I’m tired of buying a new 12 V battery every 1-2 years. I have about 4 small (rated ~ 300 W [not VA]) UPSes with 7 Ah, 12 V, maintenance free batteries.
I’m thinking about replacing them with one, powerful unit. But the more powerful the unit, the more it costs - non-linear.
Do you have experience with some DIY solutions? Like 12V DC to 230V AC inverter, battery charger, some UPS controller (simple relay?)?
Or maybe you have some other idea that is cheap(ish)?
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If you have three phase power and lose power on one then batteries come in handy. Otherwise a nice generator helps. But OP will just be trading swapping one battery for a tray of batteries instead.
The ups comes into play when you suddenly don’t have mains.
Hence, the name UPS, ie uninteruptable power supply.
if you’re running batteries down often enough to need battery replacements that frequently, you may be going ‘too cheap’ (poor quality and/or not enough capacity) to begin with, and would need an upgrade not another ‘cheap’ solution.
I built a homemade one. 2.4kwh of capacity.
Should be good for a few decades easily.
Wouldn’t call it cheap. But, it will be around for 15 or 20 years.
https://xtremeownage.com/2021/06/12/portable-2-4kwh-power-supply-ups/
Man. That AIMS low frequency inverter is nice.
I actually bought one of those cheaper Chinese pure sine wave inverters, but found that they don’t run motors/power tools that well. The surge current demand just exceeds anything they can provide. They’re great for resistive loads like PCs/LEDs/Hotplates, but if you wanted to run a table saw or something the AIMS is the only way.
Cheaper or not, isn’t a huge factor.
My really expensive sol-ark 12k cannot start my 110v air-compressor.
The issue is, the rated L.R.A. ie, locked rotor amps, how much current it takes to get it started.
My A/C motor, for example, uses around 20 amps @ 240v when running, ie ~5,000w. However, its L.R.A, is 112.0 amps @ 220v, ie- (24,640 watts). Which is more than the peak load my 12k inverter can handle. So- if you tried to start it on the inverter, well, it doesn’t work.
https://static.xtremeownage.com/blog/2023/off-grid-ac/
The same principle applies to anything with a motor.
You have to evaluate the L.R.A. Remember, if you have say, a 5,000watt RMS inverter, which can handle a 10k peak- its not going to be able to start something that has a 14,000 startup draw.
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Wait. Should I be deep draining?
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Yeah that’s good then.
I get about 60m runtime on my setup and it only cycles 10-20% max.
Already had to change the battery early and wondered if that was why.
I doubt there is a much better solution, the huge rack mounted UPS are just tons of 12v batteries wired together. I would question why your batteries are dieing so frequently, I expect to get 5+ years out of mine with light use.
I wonder why they’re only lasting 1-2 years. How often do they kick in in your area?
DIY is going to be more expensive, and much less safe.
Others have given the direct answer of “no”. Cheap is relative, so here are some options that assume a higher value of “cheap”.
DIY solar panels and DIY flywheel generator.
Professional solar panels on your dwelling and professional whole house battery storage. (Fix the issue by fixing a larger issue.)
Buy an electric car that can power the equipment. A Ford Lightning (there are other choices) in the garage, that never moves, will solve the issue of swapping batteries. Check junkyards for a used one.
Move closer to a power plant, while also ensuring a minimum power line distance.
Move closer to something with a very high up time requirement. (A hospital may have generators, but they may also have a requirement for their power to stay up nearly always.)
Use AWS or co-hosting to make power not your issue.
Are you really suggesting someone buy a used Ford Lightning to use as an alternative to a DIY UPS and never drive? The DIY UPS sounds 100x more practical.
No. I do not suggest anyone do any of these.
