Can I use ups by charging it via a 45w solar panel I made

ups is a 300w with 7amph battery and it is 110v
charging can I use regular 12v 4.5amp dc?
and disconnect the charger because it is 110 but I will be using in 220v country?

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It'll probably work.  The solar panel needs to put out more than 12V to charge the battery, though.  A full charge will need about 13.8 to 14.4 volts, and there should be an isolation diode between the panel and battery, so that's another volt.   Some current limiting may be necessary, since a 7AH battery probably doesn't want to be charged at more than 1.25 amps or so.  Find the battery model number, and look up the charging specs online.

Make sure the UPS has a way to manually start the inverter.  With some APC Back-UPS, that can be done by toggling the test switch in the down direction after switching on.  On other models, you may have to find a schematic or reverse engineer them to find a way to start the inverter manually.

You might be better off to just pull the battery and use a normal inverter.  Those are pretty cheap now if you catch the right sale.  At least around here (I got a 75VA one for $10, and a 300VA one for about $25).  But, the UPS may have better (and safer) isolation - small inverters often don't have a "neutral" neutral line (it's the same voltage swing as the line output, but opposite phase).
celalboz (author) 7 years ago
I agree with all above. My goal was to use the UPS in some way because I have it and the SLA is died, I was hoping to use the charge regulator portion in it. Since it is charging its Sla with 12v with what ever amp. and the Brick inside providing 12dc to it sounded like a solar charge controller, I will measure it live to see what is it putting out to the SLA and is it wort it if not I use the componenets out of it to build a Solar Charge controller if I can find a circuit,  I love to build and I have fat bank account...
thanks for prompt reply..

Maybe some one knows the answer. I want to make a DIY ups, to run a computer when the power goes out. My question is Will a "pure wave sine inverter" turn on INSTANT. I have the solar panels and batteries ,and I built a Switch with realys that will switch a plug outlet from 120vac to the inverter and that will feed the computer. Do ALL pure sine wave interverters go /turn on with Instant power. So that it would not have a few second power loss to the compurer. tks
Using capacitors might be simpler. But that wouldn't be cheap.
celalboz (author) 7 years ago
110v Inverter: I bought an inverter 600w but some says even if I don't draw 600w out of it,  say I draw 100w out of it, because it is big it will draw many aps from my battery unnecessarily,
Is it  better to buy a 100w for better performance for a say 90w load?
much obliged..