Home UPS - is it viable?

[ik9000]

Anyone have any idea if it's practical to have home UPS for key items - fridge, freezer, server switches, modems + computers? Is it as expensive as I fear it would be?

[Jowsey]

I think I read somewhere that old hyrbid car/electric car batteries were being refurbished and installed in places that have unreliable power. Could be an avenue of research?

[peterb]

Anyone have any idea if it's practical to have home UPS for key items - fridge, freezer, server switches, modems + computers? Is it as expensive as I fear it would be?

Yes and yes!

There is a device designed to be used with solar installations that charges the batteries by day, and then discharges them through an inverter at night to reduce the reliance on grid supplies.

However.....

The cost of the basic inverter is around £2,700 - which isn't too bad, but it requires two lithium ion batteries at around £1,000 each! I worked out the payback time is about 12 years, roughly the service life of the batteries.

Prices will fall in time, but I don't think it is viable yet for domestic use.

If you want a house UPS for things like fridges and so on because of unreliable supplies, you are better off buying a small generator. Either one with electronic regulation so it gives a smoother and better regulated supply for televisions and computers, (although a standard type works well enough) or feed it into a standard UPS for a TV/ computer.)

That will give you long running times for fridges and freezers.

Depends on how unreliable your mains supply is.

[GoNz0]

Anyone have any idea if it's practical to have home UPS for key items - fridge, freezer, server switches, modems + computers? Is it as expensive as I fear it would be?

Until I was moved into the dining room my 3rd bedroom's power was fed through a APC Smart-UPS 2200, this included the central heating as it was in the cupboard.


So yes if you have the money and don't mind the noise if it located within earshot a UPS is a great idea for PC equipment.

As for fridges and freezers it isn't a good idea as a UPS doesn't last long, mines huge but is designed to hold 2200w for about 15 minutes so pointless for the average fridge as the power will be on long before the temp raises.

I fed mine through to the heating as a loss of power at night would have been with next to no load so it would have given us time to have a shower each in the morning and go to work.

Now it isn't up the loft I swapped the fan to a lower more silent version as it is pure overkill for home use

Or do as Peter said, buy a small genny and hook it up a UPS so you have time to power it up, some can power up when the mains are down but it will cost a lot more.

[smargh]

Don't attach a UPS to a fridge/freezer. UPSes hate motors, and the compressor in fridges/freezers needs a huge inrush current (and a voltage which doesn't droop) to start up. If you do try a UPS, you may damage the UPS itself, or alternatively you could get an overload alarm, even if you think the UPS is rated for enough wattage.

So, same as what everyone else has said: get a proper genny. The cheap ones might not be able to maintain a steady voltage, and the frequency can drift, which electronic equipment really doesn't like. Get an appropriately sized Honda (with "inverter" tech).

You can do whole-house UPS systems.... but unless you're a qualified skilled electrician you'll just end up blowing things up & burning things down: https://www.youtube.com/watch?v=ka0MfipmdBw

[peterb]

That was an interesting video, although it might be more cost effective to swap all his lights for LEDs (but I don't know when it was made)

You can use lead acid cells with the system I described, but the service life is shorter, (charge/discharge cycles) and the energy density is lower, so the long term cost saving is minimal.

The main nighttime load in my house are the fridge and freezer, an in theory the freezer could be switched off at night as over a few hours the food wouldn't thaw if the door is kept closed, but then you would use more energy during the day (ok if you have solar and it is sunny) but not really worth the risk or faff.

[DDY]

That was an interesting video, although it might be more cost effective to swap all his lights for LEDs (but I don't know when it was made)

You can use lead acid cells with the system I described, but the service life is shorter, (charge/discharge cycles) and the energy density is lower, so the long term cost saving is minimal.

The main nighttime load in my house are the fridge and freezer, an in theory the freezer could be switched off at night as over a few hours the food wouldn't thaw if the door is kept closed, but then you would use more energy during the day (ok if you have solar and it is sunny) but not really worth the risk or faff.

Having watched a few of Photonicinduction's videos - the guy who made the video above, he has already retired a whopper of a lead acid battery from that system and swapped all his lights over to LED.

I thought about having a house-wide electricity backup system but dismissed it, considering that my UPS has only recorded five power outages last three years with the worst lasting a whopping 15 minutes, truly a first world disaster. And it's really expensive...

[pwrslave]

Anyone have any idea if it's practical to have home UPS for key items - fridge, freezer, server switches, modems + computers? Is it as expensive as I fear it would be?

UPS for computers is a good idea, but I don't really get the freezer part? A normal freezer stays frozen for hours in the case of power outage...