What to do in a power cut

rogerblack

zeupater wrote: »

Hi

If it doesn't trip out when the compressor fires up it would likely run from full charge to completely flat in around 10minutes with a single refrigeration unit (Spec: Full load 500W = ~5min with new batteries ?),

Err - no.
Most domestic fridges/freezers including the 300l hotpoint one I was referring to above - use about 100W.
In that units case, around 90W, dropping to about 80 as the refrigeration cycle goes on.

It so happens also that I got a bit annoyed at the local distributor, and put some of the compensation for downtime into a couple of large batteries - the UPS would run the fridge/freezer for about 3 days.
(2kWh).

zeupater

rogerblack wrote: »

Err - no.
Most domestic fridges/freezers including the 300l hotpoint one I was referring to above - use about 100W.
In that units case, around 90W, dropping to about 80 as the refrigeration cycle goes on.

It so happens also that I got a bit annoyed at the local distributor, and put some of the compensation for downtime into a couple of large batteries - the UPS would run the fridge/freezer for about 3 days.
(2kWh).

Hi Roger

That's why I included the text ".... unless you have a seriously large external battery array wired up ....", which you have confirmed is the case.

Although some freezers could consume ~100W it would be irresponsible to assume that 'all', or even anywhere approaching 'most' would (especially larger ones). Most of the recent efficiency improvements in refrigeration units are linked to insulation thickness, material technology and design reductions in thermal bridging than anything else. If you consider that a typical modern unit would be energy rated at ~1kW/day (standard test at 25c) and that the cooling cycle is around 12minutes/hour (20%) of run-time then power draw would average ~200W(1000/24/0.2) ... of course, the power will have an initial inertia spike as the compressor kicks in which could be in excess of 500W for a second or so, will draw considerably more power than average when pulldown starts and then stabilise for the rest of the cooling cycle ...

Anyway, just in-case someone is seriously considering doing this, back to the UPS ... having many years experience with critical application UPS equipment rated at anything from ~200VA up to ~100kVA I wouldn't consider even thinking about (and certainly wouldn't recommend) running a standard freezer via a 750VA unit (likely 500W~600W rated) which is appropriate for something like a small server or similar application ... especially so if it was to be used for an extended period ... there doesn't seem to be a large enough safety margin considering that overload protection on a UPS can be very strictly applied. Additionally, an APC 750XL unit maxed out with 4 extension battery packs would be rated for ~1000 minutes at 200W, that's around 3.5 days autonomy for a ~200W freezer (25C ambient) at a cost of around £2000 every 5-8 years or so (batteries need replacing) on top of the additional electricity used ... a generator and a can of fuel would be much cheaper ...

HTH
Z

monicaG84

In case of a power cut I always make sure I have at least 3 boyfriends at any one time. Then, I'm assured of a warm bed, and of supplies for the forseeable future

[Deleted User]

One good thing about a UPS is you see all this nonsence, attached...

https://dl.dropboxusercontent.com/u/7521506/apc.PNG

Fruit_and_Nut_Case

jeepjunkie wrote: »

One good thing about a UPS is you see all this nonsence, attached...

https://dl.dropboxusercontent.com/u/7521506/apc.PNG

This link gives an Error.

[Deleted User]

Sorted, hopefully...:o