Switch to LIFePO4?
I have a trio of Rolls Surrette FS210 wet cell batteries that give me about 315 AH of usable capacity. My big concern is weight, the total is 400 lbs in my from compartment of the 5er, and I think tha...
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Update: received the batteries on Thursday. 2 very well packed boxes containing 2 batteries each (30 lbs per battery). Pulled them out and inspected, BMS on top, showing charged at 100% at 13.4 v. So in theory I should get up to 320 useable AH if I don’t go below 80% discharge. This is equivalent to what I had with the Rolls batteries (3x 210 AH @ 50%.... but 400 lbs vs 120!).
Next step is to remove the old inverter and batteries (that will be a bear) and install the Samlex 3000 W inverter charger.
The Samlex has an input to feed up to 50A of solar, is there are meaningful reason to do this? I currently have 2 Victron MPPT controllers direct to battery bus bars (1 is 50A the other is 30A, each controlling different arrays - the 30A on a 12V legacy array giving 650W, the 50A at 30V with a 280W single panel)? The Victron controllers can be configured for LIFePO4, so unless there’s an advantage I don’t grasp I’d keep that as is.
Here are the settings the battery company owner sent me for the batteries:
Settings Recommended.
3 STAGE CHARGING MODE, you do not want the 4th stage, equalization.
Bulk current = 60 - 100A, 80A is 0.2C which is the standard charge current for a 400Ah bank. Adjust to preference. If you are looking for quick charging you can boost it up. If you are looking to preserve the batteries as much as possible you can lower it. 140A MAX (.35C)
Absorption Voltage = 14V - Start here. I set this low because there is very little benefit of charging to above 14V. Also, the absorption time on this charger is not directly configurable. Generally I would like to see the absorption time set to 0. This will be a safe place to start. We can adjust later if needed. Please monitor the voltage at the beginning and end of the absorption stage and the time it takes.
Floating Voltage = 13V, You want this as low as possible. Turn off if possible.
Temperature Compensate = OFF or standard
Batt Low Voltage = 12V or as desired. If you find it kicks the batteries out at 12V under heavy current draw you can lower it. Do not set this below 11V.
Reset Voltage = 12V
Batt Over Volt = 14.2V, If you raise the Absorption Voltage this should be raised as well. 14.6V MAX. The batteries will cut out internally at this voltage.
Charge Mode = 3 stage
Please note
I recommend disconnecting all charge sources from the battery bank when you are not using the system for longer periods. It is ideal to rest the battery bank at 50 - 80% charge. Do not leave the batteries fully charged for more than a couple days. Charge before use. These do not require float charging. I have set the float voltage to as low as possible which has been proven to be safe for these batteries. Still avoid floating if at all possible.
Next step is to remove the old inverter and batteries (that will be a bear) and install the Samlex 3000 W inverter charger.
The Samlex has an input to feed up to 50A of solar, is there are meaningful reason to do this? I currently have 2 Victron MPPT controllers direct to battery bus bars (1 is 50A the other is 30A, each controlling different arrays - the 30A on a 12V legacy array giving 650W, the 50A at 30V with a 280W single panel)? The Victron controllers can be configured for LIFePO4, so unless there’s an advantage I don’t grasp I’d keep that as is.
Here are the settings the battery company owner sent me for the batteries:
Settings Recommended.
3 STAGE CHARGING MODE, you do not want the 4th stage, equalization.
Bulk current = 60 - 100A, 80A is 0.2C which is the standard charge current for a 400Ah bank. Adjust to preference. If you are looking for quick charging you can boost it up. If you are looking to preserve the batteries as much as possible you can lower it. 140A MAX (.35C)
Absorption Voltage = 14V - Start here. I set this low because there is very little benefit of charging to above 14V. Also, the absorption time on this charger is not directly configurable. Generally I would like to see the absorption time set to 0. This will be a safe place to start. We can adjust later if needed. Please monitor the voltage at the beginning and end of the absorption stage and the time it takes.
Floating Voltage = 13V, You want this as low as possible. Turn off if possible.
Temperature Compensate = OFF or standard
Batt Low Voltage = 12V or as desired. If you find it kicks the batteries out at 12V under heavy current draw you can lower it. Do not set this below 11V.
Reset Voltage = 12V
Batt Over Volt = 14.2V, If you raise the Absorption Voltage this should be raised as well. 14.6V MAX. The batteries will cut out internally at this voltage.
Charge Mode = 3 stage
Please note
I recommend disconnecting all charge sources from the battery bank when you are not using the system for longer periods. It is ideal to rest the battery bank at 50 - 80% charge. Do not leave the batteries fully charged for more than a couple days. Charge before use. These do not require float charging. I have set the float voltage to as low as possible which has been proven to be safe for these batteries. Still avoid floating if at all possible.
