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)?
I have a few cyber power 1000W/1500 VA units. They go on sale for under $150 now and then. Best price/power ratio I’ve found. The battery in one has lasted at least 6 years, other is going strong for at least 2. They’re big enough to power my 8 bay NAS for a couple hours. I don’t recommend DYI for a UPS, too unreliable.
Not only is a DIY UPS unreliable, but it could be potentially dangerous unless you are an electrician, an electrical engineer, or somebody that has extensive knowledge of both the engineering side and safety side. How many CyberPower units do you have? It’s impressive that you have enough UPS power to run a NAS for that long.
I have 3 - but I get that runtime out of one of them. Depends on load, but idle the nas doesn’t draw too much.
Where did you purchase? Camelcamelcamel shows those sub-$150 price drops on that capacity might be a couple years old, too. :-)
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 don’t have anything to add in terms of solutions, but I think it’s worth trying to understand why your batteries only last 1 or 2 years.
If it’s because they’re too low capacity for your needs and you’re deep draining discharging them often, then you might be able to save money in the long term by getting a larger, more expensive UPS. If the environment where they operate is harsh (eg: too hot), maybe the fix is actually air con or something like that. And so on.
Batteries can last a long time, but you need to avoid the extremes: temperatures, state of charge, charging cycles, etc.
No. For most (if not all) batteries the recommendation is to avoid discharging them too much.
Having a larger battery helps here because you won’t go as deep. On a larger UPS, maybe you’ll be at 30% when the power returns instead of being at 5%. On a phone, it may reduce the number of charging cycles because you no longer need to charge during the day or have to go too deep. On EVs, a larger battery means that you won’t have to fast charge as much during trips and that you won’t have to charge it to 90% to reach the next charger or arrive with a very low state of charge.
Larger batteries also allow devices to age better. If I get a phone that barely lasts me a day, I’ll probably have to replace the battery or carry a power bank around after a while. On the other hand, if I always end the day with 20-30% left, I’ll only have problems after losing ~20% of capacity. It’s the same with a UPS. If we find ourselves going down to 5% when it’s new, then 2 or 3 years later that USP won’t be enough for our load/outages and will shutdown before power returns.
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.
