Different batteries

[addision]

So I have watched a couple videos of different batteries being used in the same system. I have a Fortress that I just replaced and I was going to hook it up in my shed to some extra panels I had and get another small inverter.

Before I do that, is there a way for me to connect that Fortress to the same busbar as my new Eg4 batteries and have it charge and discharge correctly? I don't believe the BMS with the EG4's will work with the Fortress and that I Fi do this I would need to go to an open loop system.

Is there another device I could place in between that would monitor the different batteries and charge them correctly? Would this device then allow me to be closed loop with the inverters and the device would then control the charging? Or would it all stay open loop?

 

[ElectricIslander]

Separate dedicated small system would be best. You could fool around with stuff but you'd get unpredictable results.

 

[timselectric]

So I have watched a couple videos of different batteries being used in the same system. I have a Fortress that I just replaced and I was going to hook it up in my shed to some extra panels I had and get another small inverter.

Before I do that, is there a way for me to connect that Fortress to the same busbar as my new Eg4 batteries and have it charge and discharge correctly? I don't believe the BMS with the EG4's will work with the Fortress and that I Fi do this I would need to go to an open loop system.

Is there another device I could place in between that would monitor the different batteries and charge them correctly? Would this device then allow me to be closed loop with the inverters and the device would then control the charging? Or would it all stay open loop?

If the voltage and battery type is the same. It will work fine with open loop.

 

[addision]

OK, I feel I may want to go open loop now, many others don't appear to have a problem.

I would run the batteries to a busbar and that would allow me to use the Powerpro's with my existing Fortress. I hear a lot of mentions that the batteries must be of the same type. Both these batteries are LFP and appear to be rated 51.2v, although they have different capacities (360Ah compared to 280Ah). Are these the only specs I would need to know if I want to have them all connected to the same busbar?

Below are the specs for each battery and of course they are listed a little different. How do I know what setting to put into my inverter to satisfy the acceptable charging for both types of batteries? Would I need a third device in between the batteries and busbar to control the charge rate of the different batteries (battery banks)?

Fortress 18.5k
Total Energy (kWh) 18.5
Capacity[Ah] 360
Nominal Voltage [V] 51.2 (48)
Voltage Range[V] 48-55
Recommended Charge Current [A] 150
Max. Charge Current (Continuous)[A] 180
Max. Discharge Current (Continuous)[A] 180
Max. Pulse Current (for 10 sec) [A] 200

EG4
Total Energy Capacity 14.3kWh @25C, 100% SOC –
Voltage 51.2V –
Capacity 280Ah ±2% @25°C ±2°C @ 0.5C
Charging Voltage (Bulk/Absorb) 56.0V (±0.8V) 56.2V (±0.2V)
Float - 54V (±0.2V)
Low DC Cutoff 44.8V 47-45.6V (start higher, lower as needed)
Charge Current 100/140/200A Max. Continuous** 60 - 160A
Discharge Current 200A Max. Continuous 160A

I keep seeing different devices called out to use (shunt, charge controller, 3rd party BMS) but I am not sure if this is needed if I use the inverter. Unfortunately, no one says "If you have an inverter and want to go open loop then you would need these devices to help regulate charging and this is how they are different from these other devices". Is it because some of the device features overlap?

 

[timselectric]

Both these batteries are LFP and appear to be rated 51.2v

Bingo

although they have different capacities (360Ah compared to 280Ah).

Doesn't matter

How do I know what setting to put into my inverter to satisfy the acceptable charging for both types of batteries?

They're both the same type.

Would I need a third device in between the batteries and busbar to control the charge rate of the different batteries (battery banks)?

No
Just make sure that neither battery is receiving more than is recommended. (This can be adjusted on the fly)

I keep seeing different devices called out to use (shunt, charge controller, 3rd party BMS) but I am not sure if this is needed if I use the inverter. Unfortunately, no one says "If you have an inverter and want to go open loop then you would need these devices to help regulate charging and this is how they are different from these other devices". Is it because some of the device features overlap?

Each battery already has a BMS. So, strike that off of the list.
I'm assuming that your "inverter" is actually an AIO (All In One). Which includes a SCC (Solar Charge Controller) and an AC charger. So, strike this off of the list also.
A shunt like the Victron Smart Shunt, is very accurate for monitoring SOC (State Of Charge) of the entire battery bank. It is optional , but highly recommended.

 

[addision]

Wow, thanks for the response. Yes I have dual Sol-ark 12k AIO inverters.


Another question:

Would I need a third device in between the batteries and busbar to control the charge rate of the different batteries (battery banks)?

"No
Just make sure that neither battery is receiving more than is recommended. (This can be adjusted on the fly)"





Where would I look to make these changes per battery so that none is receiving more than the recommended amount? Would this be in the individual battery BMS?

 

[timselectric]

Wow, thanks for the response. Yes I have dual Sol-ark 12k AIO inverters.


Another question:


"No
Just make sure that neither battery is receiving more than is recommended. (This can be adjusted on the fly)"





Where would I look to make these changes per battery so that none is receiving more than the recommended amount? Would this be in the individual battery BMS?

Not per battery adjustable.
Adjust total, so that neither is exceeded.
Monitor it while charging. To see if adjustments are needed.

 

[addision]

That is great! You provided a large part of the information I was unsure of.

I was using my fortress battery in this manner for about two months before I could get a proper network cable and update the BMS to work with my inverter. It worked well. I wasn't sure if there was something special to do for using it this way with different batteries though.

 

[addision]

Ugh! I also found these settings as a sticky post. I often happens that I was just looking for the wrong search terms:

Charge Controller Settings

Looking to understand how to set up charge controller - DIY Battery: LF280K - 16 cell configured for 48V system with Overkill BMS - 18650 Grade A cells Charge Controllers - 2 Midnight Classic 200's - both running 2 strings of 6 panels rated at 380w each panel (12 panels x 380 = 4,560 watts)...

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