Hi from Ukraine. Need help in EAsun 6.2 KW 48v + 150Ah LiFePo4 battery setup

[elf_ua]

Hey guys,

I need help in voltage setup for EAsun 6.2 KW (7000 VA) 48V + 3x parallel Eco-worthy battery packs (51.2V) with BMS on each other, but can't communicate with inverter. Do have a few questions.
1) Is it possible and make sense to replace BMS in the batteries for the ones with Bluetooth or RJ45 port? What's the BMS inside that batteries?
2) The maximum voltage for Low DC cut-off is 48v. It seems it's near 9.5% energy left. Is it a problem? I wanted to leave at least 15% (50.4V), but no way set this amount, there is only 40-48V range.
3) Please suggest floating and bulk voltages. I set Floating - 52.2 V and Bulk - 53.6 V
4) Is it OK 60A charge current for the 150AH units?

 

[sunshine_eggo]

Hey guys,

I need help in voltage setup for EAsun 6.2 KW (7000 VA) 48V + 3x parallel Eco-worthy battery packs (51.2V) with BMS on each other, but can't communicate with inverter. Do have a few questions.
1) Is it possible and make sense to replace BMS in the batteries for the ones with Bluetooth or RJ45 port? What's the BMS inside that batteries?
2) The maximum voltage for Low DC cut-off is 48v. It seems it's near 9.5% energy left. Is it a problem? I wanted to leave at least 15% (50.4V), but no way set this amount, there is only 40-48V range.
3) Please suggest floating and bulk voltages. I set Floating - 52.2 V and Bulk - 53.6 V
4) Is it OK 60A charge current for the 150AH units?

1) maybe. You won't know until you open them. Inverter comms are often NOT used even when available. I wouldn't bother with the extra effort and expense unless you have a COMPELLING need for comms.
2) Not a problem.
3) 51.2V indicates 16 cells. Your voltages are WAY too low. Slow charge 3.45V/cell with a 2-4 hour absorption. Fast charge 3.55-3.65V/cell with a 15-30 minute absorption time. Float 3.375V/cell. Note that with comms, these values are ignored, and the BMS controls charging.
4) 150Ah per battery or 150Ah total? Most cells are rated for at least 0.5C or 75A per 150Ah in your case. They likely recommend charging at 0.2C or 30A per 150Ah for maximum cycle life.

 

[elf_ua]

1) maybe. You won't know until you open them. Inverter comms are often NOT used even when available. I wouldn't bother with the extra effort and expense unless you have a COMPELLING need for comms.
2) Not a problem.
3) 51.2V indicates 16 cells. Your voltages are WAY too low. Slow charge 3.45V/cell with a 2-4 hour absorption. Fast charge 3.55-3.65V/cell with a 15-30 minute absorption time. Float 3.375V/cell. Note that with comms, these values are ignored, and the BMS controls charging.
4) 150Ah per battery or 150Ah total? Most cells are rated for at least 0.5C or 75A per 150Ah in your case. They likely recommend charging at 0.2C or 30A per 150Ah for maximum cycle life.

Thank you for the reply.
1) OK, thanks. That was a question I was thinking of too much.
2) ++
3-4) 150AH total. The default value was 56.4V for the Bulk charge. But if it's being controlled by BMS, is there any reason to play with values? 55.2 v for 16 cells would be fine for 4 hours charge? I want to charge my batteries for the 4 hours (because of potential blackouts after missile strikes. We were limited in 3-4 hours of electricity per day). I think 0.4C shouldn't be a problem for this period. In the peaceful time I will set up 0.2C for sure.

 

[elf_ua]

BTW, bought 3.2KW/ 24V (100 AH) system for my parents. Should I divide voltage values (bulk, floating, etc) for 2?

 

[elf_ua]

And about floating voltage, I read that voltage is not necessary to keep in high range because of almost no self-discharge in LiFe and even lower values rather then 52.2V were suggested. But 54V was the default in my system

 

[sunshine_eggo]

Thank you for the reply.
1) OK, thanks. That was a question I was thinking of too much.
2) ++
3-4) 150AH total. The default value was 56.4V for the Bulk charge. But if it's being controlled by BMS, is there any reason to play with values? 55.2 v for 16 cells would be fine for 4 hours charge? I want to charge my batteries for the 4 hours (because of potential blackouts after missile strikes. We were limited in 3-4 hours of electricity per day). I think 0.4C shouldn't be a problem for this period. In the peaceful time I will set up 0.2C for sure.

With 50Ah batteries, it's critical that you wire the batteries so they are well balanced and flow the same current. Charging at 60A means it might be too much if the batteries aren't balanced. See link #6 in my signature.

BTW, bought 3.2KW/ 24V (100 AH) system for my parents. Should I divide voltage values (bulk, floating, etc) for 2?

It's still the same cell values, just *8 instead of *16.

And about floating voltage, I read that voltage is not necessary to keep in high range because of almost no self-discharge in LiFe and even lower values rather then 52.2V were suggested. But 54V was the default in my system

Are you placing these in storage, or are you using them? If placing in storage, no float necessary. If using them in a system, the float voltage is used by the SYSTEM as a minimum battery voltage to maintain and use the PV to power loads. If float is too low, the battery discharges to that level before PV starts powering loads.

3.375V/cell allows the batteries to *slightly* discharge once charging stops, and then they are held at near full charge while the PV powers the system.

 

[elf_ua]

With 50Ah batteries, it's critical that you wire the batteries so they are well balanced and flow the same current. Charging at 60A means it might be too much if the batteries aren't balanced. See link #6 in my signature.

Wow! That a great idea to use busbars, I'll order copper plates ASAP for this. Temporary I will connect 3 batteries diagonally. Thank you for the info, it's very useful (as well as other suggesioons)

Are you placing these in storage, or are you using them? If placing in storage, no float necessary. If using them in a system, the float voltage is used by the SYSTEM as a minimum battery voltage to maintain and use the PV to power loads. If float is too low, the battery discharges to that level before PV starts powering loads.

Till there is no power cuts it's in storage mode ( I don't have solar panels yet and won't have till the spring). But we are expecting blackouts, as was in previous winter. In that case the battery system will be actively used. I caught the idea, I will set 3.375V/cell then the batteries will be used.

Thank you so much! Appreciate the help!