your problems
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@Jimmynik1 this doco may help.
The feature that distinguishes a charger from a power supply is charge termination.
diysolarforum.com
The feature that distinguishes a charger from a power supply is charge termination.
How charging works in the context of LFP batteries
How charging works in the context of LFP batteries
diysolarforum.com
I agree with everything too, it sounds very well put together and thought out. I like most people on here are trying to learn. I have about nine other hobbies and just got home from an 11 month deployment so I'm trying to figure out my little system.
Keep in mind no one was born knowing this information, it's literally still being developed everyday and continues to be dynamic. You might be great at telling people how to set up off grid solar systems and whatnot I might be great at working on small engines, but if you come to me for help I likely won't patronize you and understand you're just trying to learn like I am. I understand the charge controller controls charging.
That being said my system is 48v everything is through a hybrid inverter, eco-worthy 3500, your last line about having my charge controller settings more conservative than my BMS settings makes sense and I'm running through them now. "Battery boost charge voltage* is set to 57.6 by default. "battery floating charge voltage" is at 55.2 by default. There's 20 something other settings on this but those two seem like the ones to be conscious of, do those numbers look all right or should they be adjusted down?
Also say during a power outage with my system or anybody else's system running eventually the battery will to be depleted at that point no more AC will be generated by the inverter, in that scenario are we relying on the inverter low voltage cut off or the BMS low voltage cut off? Or is it the same as your recommendation above and have the inverter low voltage cut off set to a different voltage to not rely on just the bms?
This is right now messing around with it in my shop. Running a space heater on low at 6a ac or 15a dc. My app is somewhat unreliable for current draw I'm not sure if it's the connection but it fluctuates wildly even if the load is constant.
What I meant above is when the system is being used it appears to me as though they quickly go into balance or at least a better balance then when not being used almost immediately.
