Originally Posted by
Bear
I wonder how much power they draw when they're plugged in but not actually being used.
Also wonder how long they'll hold a charge if they're left fully charged but unplugged, and just stored away
How long they will hold a charge not plugged in is totally dependent on the batteries. Some batteries have a better shelf life. It's just like any electrical item that runs off batteries, if they are not recharged, over time the battery will die. This is a common reason that a ups is thrown away. I've never seen one that was actually broken. People let them sit and after a few years the batter goes bad. I use a small solar panel to keep them charged but after a few years, the batteries just wear out. Ironically, the more you use and charge the batteries the longer they last.
There are a few basic things that you will need to ask:
1. How big is the ups? A 1500w ups will put out 1500 watts in AC sine wave.
2. What are you going to plug into the ups. You can plug in as much as you want to as long as you don't exceed the ups' capabilities (ie. 1500 watts)
3. What is the draw off of the batteries. The specs of the UPS will tell you what the amp draw is.
4. How long do you want to run things off of the UPS? This will be used in the battery decision. If the ups is drawing 10 amps for 1500 watts a 12ah (amp hour) batter will last you 1 hour (a 12ah battery will put out 1 amp for 12 hours, 2 amps for 6 hours, 6 amps for 2 hours, ect...). If you are using less than 1500w the battery will last longer.
Once you figure these things out you can mathematically figure out what you want to do. The small batteries that come with a UPS will not allow the UPS to run for a very long time. You can very easily purchase larger batteries that will last longer cheap off
ebay.
The easiest way to get started is to begin reading solar power websites. They will have all the formulas you need to figure this out as well as how things should be hooked up. I personally run my off of 2 6v batteries rather than a single 12 v. There is NOTHING different between what you have and what people use to hook solar power up to a home or an inverter system to a boat. You have a UPS which is an inverter, built in charger, and batteries.
I would just play around with a few of them then when you find a deal on ebay add a solar panel.
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