Daly BMS Balancing

[Lt.Dan]

Anybody know how to set a Daly BMS to balance without Charging? I know some other BMS like Overkill will do it as well.

Thanks,
Daniel

 

[Diysolar123]

you can set the overkill BMS units using their app (the daly just lets you set the balance start voltageas I recall), however...it really will do nothing at all in either case.
I set up a test to watch what the Daly (and overkill/jbd) bms units did with balancing and it is really only for very well matched batteries; a 10mv delta is beyond their ability to fix. Get a good active balancer and "poof"...all done.
I use something like this: (hw rev 1.3), the prices have gone up in the past 6months sadly. You attach it and your batteries will be nicely balanced within a few milivolts at full charge, well, thats how they work for me anyway.

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[Chael]

you can set the overkill BMS units using their app (the daly just lets you set the balance start voltageas I recall), however...it really will do nothing at all in either case.
I set up a test to watch what the Daly (and overkill/jbd) bms units did with balancing and it is really only for very well matched batteries; a 10mv delta is beyond their ability to fix. Get a good active balancer and "poof"...all done.
I use something like this: (hw rev 1.3), the prices have gone up in the past 6months sadly. You attach it and your batteries will be nicely balanced within a few milivolts at full charge, well, thats how they work for me anyway.

US 1.8V-4.5V 6~8S 5A Universal 4 LTO LFP LIPO Battery Active Equalizer Balancer | eBay

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This is exactly what I had to do. I have 16 EVE cells and the Daly BMS does a HORRIBLE job at balancing. I have this active balancer on the way

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[Iceman218]

Perhaps related, I have a Daly Smart 4s 250 AH BMS with bluetooth. It works fine under load, but does not let me change the balance voltage in the app. The default value is 0.26 V and I would like to drop that value down to 0.15 V or so. The other values are adjustable and it is not a password issue. Not a huge deal, but I always have a 0.1 to 0.15 high voltage cell and would like the Daly to bring it back to match the other 3 cells.

 

[Albert-CAV Tech]

Good Day.. I have a DALY BMS 30A discharge current/ 15A charge current. My Mppt solar controller registers 21A charging current at noontime. My question is that- is my BMS supposed to limit charging current to 15A; or cut-off charging if it exceeds 15A. Thank you for any reply and support

 

[carlrx7]

you can set the overkill BMS units using their app (the daly just lets you set the balance start voltageas I recall), however...it really will do nothing at all in either case.
I set up a test to watch what the Daly (and overkill/jbd) bms units did with balancing and it is really only for very well matched batteries; a 10mv delta is beyond their ability to fix. Get a good active balancer and "poof"...all done.
I use something like this: (hw rev 1.3), the prices have gone up in the past 6months sadly. You attach it and your batteries will be nicely balanced within a few milivolts at full charge, well, thats how they work for me anyway.

US 1.8V-4.5V 6~8S 5A Universal 4 LTO LFP LIPO Battery Active Equalizer Balancer | eBay

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Hello @Diysolar123 ,

What voltage does balancing start/end or does it balance at all voltage levels?

 

[Iceman218]

Is it a Daly Smart unit with bluetooth. If so the parameter tab let's you customize charge and discharge current separately. Could be the default values is not what you are suspecting but then again I am a neophyte regarding BMS.

 

[Jimmynik1]

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How about this guy here? Is it blue tooth only? Doesn't look like there is any screen or anything.
Looking to make a 24v bank with 16 cells with two sets of 8.

 

[Drago]

Anybody know how to set a Daly BMS to balance without Charging? I know some other BMS like Overkill will do it as well.

Thanks,
Daniel

May I know what is the purpose of balancing when battery is not charging ? A balancing is an additional battery discharging isn't ? Why to discharge a battery more than necessary ?

 

[Lt.Dan]

I would rather have a better balanced battery and be able to push it further into the knees, then to save a few watts.

My Daly is just barely not enough. Charging the battery up to 57v yields a 60mv deviation after 10 cycles or so. But the battery spends so much time in the upper knee, doing nothing since there is no charge current, when it could be balancing itself!

 

[Iceman218]

An active balancer will do that.

 

[Lt.Dan]

An active balancer will do that.

Yes, for more money, more wires and more BS. The BMS has it built in. Why not activate it somehow?

