Conext sw4024 - LifePO4 requirements ?

[bluefin99]

I have had a Conext SW4024 inverter/charger running off a 24v battery setup ( 4 ea. 6V Rolls deep cycle...200 AH ) at my cabin. Batteries are also charged by 1200watts of solar through a 100 amp Renogy controller. I need to replace batteries and would like to go LifePO4. According to my manual, my Schneider Conext can manage lithium batteries. So..looking for resources to help me understand:
- are there specific requirements that I need to adhere to when shopping for batteries,
- i am looking to go with 2 ea. 250 to 300 Ah 12v batteries wired in series to give me a 24v system. Should I look for a bigger 24V battery instead ?
As you can likely tell, I have lots to learn to ensure I match my power needs with the right solution. The owners manual doesnt really tell me much..
thx

 

[BentleyJ]

- i am looking to go with 2 ea. 250 to 300 Ah 12v batteries wired in series to give me a 24v system. Should I look for a bigger 24V battery instead ?

YES, because with Li chemistry there is a Battery Management System that protects the cells and balances voltages between cells. A single 24V battery is better because the BMS has access to all 8 cells rather than 2 x 12V batteries with separate BMS.

LiFePO4 batteries will have slightly different charging voltage and current requirements. LFP does not need to be equalized and batt temp coefficient can be set to zero. Float charging is treated a little differently depending on your use case.

 

[bluefin99]

Thanks very much...hard to find a Schneider person to answer this :-( Hard to find 24V in bigger aH so I'll now be ordering 2 ea 12v 280 aH batteries. Im presuming that they will come with instructions for settings on the 4024 remote panel ( eg. 14.4 max voltage ).

 

[400bird]

If you're going to ignore the recommendation to go with 24 volt batteries, the second best option is to get a battery balancer to keep the two 12v batteries at the same voltage and hope that it keeps the cells in each independent battery balanced. It's a bandaid, but better than nothing.

Battery balancer:

Victron Battery Balancer |Current Connected

The Victron Battery Balancer equalizes the state of charge of series-connected 12V batteries, or of several parallel strings of series-connected batteries.

www.currentconnected.com

While we're at it, they've got good 24v batteries:

SOK 24V 100Ah LiFePO4 Solar Battery | Current Connected

Experience reliable and powerful energy storage with the SOK 24V 100Ah Battery. It's built to last and packed with features!

www.currentconnected.com

 

[alcook62]

Thanks very much...hard to find a Schneider person to answer this :-( Hard to find 24V in bigger aH so I'll now be ordering 2 ea 12v 280 aH batteries. Im presuming that they will come with instructions for settings on the 4024 remote panel ( eg. 14.4 max voltage ).

I have a Schneider SW 4024 inverter that has been charging my 510ah LiFePO4 battery bank for three years. You can set your preferred parameters by entering them via the Conext SCP in the Advanced Settings menu.
I'd like to also second the previous recommendations to avoid the series-connected 12-volt batteries. Get a couple (or more) of the 24-volt batteries and avoid the inevitable balance issue between the series-connected 12-volt setup.

 

[alcook62]

Im presuming that they will come with instructions for settings on the 4024 remote panel ( eg. 14.4 max voltage ).

Just caught this. Once series-connected, you've created a 24-volt battery and must set your charging parameters appropriately. 14.4 volts will not charge a 24-volt battery consisting of two 12-volt batteries series connected.