calculating battery discharge current to BMS to inverter? sizing?

[Jamie.sanders]

Need some help guys, im looking at a Samlex 24 volt 3,000 watt inverter. it has a max input of 180Amps
I am running 3 24 volt 280AH LI batteries in Parallel. Battery specs says Nominal discharge 140A, max discharge current 280A
Each 24 volt battery is made up of 8 lithium ion cells, to make a 24v battery, so I will need 3 BMS's (1 per 24V battery made up of 8 cells)
If I wire in parallel the amp hours increase, so what size BMS? will this inverter work well with this system?

if it matters I have a Midnight Solar classic 150 charge controler? help??? please!

https://invertersrus.com/wp-content/uploads/2018/02/Samlex-PST-3000-24-Spec-Sheet.pdf

 

[FilterGuy]

Battery specs says Nominal discharge 140A, max discharge current 280A

Do you mean Cell Spec? (A battery is made up of a group of cells).

im looking at a Samlex 24 volt 3,000 watt inverter. it has a max input of 180Amps

The 180A must be a max surge current. The reason I say that is that even at only 85% efficiency, the nominal input current at full load should only be
(3000W/12V)/.85%=147A.

However, let's use 180A to be safe. If you have 3 batteries in parallel, then each would have to supply 1/3 of the current or 180A/3=60A

You may want to go higher than 60A though. As an example, you could go with 100A and you would be able to keep running on two batteries if one of them failed. (180A/2=90A).

The Overkill 100A, 24V BMS might be a good option. (I have experience with these and they are good BMSs)
The JK BMSs seem to be well-reviewed and gaining popularity on the forum. (I do not have experience with these)

Note: There is a 200A JK that you could use wire up a single battery in a 3P8S configuration and a single 200A JK BMS.
Some folks on the forum don't like parallel-first cell arrangements like this, but if you have halfway decent cells, it would work just fine. (Particularly with the built-in active balancing of the JK)

The upside of parallel first is simplicity and cost.
The downsides of parallel first is that 1) you can not monitor each cell individually and 2) there is no redundancy.

Cell Configurations for 12V 24V and 48V LiFePo4 Batteries

This short deck shows 1P and 2P cell configurations for 12V, 24V & 48V LiFePO4 batteries. To get the deck, click on the orange button at the top of this page. Note: Reviews, Comments and corrections are welcome Document Revision History...

diysolarforum.com

 

[Jamie.sanders]

Do you mean Cell Spec? (A battery is made up of a group of cells).


The 180A must be a max surge current. The reason I say that is that even at only 85% efficiency, the nominal input current at full load should only be
(3000W/12V)/.85%=147A.

However, let's use 180A to be safe. If you have 3 batteries in parallel, then each would have to supply 1/3 of the current or 180A/3=60A

You may want to go higher than 60A though. As an example, you could go with 100A and you would be able to keep running on two batteries if one of them failed. (180A/2=90A).

The Overkill 100A, 24V BMS might be a good option. (I have experience with these and they are good BMSs)
The JK BMSs seem to be well-reviewed and gaining popularity on the forum. (I do not have experience with these)

Note: There is a 200A JK that you could use wire up a single battery in a 3P8S configuration and a single 200A JK BMS.
Some folks on the forum don't like parallel-first cell arrangements like this, but if you have halfway decent cells, it would work just fine. (Particularly with the built-in active balancing of the JK)

The upside of parallel first is simplicity and cost.
The downsides of parallel first is that 1) you can not monitor each cell individually and 2) there is no redundancy.

Cell Configurations for 12V 24V and 48V LiFePo4 Batteries

This short deck shows 1P and 2P cell configurations for 12V, 24V & 48V LiFePO4 batteries. To get the deck, click on the orange button at the top of this page. Note: Reviews, Comments and corrections are welcome Document Revision History...

diysolarforum.com

Thanks for the detailed answer, one question, Will the Samlex 24 volt 3,000 watt inverter work well with this?

as for the battery info you ask about, they are Eve LF280K cells, the spec sheet says:
Eve LF280K

280Ah:

Nominal Capacity:280Ah(IC)
Nominal Voltage:3.2V
Operating Voltage:2.5-3.65V
Max charge voltage 165
Max charging current 280A
Nominal Discharging Current:140A
Max Discharging Current: 280A
Working Temperature: Charge:0℃~55℃
Discharge:-30℃~55℃
Storage Temperature:-30℃~60℃
Dimenson:Thickness:71.57± 0.50mm
Width:174.00±0.50mm
Shoulder height: 200.37±0.60mm
Total height : 203.11±0.60mm
Cell Weight: 5.27±0.16kg
Energy Density:170Wh/kg

 

[FilterGuy]

Will the Samlex 24 volt 3,000 watt inverter work well with this?

Sorry..... I am not following the question. What 'this' are you referring to?

 

[Jamie.sanders]

Sorry..... I am not following the question. What 'this' are you referring to?

The rest of the system, batteries and their output, inverter if I matters.

 

[FilterGuy]

Yes, Either 3 1P8S batteries with 3 100A BMSs or a single 3P8S battery with a single 200A BMS should work fine.

 

[Jamie.sanders]

Yes, Either 3 1P8S batteries with 3 100A BMSs or a single 3P8S battery with a single 200A BMS should work fine.

Sweet, thank you