Hi,
So, I have 2 strings of 12 volt LiFePO4 batteries x 4 to make 48 volts, 100 AH each. This is working well but I now realize, again, I went in the wrong direction. So I want to pivot to cells. The cells I'm thinking about getting are 314 AH. If I understand correctly, I can't just add that bank to my 2 existing strings because they would only drain down until the 100 AH batteries are depleted. Then all batteries go off-line? Even if they don't all go off-line, the 314 AH could start trying to charge the 100 AH and then I would have a mess?
If that is correct, is there any hardware and/or software that would allow me to automatically turn on the 100 AH batteries (assuming I have them disconnected totally from the system via a programmable relay/switch) when the 314 AH batteries get down to 30% SOC? Then they could all ride down to 5% SOC together? Thus spreading the load of the last 30% SOC?
Of course, then, I would have to disconnect the 100 AH batteries again from the system when they get back up to 95% or so SOC. So that the 314 AH batteries can fully charge. Because, if not, then they will signal the charge controller that they are full and it will go into absorption mode? Leaving the 314 AH batteries not fully charged?
The other option would be to have the 100 AH batteries kick in when the 314 AH batteries are near depleted using a generator lead in. That seems easier on the discharge, but I can't think of an easy way to charge the 100 AH batteries again using that approach.
First, is my understanding correct?
Second, is this a good way to get use out of my existing batteries? Should I even be trying to do this?
Third, does something exist out there that does this already? I thought about using something like this: https://www.getlithium.com/29_Perfect_Switch_Battery_Isolators.html
So, I have 2 strings of 12 volt LiFePO4 batteries x 4 to make 48 volts, 100 AH each. This is working well but I now realize, again, I went in the wrong direction. So I want to pivot to cells. The cells I'm thinking about getting are 314 AH. If I understand correctly, I can't just add that bank to my 2 existing strings because they would only drain down until the 100 AH batteries are depleted. Then all batteries go off-line? Even if they don't all go off-line, the 314 AH could start trying to charge the 100 AH and then I would have a mess?
If that is correct, is there any hardware and/or software that would allow me to automatically turn on the 100 AH batteries (assuming I have them disconnected totally from the system via a programmable relay/switch) when the 314 AH batteries get down to 30% SOC? Then they could all ride down to 5% SOC together? Thus spreading the load of the last 30% SOC?
Of course, then, I would have to disconnect the 100 AH batteries again from the system when they get back up to 95% or so SOC. So that the 314 AH batteries can fully charge. Because, if not, then they will signal the charge controller that they are full and it will go into absorption mode? Leaving the 314 AH batteries not fully charged?
The other option would be to have the 100 AH batteries kick in when the 314 AH batteries are near depleted using a generator lead in. That seems easier on the discharge, but I can't think of an easy way to charge the 100 AH batteries again using that approach.
First, is my understanding correct?
Second, is this a good way to get use out of my existing batteries? Should I even be trying to do this?
Third, does something exist out there that does this already? I thought about using something like this: https://www.getlithium.com/29_Perfect_Switch_Battery_Isolators.html
