As background, I am a solar newbie, but with the help of this forum and its contributors, i.e. particularly Sun King, Mike and Sun Eagle and a few others, I put together a small system at my shop to run my beer fridge and game freezer, etc. The title of that thread is "Two Free Panels". Long story short, I have two 280W panels, a 45A Morningstar MPPT CC, a 1,740 Samlex inverter and 8 GC2 6V batteries wired in series/parallel for a 24V system. I also have a Samlex 24V 20A charger. I have been experimenting with the system and I can successfully run my loads off grid for 2-3 sunny days before I have to switch to the charger to top off the batts. I do this manually right now and what I'm looking for is a "magic switch" that will monitor the batteries and when they get to some low level (probably between 60-80% SOC, which will probably happen at night unless I get 2-3 cloudy days), kick out the inverter and transfer the load to grid power. Then, when the batts reach a charged state (probably 100% SOC) reverse the process to kick off the grid and switch to the inverter again.
While I have searched the web, unless I get a very sophisticated inverter/charger which includes a transfer switch, I can't find a magic switch to accomplish what I want. I've gotten some tech advice from a tech who told me how I can do this with a battery guard/monitor which, when connected to a relay that is parallel wired with the on/off toggle switch on the inverter to kick out the inverter and then using a transfer switch, the grid power would be utilized. Additionally, the tech said if I wire in another relay that would be connected to the battery guard so that when the battery guard senses the batts are charged again, it would reverse the situation and transfer the load from the grid to the inverter. He even sent me a hand drawn schematic to assist me and recommended the two relays I could use. I ordered the two relays, which were less than $2 each, but after looking at them, I quickly realized that I am in over my head regarding the wiring. For that reason, I am again searching for a "magic switch" that will do what I want to make the entire process automatic. Does anyone know of such an item that would work and cost less than a new compact car?
It has been suggested to me that I could just leave the 3 stage charger on constantly since it will bring the batts up until the float stage and then cycle down to minimum volts until it senses the batts are getting low and then it will kick in to bring the batts back up. Could something as simple as that work or would it end up cooking my batts to leave it on 24/7 or would I just use too much kWh to where it is not economically feasible?
While I have searched the web, unless I get a very sophisticated inverter/charger which includes a transfer switch, I can't find a magic switch to accomplish what I want. I've gotten some tech advice from a tech who told me how I can do this with a battery guard/monitor which, when connected to a relay that is parallel wired with the on/off toggle switch on the inverter to kick out the inverter and then using a transfer switch, the grid power would be utilized. Additionally, the tech said if I wire in another relay that would be connected to the battery guard so that when the battery guard senses the batts are charged again, it would reverse the situation and transfer the load from the grid to the inverter. He even sent me a hand drawn schematic to assist me and recommended the two relays I could use. I ordered the two relays, which were less than $2 each, but after looking at them, I quickly realized that I am in over my head regarding the wiring. For that reason, I am again searching for a "magic switch" that will do what I want to make the entire process automatic. Does anyone know of such an item that would work and cost less than a new compact car?
It has been suggested to me that I could just leave the 3 stage charger on constantly since it will bring the batts up until the float stage and then cycle down to minimum volts until it senses the batts are getting low and then it will kick in to bring the batts back up. Could something as simple as that work or would it end up cooking my batts to leave it on 24/7 or would I just use too much kWh to where it is not economically feasible?
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