Daly 200A BMS odd readings

My system consists of 400W of Renolgy solar panels, 280aH LifePO4 battery, EPEver MTTP charge controller, 3KW inverter and the 200A Daly BMS. All connections are secure and my balance wires are attached to the buss bars via tapped holes using screws. All grounds (2AWG) go to a buss bar and are attached to a hefty frame ground.

Everything seemed to have been working great over the last few months but last week I started noticing some odd behavior. At first the inverter would randomly fault for input voltage being low. This did not make any sense as the battery voltage never got below 3.2 volts per cell (12V system). Next, during the night all power got shut off. I found the BMS had shut down so I checked all connections and reset the BMS. Things worked for the rest of the night.

The next day it was faulting more regularly so I hooked up the laptop and did some datalogging (see attached). What I found was quite interesting. It almost looks like a buffer issue in the BMS. The BMS would get low voltage readings of 4V (2mV cell 1, 624mV cell 2, 2702mV cell 3 and 2201 cell 4). Temp readings seemed way off and the current reading went up to 2460 amps!!... yea, something seems off!! The load at the time was a only a few amps worth consisting of mostly USB charging. I bypassed the BMS and had zero issues. Any idea what is going on here??

Appreciate the help -
 

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curiouscarbon

Science Penguin
After reading the behavior and the indicated readings, perhaps the BMS is defective and needs to be repaired or replaced.

Have heard many stories of Daly BMS malfunctioning. I’m sorry. Wish I could offer more detailed advice 🙂
 
That is not the answers I'd like to hear :-(. It was working great though!! Guess I will reach out to Daly to see if they can warranty it. I wish there were more options available that were priced decent / inexpensive.
 

curiouscarbon

Science Penguin
That is not the answers I'd like to hear :-(. It was working great though!! Guess I will reach out to Daly to see if they can warranty it. I wish there were more options available that were priced decent / inexpensive.
If you wish for a recommendation, I suggest looking for JBD BMS.

I built (still operating) a 12V pack with 100Ah frey/fortune/overkillsolar cells and 12V 120A 4S JBD brand BMS from overkillsolar. I love that BMS.

Right now overkillsolar is SWAMPED.


Current connected is offering 12V 150A 4S BMS for 165 USD. I have never bought from them. I have never used the 150A model JBD BMS. Only 120A 12V from overkillsolar.

Some people are buying JBD BMS from alibaba and that’s an option but I prefer to purchase from supplier in same country.

Good luck and please feel free to ignore this 😅 just sharing my experience.

The shiny red Daly BMS caught my eye too. Don’t worry though, the JBD looks boring but that’s because it is boring in the best way 😇

may yer projects go smoothly
 
If you wish for a recommendation, I suggest looking for JBD BMS.

I built (still operating) a 12V pack with 100Ah frey/fortune/overkillsolar cells and 12V 120A 4S JBD brand BMS from overkillsolar. I love that BMS.

Right now overkillsolar is SWAMPED.


Current connected is offering 12V 150A 4S BMS for 165 USD. I have never bought from them. I have never used the 150A model JBD BMS. Only 120A 12V from overkillsolar.

Some people are buying JBD BMS from alibaba and that’s an option but I prefer to purchase from supplier in same country.

Good luck and please feel free to ignore this 😅 just sharing my experience.

The shiny red Daly BMS caught my eye too. Don’t worry though, the JBD looks boring but that’s because it is boring in the best way 😇

may yer projects go smoothly
Unfortunately I need one capable of at least 200 amps. The largest one they show available is 150A. Back to the drawing board I guess??
 
I have been going back and forth with Daly on this problem. It is blatantly obvious that they believe the problems I am experiencing is my fault. They are blaming either my wiring or batteries. I have asked multiple questions that they refuse to answer. It is frustrating to flush $200 down the drain!! Here is a pic of my wiring - see anything wrong??
 

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curiouscarbon

Science Penguin
I have been going back and forth with Daly on this problem. It is blatantly obvious that they believe the problems I am experiencing is my fault. They are blaming either my wiring or batteries. I have asked multiple questions that they refuse to answer. It is frustrating to flush $200 down the drain!! Here is a pic of my wiring - see anything wrong??
Haha man I don’t know but if I made the thing in your photo I’d feel pretty damn proud.

You got the balance leads perfectly equidistant from the cells they address, Perfectly bent constraining panel.. Bent corner strong!! Must have had to do kappa math to get that one.. or something.

Anyways what I’m saying is your pack looks fabulous and I personally avoid DALY because of too many weird stories of malfunctions. All the high amp daly bms are imported designs, I read, only the low amp ones are actually *designed by daly*. Like the 60A one.

Cheers and hope you get up and running soon.
 
I figured I would post a follow-up to my thread. Daly has been surprisingly responsive to my questions and concerns so I give them props for the support they have given me. I did some bench testing using a huge box fan and an inverter trying to figure out what is going on. My findings were that because I had the sensor wire connectors under the main battery cables (B+ & B-) it was introducing some resistance that was perceived as voltage drop. The BMS would see the drop which would cause it to shut down. I made 2 new tabs and tapped them for a screw terminal (see picture) like the other wires. After finishing, my voltages were rock solid and the BMS seems to be working great except I am left with 1 problem. 3 of the 4 cell voltages are dead on when compared to my fancy Fluke meter. Unfortunately Cell 1 is actually reading ~0.1 volts lower than it actually is. With these types of batteries, 0.1 volts is a ton! When you factor in that it will also try and charge/balance it to the voltage it believes it needs to be at, damage can occur. I will post once again in a few days if we figure out why the lower readings on the one cell.
 

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I would parallel the cells and do a new top balance.
They all measure exactly the same via a multimeter (within 0.002V). No reason to top balance them if they are the same to begin with. I did do it a couple months ago when I put the battery into service. Thanks for the suggestion...
 

Lt.Dan

Photon Sorcerer
I have been going back and forth with Daly on this problem. It is blatantly obvious that they believe the problems I am experiencing is my fault. They are blaming either my wiring or batteries. I have asked multiple questions that they refuse to answer. It is frustrating to flush $200 down the drain!! Here is a pic of my wiring - see anything wrong??
I would like to see your main cell negative lead on top of your large cable, not underneath it.
 
BTW, it talking with the tech support at Daly, it is "normal" for the BMS to report very high currents and also show odd readings on the other sensors when it switches between charge and supply. I thought it was a bit odd but they say it is normal and by design!
 

Sjaxkingpin

New Member
I figured I would post a follow-up to my thread. Daly has been surprisingly responsive to my questions and concerns so I give them props for the support they have given me. I did some bench testing using a huge box fan and an inverter trying to figure out what is going on. My findings were that because I had the sensor wire connectors under the main battery cables (B+ & B-) it was introducing some resistance that was perceived as voltage drop. The BMS would see the drop which would cause it to shut down. I made 2 new tabs and tapped them for a screw terminal (see picture) like the other wires. After finishing, my voltages were rock solid and the BMS seems to be working great except I am left with 1 problem. 3 of the 4 cell voltages are dead on when compared to my fancy Fluke meter. Unfortunately Cell 1 is actually reading ~0.1 volts lower than it actually is. With these types of batteries, 0.1 volts is a ton! When you factor in that it will also try and charge/balance it to the voltage it believes it needs to be at, damage can occur. I will post once again in a few days if we figure out why the lower readings on the one cell.


I just popped in to to say that is a BOSS job on that battery!!!
 
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