Signature Solar 24v EG4-LL unbalanced and Low capacity with SoC at 100%

[LithiumCanuck]

I installed 3 EG4-LL batteries about a month ago in my cabin and I didn’t have any issue until today. When I arrived today, I looked at my batteries state to see how they are doing. SoC is at 100% for all three. Two seem in a perfect state but one is showing a cell OV status, low capacity status and the cells are unbalanced. Something to worry about or not?

Note: pack ID2 is not showing but it’s similar to ID3

 

[sunshine_eggo]

I installed 3 EG4-LL batteries about a month ago in my cabin and I didn’t have any issue until today. When I arrived today, I looked at my batteries state to see how they are doing. SoC is at 100% for all three. Two seem in a perfect state but one is showing a cell OV status, low capacity status and the cells are unbalanced. Something to worry about or not?

Note: pack ID2 is not showing but it’s similar to ID3
View attachment 99932

This is a shit show of epic proportions. You can see it's trying to balance all cells but #4.

Recommend you reduce absorption to 27.6V and float to 27.2V. Allow for up to 6 hours of absorption time.

Hopefully, that will give the BMS more opportunity to balance the cells.

I would certainly let @RichardfromEG4 know. I would not expect this with newly installed batteries.

 

[LithiumCanuck]

Recommend you reduce absorption to 27.6V and float to 27.2V. Allow for up to 6 hours of absorption time.

I’ll update my settings with these numbers and see what happens tomorrow. I still don’t understand why the low capacity alarm is showing though. Maybe @RichardfromEG4 will know…

 

[sunshine_eggo]

I wouldn't be surprised if the BMS considers a substantial imbalance (0.429V is a mile) problematic and arbitrarily reports low capacity. It may be that it's detected a problem with one or more of the cells based on a past discharge, and that condition is triggered, which likely would contribute to imbalance.

 

[LithiumCanuck]

After a good diner and a few beers (no I am not touching any wires after having beers), I went to see how pack#4 was doing…. Everything is back to normal. But I still need to know what’s going on during sunny days.

 

[Alkaline]

This is a shit show of epic proportions. You can see it's trying to balance all cells but #4.

Recommend you reduce absorption to 27.6V and float to 27.2V. Allow for up to 6 hours of absorption time.

Hopefully, that will give the BMS more opportunity to balance the cells.

I would certainly let @RichardfromEG4 know. I would not expect this with newly installed batteries.

We need Robby to discuss this he knows about this setup from Ganfeng.

 

[offgriddave]

Fully charge, then some more. Then flip off and then on switch to turn off the BMS ("reset it"). This is what fixed my 48v pack. The charge indication started lagging behind the actual state of charge of the battery. Don't trust the EG4-LL charge measurement.

 

[robby]

We need Robby to discuss this he knows about this setup from Ganfeng.

I have created another thread on this topic with my own issues.
https://diysolarforum.com/threads/o...sted-energy-while-charging.42244/#post-535002

Anyway OP welcome to my world as an EG4LL owner. There are ways to get the cells balanced again but the annoying part is that it keeps happening every few weeks. If you don’t catch it you have nights when the batteries don't run as long and then when you realize why it’s happening, it's the cells out of balance. You then have to go back through another long balancing session again to get back capacity.

 

[sunshine_eggo]

After a good diner and a few beers (no I am not touching any wires after having beers), I went to see how pack#4 was doing…. Everything is back to normal. But I still need to know what’s going on during sunny days.

This is not "normal." This is discharging cells in the working voltage range. Even severely imbalanced cells will have negligible voltage deviations between the charge and discharge legs.

 

[LithiumCanuck]

Ok…. More information to try to understand what is going on… Woke up this morning, all 3 batteries were at 85%-86% and all cells were at the same voltage within 1-2 millivolts. Nice sunny day, the batteries are charging, still within 1-2 mV until they reach 100%. At that point, current drops to 0.000 then the cells voltage start to go in all directions…

(problematic battery is #2 and is always a couple %SoC below the other 2)

 

[sunshine_eggo]

Ok…. More information to try to understand what is going on… Woke up this morning, all 3 batteries were at 85%-86% and all cells were at the same voltage within 1-2 millivolts. Nice sunny day, the batteries are charging, still within 1-2 mV until they reach 100%.

Again, cells outside the upper and lower legs will always be very close in voltage even when imbalanced.

At that point, current drops to 0.000 then the cells voltage start to go in all directions…

This is classic over-voltage protection behavior due to cell imbalance.

(problematic battery is #2 and is always a couple %SoC below the other 2)
View attachment 100232

#2 is likely to experience a little less charge and a little less load when initially applied. Shouldn't really matter much.

Would triple check that all the connections are tight.

Did you reduce absorption? Do you have any numbers for us to see?

 

[LithiumCanuck]

Did you reduce absorption? Do you have any numbers for us to see?

I did, but I wasn't able to make it longer... Max is 180 minutes.

