Confused about charge controller and battery discharge

[Jaycee007]

Hello, this is my first post here. I have been reading from the forums for a while and I am amazed by the wealth of knowledge here. I have a few questions about my system that I was able to find information on but I also saw conflicting information somewhere so I am confused. I want my inverter to stop pulling power from the batteries when they are around maybe 50% to 60% or whatever is best, I just dont want to discharge them beyond what is reasonable. I saw on some sites that 50% is around 12.2 volts (not sure if im allowed to post that link here). And then others said 10.7 volts. My charge controller has 10.7 programmed into it by the guy who installed so which one is correct? I have a 6 volt system with the batteries wired in series to make 12 volts, the batteries are trojan t-105.

Another thing I was wondering was what is controlling when the power shuts off because the charge controller comes before the batteries in the chain and the inverter comes after the batteries so is the charge controller really controlling when the power stops flowing from the batteries or is it the inverter? Thanks for any assistance.

[organic farmer]

My system has a Low-Battery-Cut-Off preset. I can determine the v_oc that I want it to shut down at.

[NEOH]

Hello, this is my first post here. I have been reading from the forums for a while and I am amazed by the wealth of knowledge here. I have a few questions about my system that I was able to find information on but I also saw conflicting information somewhere so I am confused. I want my inverter to stop pulling power from the batteries when they are around maybe 50% to 60% or whatever is best, I just dont want to discharge them beyond what is reasonable. I saw on some sites that 50% is around 12.2 volts (not sure if im allowed to post that link here). And then others said 10.7 volts. My charge controller has 10.7 programmed into it by the guy who installed so which one is correct? I have a 6 volt system with the batteries wired in series to make 12 volts, the batteries are trojan t-105.

Another thing I was wondering was what is controlling when the power shuts off because the charge controller comes before the batteries in the chain and the inverter comes after the batteries so is the charge controller really controlling when the power stops flowing from the batteries or is it the inverter? Thanks for any assistance.

I am having a very hard time understanding your description "comes before the batteries ... comes after the batteries". HUH?

Is your charge controller connected directly to the battery bank?
Is your inverter connected directly to the battery bank?

If both answers are yes, then there is no "before" or "after" - both are equally connected to the battery bank.
Next, you need to do some research regarding "Resting Voltage" vs "Under-Load Voltage" - these voltages are different.

The "Resting Voltage" that equals 50% SOC is approx 12.1 Volts.
The "Under-Load Voltage" that equals 50% SOC varies based upon the size of the battery and the amperage flowing from the battery through the load.

The "Under-Load Voltage" that represents 50% SOC will be lower than 12.1 volts - due to the load being present.

Your Inverter should have a Cut-off Voltage, not your Charge Controller.
So now I do not understand this: "... My charge controller has 10.7 programmed ..."
Exactly, what does your Charge Controller do at 10.7 volts?

You can measure the S.G. (Specific Gravity) of the electrolyte to know better when your batteries are at 50% SOC - even under load.
The "Resting Voltage" is a very good estimate of the State of Charge
The "Under-Load Voltage" is not very accurate but it is all you can use to shut-down your inverter while under load.

If the load is light, then the "Under-Load Voltage" at 50% SOC will be just below 12.1 Volts.
If the load is mild, then the "Under-Load Voltage" at 50% SOC might be 11.5 Volts.
If the load is heavy, then the "Under-Load Voltage" at 50% SOC might be 11.0 Vols or lower !