After yet another power cut whilst I was out, I think I need to put UPSes on some critical items, namely the fridge and freezer, certain lighting and the heating. The cuts are never more than 4 hours as then I could claim compensation so in theory the Belkin range seem to fit the bill.
Has anybody used these and have comments, or can recommend another brand ?
In that case, you certainly don't need a UPS on the fridge/freezer, in 4h they won't appreciably warm.
As you need to budget for the fridge and freezer motors coming on together, you are looking at somewhere around 3KW surge, which is quite a large one.
What I'd do is to place the UPS on a FCU, and run a low-load circuit from the output (another FCU?).
Now, depending on what you are using for lighting (if you've got 2Kw of lights, or you've gone all energy saving, answers are different), I'd then connect the existing lighting circuit to this, and attach a few
2A sockets to this. The boiler goes into one of the 2A sockets.This then lets you (for example) plug a TV into a 2A socket, if you want to, or to add a generator (add a switch for the UPS to take input from mains or generator.
You may even want to consider if you really want the boiler on the maintained circuit. In 4h you're probably not going to get that cold.
It might be better if you can have a switch to pick between mains and maintained. Unless you've got unlimited battery, you want to be able to ideally start off with as low a load as possible, then add load to it, rather than (for example) coming back 3h into a power cut and finding that all the lights have just about drained the batteries, and you now can't watch TV.
Unfortunately my freezer begs to differ :-) Things got a little frosty.
Good point. Perhaps separate UPSs.
Quite often out so unless the genny comes on automatically it's pointless having one.
We can get a lot of snow here. And of course that's when the power goes off.
Don't think TV comes under essential services :-) If I can keep the house warm, the food cold and me safe by seeing where I'm going I think that will do.
Thanks
Mike
Don't be fooled by the VA rating on these things, I've got a 425VA Belkin which is good for a couple of tens of minutes at 300W loading, nothing much more than that. Only thing I *really* use it for is to protect a video projector from possible power failure; they (well the range I looked at) are only intended for short term, reasonably low-loading backup, to get you out of the sticky-stuff. To continue to run household services I think Ian has the only practicable answer - a generator, out back.
Try some icepacks of salt water that freeze/thaw just above normal freezer temps.
AFAIK if there are still ice crystals in the food (hasn't gone soft) it's OK to refreeze it:
cheers, Pete.
Do you care?
Measure the temperature, and you'll get a much better indication. Frost free freezers will indeed frost up quite rapidly, it doesn't mean much though.
Only if you are damn certain that you'll never have a power cut longer than X hours.
True, but if you're in, then you can turn it on. If you're out, then you can turn it on when you come in. It's not going to freeze in 4h.
Batterys are an issue. They last at best 5 years.
If you insist on maintaining everything, you're probably looking at around 400W for 4h, that's 800Wh, or some 300Ah at 12V.
Maybe 40-80 quid a year for battery replacement.
Thanks. That's good feedback. Unfortunately of the negative kind but that sort of points to their product not being the solution.
Not sure I want to maintain everything. But certainly the 'essentials'. I could live with £40 a year in batteries though.
Any thoughts on the best products to use ?
It's probably more like 200 every 5 years.
Not really. I haven't looked at appropriate products, due to being able to make do with a BEST 600 UPS, fitted with 4 car batteries at a tenner each from the scrapyard.
I'd ask over on alt.solar.photovoltaic, alt.energy.homepower, or alt.energy renewable. Maybe look at any FAQs.
Searched for this on Google and only found links to the batteries used by it.
It's not designed to take car batteries, and is a several year old model that was thrown out as it wasn't working (dead batteries). I added a fan, and a slightly beefier charging circuit.
Sounds like you recommend a brew-it-yourself solution then ? :-)
However.
Many UPSs are designed for short term use. For example, some have heatsinks that are only designed to put up with a few minutes use at nominal load, as the tiny batteries put in it will have discharged by then.
So you've essentially got to make sure that all the components can handle extended loads.
Then you've got the problem of what happens if the microprocessor in the UPS decides that the large batteries are a 'fault', and won't use them, or the charging circuit overheats, or only charges to the original capacity, or ....
For example, one problem with my current setup is that it takes a week to charge after a full discharge.
And then you've got the whole issue of messing around with electronics that can generate enough power to kill, even when unplugged.
DIY can be appropriate - but only if you know enough to safely DIY it.
There are canned solutions, but they tend to be expensive. The solar and other groups I mentioned would probably have some ideas on the easiest way to do it.
(If you manage to kill yourself or burn down your house as a consequence of this posting, I reserve the right to point and laugh).
Will do.
Well I've designed a kW audio amp before and that could fry you without thinking about it.
In article , Mike writes
If you want serious batteries for the purpose then have a search through exidepower, they do the proper high capacity ones, not that cheap but much better than car batteries.
But why hasn't the O/P had a go at the supply company as to why he has such a seeming high number of supply interruption's?....
If your freezer warmed up to such an extent that the temp rose at more than 1C/hr then there is something drastically wrong with it or it's very old and it may well pay to get it replaced. The average freezer will normally still be cold enough without power for 12hrs or more provided you don't open it.
Running a fridge/freezer of a normal computer UPS might be tricky. The induction motors used need 2 to 3 times their running power to start, this may well cause the UPS to trip due to overload. Then of course with big batteries the up time isn't very long. My 700VA UPS can supply 150W (about that of fridge) for 20mins at best.
A small (2 to 4 kVA) generator out back is the easiest solution but be aware of the all the implications of connecting a generator to your normal house wiring. Requirements for fail safe isolation of incoming mains supply, earthing arrangements etc.
So what's the problem? All you need is a 50Hz sine-wave oscillator, some lead-acid batteries, and a charger :)
Actually inverters are nasty to design, because you never know what somebodies going to plug in. For example, a large series universal motor being repeatedly switched from backwards to forwards, ...
If you've got the skills, then you can take a good quality inverter, and a largish 3-stage charger, and connect it to a bunch of batteries.
3 stage battery charger circuit
Not at 10 quid per car battery, and less than that if I replace with an equal mass of old battery. (it's free money for the scrappy, the batteries are just shrink-wrapped after being emptied, and sent off for recycling)
Suppose capacity and dependability aren't in the mindset;)
Pile of batteries, plus battery tester. Two to three times the real need of batteries connected in series/parallel. Occasional observation of balance under load. Works for me.
(You can cause all sorts of problems with imbalanced battery packs, but this is only two batteries in series, so it's not too terrible. And the batteries being relatively slowly discarged is being much nicer to them than in their former life where they are asked to provide 100A surges.
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