I left in a rush, so I forgot my notepad. I will go back this week and show you my numbers.

Edit: I was thinking swapping #2 with #3 to see if center one is still lower...

Thanks again.

 

[Kornbread]

At what voltage, or what part of the charge cycle does the eg4 bms balance the cells?

 

[TomC4306]

SOC is a derived number, not a direct measurement. Therefore, in my parallel bank, I only use combined, average SOC as general information.
The real, direct measurement of the paralleled batteries relative balance is average cell voltage and mine track within 2 or3 mv of one another.
Also, one of my packs charges ahead of the others (soc) and discharges ahead of the others. They all come together (soc) at the top and are closer at the bottom.

 

[Solar Guy Richard]

Hey all, I was on vacation just got back today. Have you contacted SS on this to get a ticket created?

 

[LithiumCanuck]

Hey all, I was on vacation just got back today. Have you contacted SS on this to get a ticket created?

Hey Richard, I hope you had a great vacation. I didn’t expect you to reply during the weekend, don’t worry ?.

I didn’t open a ticket because it was the end of the week (well at least on the East side). I thought I could get some info here during the weekend. I will open one now.

 

[LithiumCanuck]

Oh. Just to add more info. According to the BMS, I am still on the first cycle of the batteries and I read at a couple of places that it takes « a few cycles » to set things up. I ran out of electricity a couple of times last winter so when I bought my new batteries, I said « never again ». So I will have to disconnect my panels if I want to go below 80%.

Which brings me to this question. How low do I have to go to complete a discharge cycle?

edit: is a complete cycle from below 65% to above 90% ?

 

[Solar Guy Richard]

Oh. Just to add more info. According to the BMS, I am still on the first cycle of the batteries and I read at a couple of places that it takes « a few cycles » to set things up. I ran out of electricity a couple of times last winter so when I bought my new batteries, I said « never again ». So I will have to disconnect my panels if I want to go below 80%.

Which brings me to this question. How low do I have to go to complete a discharge cycle?

edit: is a complete cycle from below 65% to above 90% ?

Lithium measures cycles in total AH used. So essentially every 100AH is 1 cycle.

 

[robby]

Lithium measures cycles in total AH used. So essentially every 100AH is 1 cycle.

Thats good to know, thanks. Fortress power also uses 100-0% SOC as one cycle but I know that some other companies play games and say it's 100-20%.

 

[LithiumCanuck]

Ok.

I reduced absorption like @sunshine_eggo suggested a few days ago. When I got there 2 days ago, the battery was in a better condition though still not perfect. I used what I had there to drop SoC below 65% (took me all day), plugged back the panels then left.

I also got a reply from SS (same day I opened the ticket). They suggested that I reset the batteries. I‘m going back tonight. I’ll reset all 3 and see what happens.

 

[Koldsimer]

I think they just need some time (2+hrs) to balance while fully charged.

I'd keep absorb voltage at 56.5 but increase your time to 2hrs. You will notice the bms going through cycles of rapid charging and discharging while the cells are balancing. This will only happen when the battery is 100% soc. It took a couple weeks for my batteries to sync up and consistently hit 100% soc.

That being said, i still have nearly 200mv differences in two of my modules after a full charge. Grade a cells huh? Probably not. Hopefully the capacity is as rated.

 

[robby]

I think they just need some time (2+hrs) to balance while fully charged.

I'd keep absorb voltage at 56.5 but increase your time to 2hrs. You will notice the bms going through cycles of rapid charging and discharging while the cells are balancing. This will only happen when the battery is 100% soc. It took a couple weeks for my batteries to sync up and consistently hit 100% soc.

That being said, i still have nearly 200mv differences in two of my modules after a full charge. Grade a cells huh? Probably not. Hopefully the capacity is as rated.

Yep exactly and then one low discharge down to 10% followed by next day being cloudy or rainy and you cannot get them back to 100% they then get stuck in the 91% area and you have to repeat the whole thing again.
Basically any day when I have two straight days of bad weather I am going to be in problems.

No they are not Grade A cells, the actual manufacturer is honest enough to spell that out on their website.
I have three cells that have a lot more issues than the rest. If those EG4 Lifepower guys had easy access to cell voltage data they would be surprised at what they might find.

 

[ColtB45]

No they are not Grade A cells, the actual manufacturer is honest enough to spell that out on their website.
I have three cells that have a lot more issues than the rest. If those EG4 Lifepower guys had easy access to cell voltage data they would be surprised at what they might find.

As someone who just bought 3 EG4's I would be very interested in this. Do you have a link?

 

[LithiumCanuck]

As someone who just bought 3 EG4's I would be very interested in this. Do you have a link?

Google communication rack mount batteries and look at images. You will find them.

 

[robby]

As someone who just bought 3 EG4's I would be very interested in this. Do you have a link?

http://www.ganfenglithium.com/pro3_detail_en/id/173.html