Hi. I built/am improving a small system with 12V 230ah LFE / 2000 watt Voltworks PSW inverter/ Victron smart 15A charger/ Victron Smartsolar 75/15 SCC and only 100 watts panel (will add more eventually) Also I have a $40 shunt that is yet to be installed.
I have a few goals with this in order of priority:
1) power my fridge and some electronics during frequent power outages in Mexico
2) condition power to fridge to get voltage up in a double conversion UPS sorta way
3) make use of any solar I'm capturing
Battery runs for maybe 35 hours by itself, and since I don't have much solar panel, it will not keep up if the power is out for days, depends on the solar gain and amount of time grid is down. Last hurricane power was out for 3 days but normally it's a half day or so.
I have been using the basic setup for a few months to run the fridge and not had issues except once when I was fiddling with it. Won't get into that.
Problem is - I'm leaving for a couple months later this summer. I would like to leave this new system in the loop but am concerned about depending 100% on the battery + inverter. For one thing, the inverter will not come back on automatically if battery drains low enough to trigger it's fixed 11v disconnect. That 11v could be under fridge motor startup before battery was actually too drained. I could end up in worse trouble if power goes off after a big storm, low solar and the fridge draws it down until inverter disconnects then nothing even when grid is back.
I saw the MOES ATS and thought it could be perfect but looking harder I see that not only could I end up with the inverter off situation but also the chance of back-feeding and burning out my inverter. And it's a device that is reported to fail often enough.
So I looking at a simpler but safer transfer switch that detects V in the primary source and goes to secondary source (grid) if primary is down. I have not looked hard yet, but something like this: Mini Dual Power Automatic Transfer Switches
That should more safely keep me on the inverter unless and until battery gets low. At that point, either due to a failed (or shut down) inverter, BMS or drained battery it will go to grid. Assuming the ATS does not fail, I will have the grid connected no matter what happens to my battery system...I think. If the battery/inverter system is out AND the grid is down, need to verify that it will connect to the grid once that's back up.
Then, to avoid having the system drain my battery down to the inverter's LVD nor depend on the BMS LVD (which would also leave the inverter off ) I am thinking to manage a relay that interrupts after the inverter to drop out the major load on the battery but keep the inverter on with battery power. Yes it will slowly drain the battery but much slower, giving time for power to come back on or the sun to bring up the battery.
So, I install a relay that can close a 20 amp AC circuit with 12v on actuator side. NO. Dime a dozen, right? I could then trigger that off the load output from my Victron SCC giving me an adjustable LVD after the inverter but before the ATS. I could also trigger other relays with same signal, such as an NC from grid to ATS if that made any sense as a failsafe.
Anybody see a problem with this ? It's a cheap solution and seems least likely to leave me without power once the grid is up, won't ever back-feed my inverter (correct?) nor depend on the reliablity of something complex like the MOES. I feel far better trusting my LVD to Victron and managing the actual amps with a dumb relay feeding a fairly dumb ATS.
Does that ATS look good or which do you guys like without getting spendy ? Max current is 20amps though it will actually operate <10. Low budget system or I would have just bought a multiplus.
Thanks
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I have a few goals with this in order of priority:
1) power my fridge and some electronics during frequent power outages in Mexico
2) condition power to fridge to get voltage up in a double conversion UPS sorta way
3) make use of any solar I'm capturing
Battery runs for maybe 35 hours by itself, and since I don't have much solar panel, it will not keep up if the power is out for days, depends on the solar gain and amount of time grid is down. Last hurricane power was out for 3 days but normally it's a half day or so.
I have been using the basic setup for a few months to run the fridge and not had issues except once when I was fiddling with it. Won't get into that.
Problem is - I'm leaving for a couple months later this summer. I would like to leave this new system in the loop but am concerned about depending 100% on the battery + inverter. For one thing, the inverter will not come back on automatically if battery drains low enough to trigger it's fixed 11v disconnect. That 11v could be under fridge motor startup before battery was actually too drained. I could end up in worse trouble if power goes off after a big storm, low solar and the fridge draws it down until inverter disconnects then nothing even when grid is back.
I saw the MOES ATS and thought it could be perfect but looking harder I see that not only could I end up with the inverter off situation but also the chance of back-feeding and burning out my inverter. And it's a device that is reported to fail often enough.
So I looking at a simpler but safer transfer switch that detects V in the primary source and goes to secondary source (grid) if primary is down. I have not looked hard yet, but something like this: Mini Dual Power Automatic Transfer Switches
That should more safely keep me on the inverter unless and until battery gets low. At that point, either due to a failed (or shut down) inverter, BMS or drained battery it will go to grid. Assuming the ATS does not fail, I will have the grid connected no matter what happens to my battery system...I think. If the battery/inverter system is out AND the grid is down, need to verify that it will connect to the grid once that's back up.
Then, to avoid having the system drain my battery down to the inverter's LVD nor depend on the BMS LVD (which would also leave the inverter off ) I am thinking to manage a relay that interrupts after the inverter to drop out the major load on the battery but keep the inverter on with battery power. Yes it will slowly drain the battery but much slower, giving time for power to come back on or the sun to bring up the battery.
So, I install a relay that can close a 20 amp AC circuit with 12v on actuator side. NO. Dime a dozen, right? I could then trigger that off the load output from my Victron SCC giving me an adjustable LVD after the inverter but before the ATS. I could also trigger other relays with same signal, such as an NC from grid to ATS if that made any sense as a failsafe.
Anybody see a problem with this ? It's a cheap solution and seems least likely to leave me without power once the grid is up, won't ever back-feed my inverter (correct?) nor depend on the reliablity of something complex like the MOES. I feel far better trusting my LVD to Victron and managing the actual amps with a dumb relay feeding a fairly dumb ATS.
Does that ATS look good or which do you guys like without getting spendy ? Max current is 20amps though it will actually operate <10. Low budget system or I would have just bought a multiplus.
Thanks
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