I live in a part of the world where powercuts are pretty frequent. 1 per day is normal. They last between 1 and 8 hours. A day without powercuts feels like a special occasion.
My machine is powered by a desktop ups which is terrible. It is only supposed to power everything for a few minutes to shutdown safely. But it is cheap and I don’t know much about other affordable alternatives.
How do you folks who self host at home deal with powercuts? Any recommendations? 8 hours of uptime from a ups sounds almost impossible or totally unaffordable to me.
some 2nd hand car batteries + 12-230v converter are probably the cheapest option
Forgive me if I’m wrong, but auto batteries aren’t meant for deep discharge. UPS’s use a specific type of battery that is meant for it.
Using auto batteries in this situation would likely end up in them dying after a few months.
“Deep cycle” batteries are the best of the lead-acids for the task. But they are still obsolete and you should source lithium if at all practical.
However if power interruptions are short, loads are low or you have an external power source like solar or wind, inferior batteries can do the job.
I use a bunch of old car batteries at my house for my battery bank. It’s more of a big capacitor, but it’s almost always sunny here and kW of solar are pouring in.
My critical equipment i.e. starlink, home and farm automation and monitoring, cell booster and HMI/SCADA only take a couple hundred watts, so no big deal. Most of the solar power goes to keeping the freezers cold.
Thanks for your insight. You seem to have some experience.
I’m currently researching a solar hybrid power system in India and am going through different battery types. We have used deep-cycle lead-acid batteries with a regular UPS and I’m familiar with their lifesoan.
Do lifepo4s last longer? I’m only seeing marginally longer lifespans. I’m also concerned about safety. I’m quite scared of regular lithiums and have read that lifepo4s are more hardy.
What about maintenance? Anything else I need to know about them?
Car batteries are cheap storage if you very rarely discharge them. You get many years if you are only using the top 80% or so of their voltage range, but if you discharge them to 50%, you only get a few hundred cycles, and if you discharge to 0%, you get dozens, if that. “Deep cycle” batteries have the same characteristic, but tend to give you more amp-ours before you hit those thresholds.
Good Lifepo4 batteries could last up to 10 years with daily full discharges. They are quite amazing in that respect. They are also likely safer than even lead acid -which need to be vented properly to avoid hydrogen gas buildup. They don’t get thermal runaway like lipos, but the cells are very much capable of producing enough current for electrical fires, so you want ones that are built properly. Maintenance is pretty much just “don’t ever charge it if it’s frozen.”
I didn’t know that deep-discharge batteries also had the same characteristics, TIL, and it makes sense based on my experience with them!
As the other commenter said, it’s all about depth of discharge. A 10kWh Lifepo4 bank gets you almost 10kWh every time while you should treat a 10kWh lead-acid bank as if it was a 2kWh bank for any sort of decent life, with deep discharges being limited to emergency situations.
All lithium chemistries are practically maintenance free while you are probably familiar with water level monitoring and equalization of lead acid.
Note that all site built lithium banks MUST have a balance mechanism as this is their “automated maintenance”. Without balancing on every charge, lithium cells will be rapidly destroyed.
Good points to note, thank you! I would have taken the balancing circuit for granted, but it doesn’t hurt to double-check with vendors.