storage increase

[lucadea85]

Hi, I have a battery bank with 16 cells of 230Ah by amy, seplos bms 150A. can I parallel other 16 cells of 280Ah or do I have to necessarily put 230Ah?

 

[gokalex]

You can parallel batteries with different Ah, if they have the same chemistry it's best.

the bigger battery (280Ah) will take a bit more of the load of the smaller one

Just make sure that when you connect them together the voltages are similar or you will get one battery pushing amps in the other one. (with lifepo4 since the voltage curve is very flat you will not usually get many amps flowing as long as the two batteries are between 20 and 80%, but you should still try to have them at the same SOC)

Also each battery should have it's own fuse on the positive side

 

[lucadea85]

OK thanks. I should buy lifepo4 cells while I recovered 32 65Ah agm cells ... can I parallel with these? I've seen some discussions where this was done successfully ...

 

[gokalex]

Since different chemistries have different charge/discharge parameters/curves it would be best to use the same "type" of cells

It is "possible" to parallel them, but probably not recommended

 

[Rossman]

agm cells ... can I parallel with these?

Absolutely not, AGM and lithium have different charging requirements, and voltage limits

 

[acdoctor]

I am not a fan of parallel cells under one bms of the same capacity. You definitely would need a new bms and parallel batteries not parallel cells. Best case scenario with parallel cells of 230 and 280 is all would be restricted to the 230.

 

[BobR]

Hi, I have a battery bank with 16 cells of 230Ah by amy, seplos bms 150A. can I parallel other 16 cells of 280Ah or do I have to necessarily put 230Ah?

google 'victron lead acid parallel lifepo4'. There are several discussions on that subject there.

 

[wattmatters]

Absolutely not, AGM and lithium have different charging requirements, and voltage limits

I'm running 200 Ah of LiFePO4 in parallel with 400 Ah of SLA in a 48 V system and the charge parameters are just fine for my combination.
It's going to depend on the specifications of your particular batteries.

 

[lucadea85]

I'm running 200 Ah of LiFePO4 in parallel with 400 Ah of SLA in a 48 V system and the charge parameters are just fine for my combination.
It's going to depend on the specifications of your particular batteries

my lifepo4 battery bank is DIY with 16 cells 230ah by Amy and seplos bms. the lead batteries are the Fiamm 12FGL70. I have 32 pieces available.

 

[wattmatters]

my lifepo4 battery bank is DIY with 16 cells 230ah by Amy and seplos bms. the lead batteries are the Fiamm 12FGL70. I have 32 pieces available.

https://docs.rs-online.com/dd01/A700000006437184.pdf

Float voltage at 20°C is 2.27 V/cell x 24 = 54.48 V

54.48 V / 16 LiFePo4 cells = 3.405 V/cell

Float for Lead varies with temperature so if you are in a warm climate then you can knock that down a bit.

My float is set at 54 V which is 3.375 V/cell (on average) but frankly the LiFePO4 just never sit at float, the LiFePO4 is typically either charging or discharging - meanwhile the Lead sits there happily at float level pretty much the whole time. Its purpose is as backup storage for outages and to act as system ballast.

 

[lucadea85]

I installed 4 lead batteries 70Ah in series to test and it works. Connected in parallel with the lithium and I tried to do a complete charge and discharge of the system but I don't see any increases in capacity ... maybe I have problems with charging the lead because when the lithium reaches 56.5v the bms can bus communicates to the victron inverter to suspend charging?