 

[Iceman218]

As a neophyte I do not know why my Daly Smart BMS which promised to balance will not let me change the 0.26V differential setting. My cells have two equal and one 0.05 higher and one 0.05 volt lower so my pack faults out before a full charge occurs. This is the job of the BMS but since I cannot adjust the 0.26V differential paying $30 for a heltec active balancer was cheaper than working with Daly to resolve my BMS issue. My time is more valuable.

 

[RCinFLA]

Most lower cost BMS do not do well with balancing when below the 3.4v level where cell voltage flattens out. Unfortunitely waiting until cell rises to 3.4v before balancing gives less time to do balancing before overvoltage on a cell is reached.

To do balancing in the relatively flat portion of cell state of charge region, the BMS must do simultaneous quick sampling of all cell voltages to avoid the cell voltage variations in time due to normal inverter or charger current fluxuations. Simultaneous sample and hold, or synchronous multiple ADC's to ensure all cell voltages are measured at same instant in time with same load or charge current is more BMS cost. Most low cost BMS's just average readings over time and sequence round robin the microcontroller's internal 12 bit ADC across all the cells. This is not accurate enough in the flat voltage region of cell state of charge to make correct cell balancing decisions.

Make sure you wire BMS sense wires consistantly so each BMS cell voltage sensing pair has only one bus bar in series with cell for BMS cell voltage monitoring.

 

[Iceman218]

Installed a Helco active 4s 12V balancer today the pack moved from a 0.12 to a 0.006 differential in hours. Very happy with this $30 balancer.

 

[Lt.Dan]

Still trying to figure out how to enable balancing without having to charge at the same time. I find my battery at 100% state of charge for most of the day, but will never actually balance because there is no charge current. Anybody?

Is there a parameter to change inside the PC software?

 

[RCinFLA]

Some BMS's don't balance unless charging. It makes it easy and cheap for the hardware not have to deal with high inverter discharge current upsetting the cell voltage comparison which is done at different points in time with averaging.

On one video I saw, Daly doesn't balance dump without sensing charging current even when BMS shuts down charging for cell overvoltage.

Many low cost BMS's do a round-robin cell voltage sampling with multi-sample averaging with the microcontroller internal 12 bit ADC. The time delay and averaging will cause cell terminal voltage variations due to inverter discharge or charging current changing over the round robin sampling cycle time.

When lower voltage balancing below 3.4v is used, cells get into flatter voltage part of discharge curve for LFP making any reading errors critical in making correct balancing decisions.

Finally, cells not truely matched can have cell terminal voltage overpotential variations due to dscharge or charge current level that can screw up balancing decisions in the flat portion of discharge curve.

If BMS restricts its balancing to greater than 3.4v it stays out of flatter portion of battery curve and ensures it is not getting influence of large cell currents on its terminal voltage. If inverter draws a significant discharge current, no cell will be over 3.4v even if it was fully charged.

 

[Iceman218]

Add a Helac active balancer for about $20 and your pack will balance without charging. A BMS is not good at balancing but does a great job of protecting the cells. My pack now is at less that 0.006 V difference whereas before the Helac AB it was off 0.2V

 

[Lt.Dan]

Add a Helac active balancer for about $20 and your pack will balance without charging. A BMS is not good at balancing but does a great job of protecting the cells. My pack now is at less that 0.006 V difference whereas before the Helac AB it was off 0.2V

I dont want an active balancer because my BMS will do just a fine job IF I can enable balancing on it.

I'm not asking to balance below 3.4v, im asking to balance when at 3.5+ specifically. My battery spends 5+ hours a day at 100% (with some cells at 3.6v), while the BMS could be balancing entirely on its own and keeping the batteries at a nice 3.50-3.55v.

Right now I'm trying to push them up as close to 3.65v as possible to give the BMS more time to balance, but it just gets there too fast.

 

[Iceman218]

My Daly Smart 250 AH BMS has never been able to balance when charging to less than 0.1V regardless of the upper voltage limit. I never let mine get above 3.55V per cell anymore as it does not help long term health of the cells. Not sure why you do not want to add an active balancer as if you did, that would be your last post about the Daly not doing its job. But this is America where we each choose our choice. I understand an active balancer is really just doing what a more expensive BMS would do with out an active balancer. If you figure out how to balance with the Daly when not discharging, let us know. The Daly keeps all my cells balanced on its own only during discharge.