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+--- Thread: recommended 12v timer switch to toggle inverter? (/showthread.php?tid=19077)
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recommended 12v timer switch to toggle inverter? - terracore - 01-04-2018
I'm looking for a timer switch to go between a 12v battery and an inverter to turn the inverter off at night and back on during the day. I've seen several on various online sites but was wondering if anybody here had specific recommendations? Prefer one with no or little parasitic losses.
ETA: "?"
RE: recommended 12v timer switch to toggle inverter? - randomq - 01-04-2018
I use a relay, with my charge controller's "load" timer activating it. (The load port can't handle anything with an in-rush or high amperage on its own.)
If just using a battery, no experience there.
RE: recommended 12v timer switch to toggle inverter? - kalakoa - 01-04-2018
Flexcharge PRGTMR12V -- not cheap, but high quality, I've used them both ways (inverter control or switched outlet with 110VAC on the relay side).
Available on Amazon or eBay, but I get mine from www.solarseller.com.
RE: recommended 12v timer switch to toggle inverter? - Durian Fiend - 01-05-2018
quote:
Originally posted by terracore
I'm looking for a timer switch to go between a 12v battery and an inverter to turn the inverter off at night and back on during the day. I've seen several on various online sites but was wondering if anybody here had specific recommendations? Prefer one with no or little parasitic losses.
ETA: "?"
Tired of doing it manually? Serious question-I'm wondering why.
RE: recommended 12v timer switch to toggle inverter? - kalakoa - 01-05-2018
Conventional (110VAC) fridge is the highest draw; cycling it off at night makes a big difference in a small off-grid system.
Switching the DC side of the inverter is impractical due to the current involved; if you could find a relay big enough to handle the load, the draw from its coil would easily be more than the standby current for the inverter.
I used an inverter with a "remote on/off switch" wired to the timer. Works great.
Later I rewired the timer to create a switched outlet for the fridge, and just left the inverter on all night; the standby draw is negligible, and this way the TV would still work when I couldn't sleep.
Standby current on the Flexcharge is something like 3mA.
RE: recommended 12v timer switch to toggle inverter? - terracore - 01-05-2018
"Tired of doing it manually? Serious question-I'm wondering why."
Inverters draw DC current even when there is no AC load. Looking to end that draw during the hours there will never be any AC load.
RE: recommended 12v timer switch to toggle inverter? - kalakoa - 01-05-2018
end that draw during the hours there will never be any AC load
I used to think that way too. Eventually, the complexity (and power draw) of the workaround is worse than the original loss; by upgrading to a bigger system, I was able to avoid all that micromanagement.
Consider that lead-acid will self-discharge at 5%/month, which is about 0.08% every 12 hours; the 500mA consumed by an "idle" inverter is a rounding error by comparison.
RE: recommended 12v timer switch to toggle inverter? - terracore - 01-06-2018
You bring up a good point, and I might take that into consideration (though my cheap inverter idles at 800mA) but if I'm otherwise looking at hooking up a timer after the inverter anyway, doesn't it make sense to do it before? I guess I need to factor in the draw from the timer compared to what a post-inverter AC appliance timer would be drawing.
RE: recommended 12v timer switch to toggle inverter? - Eric1600 - 01-07-2018
Some inverters will kick on and off if there is a slight load draw, so a timer on the AC side could help unless that is 0.8 A with nothing plugged in.
RE: recommended 12v timer switch to toggle inverter? - kalakoa - 01-07-2018
unless that is 0.8 A with nothing plugged in
Similar principles apply: if a tiny AC load keeps the inverter "active" at less than its "standby" draw, then that AC load is effectively "free".
With my current system, the first 100W of AC load basically doesn't matter -- the inverter will burn that on standby whether or not I use it.