Any Happy Campers ? Advice on powering TV & SKY+HD Box using a 12v-240v inverter

[#1]

I had all the bits, apart  from a recent 12v Car Battery, Halfords have just had an offer of one for £20. I bought one.
As a backup in the home, I am setting up a 12v Car Battery to 240v Inverter system, hopefully to power a 32" TV, and a SKY+HD Box to view live, record or replay, during a power cut.
Also, my iMacs.
The power cuts are not too often, but usually several hours in length.
Just tested consumption with a plug-in power meter / monitor, all my bits & bobs, ( Router, phones, TP Link, other PVRs )
excluding TV use around 110 watts, 0.55 amps, at 240v. measured
With TV on, this rises to 180 watts, 0.75 amps at 240v. measured
[ I was actually impressed at just how little power is consumed ]
The two inverters ( 150w & 300w ) are both MSW (Modified Sine Wave)

A quick test on a secondary system of smaller TV & CFL showed both working OK, with no degradations.
Before I test using my SKY+HD Box, and iMac, does anyone have any experience of the same ?
TIA

[#2]

Can't you think of anything else to do during a power cut?

[#3]

On a serious note have you not fort of getting a generator?
[Edit]
If yes have a look at this site on Standby Generators

[#4]

180W @ 12V = 15A (assuming a perfect inverter).
Don't watch any long films. 

[#5]

Quote from: jelv

Can't you think of anything else to do during a power cut?

Did you miss the bit about recordings during power cuts ?

Quote from: PlusComUK

As a backup in the home, I am setting up a 12v Car Battery to 240v Inverter system, hopefully to power a 32" TV, and a SKY+HD Box to view live, record or replay, during a power cut.

[#6]

Quote from: Midnight

On a serious note have you not fort of getting a generator? [Edit] If yes have a look at this site on Standby Generators

Yes thanks.
I already have a couple of generators for the heavy stuff, Central Heating, Lighting interior House & Stables, exterior security lights, CCTV....... and so on.

[#7]

A 12volt car battery is not the right kind of battery to use with an inverter.....
Car batteries are designed to absorb a big power consumption when the car is started... and the rest of the time it is "idle"  providing supplementary power for other electrical/electronic circuits,
the alternator provides the Input power, whilst the battery is "discharging" its duties to those electronic and electical items..
what you need for your camping power is a "leisure battery"... where the power is provided ALL the time it is in service... without any "input" power to replace any being used...
This can be the same sort of size as the car battery, but needs to have a "dual charging circuit" to keep it in good condition.... ready for  use....  (usually this "Leisure Battery" is located in a secured place in the boot)....
If you are thinking of using it as a "standby" system at home only, then you need to provide the Leisure battery with a regular top up from a mains powered charging system...

[#8]

I was going to post exactly what Shutter has just posted - he saved me the typing.
You really need to get a leisure battery or you'll end up regretting it at a later date.

[#9]

Yes thanks, I do know about Leisure Batteries.
My mains charger is quite comprehensive, it charges, monitors, detects faults, and goes into trickle charge.
I have used Leisure Batteries in the past ( being an ex-caravanner ), but for £20 ...!!!
Cheap enough to recycle when the time comes.
My previous Car Battery providing a similar service lasted 7 years.

[#10]

I used to use an inverter in my caravan when we started caravanning. I used to run my laptop from the inverter to watch stuff I had on the hdd. I also have run everything from a battery when I got a freesat receiver that was powered from 12V, the 19" lcd I TV I have for the 'van is run from 12V, so I added a couple of 12V o/p's to the strip above the TV and they get powered from there.
For long periods (like 2 weeks away) I would remove the battery and charge it while we drove about.

[#11]

HB, thank you for your excellent input, just what I was looking for.

[#12]

Quote from: PlusComUK

Just tested consumption with a plug-in power meter / monitor, all my bits & bobs, ( Router, phones, TP Link, other PVRs ) excluding TV use around 110 watts, 0.55 amps, at 240v. measured With TV on, this rises to 180 watts, 0.75 amps at 240v. measured [ I was actually impressed at just how little power is consumed ]

By removing an item I would not need during a power cut, I can reduce my base consumption down to 30 watts, with TV, 100 watts, a vast improvement.

But more likely, I would not have any TV on, just the PVRs to record items. (30 watts)
The PlusNet Wifi router has its own independent 12v battery power supply, which I made for it.
To use in conjunction with either my Smartphone, with a live TV app, or my portable NOW TV setup, discussed elsewhere.

[#13]

Being on a remote farm my parents get power cuts all the time.
Dad built a little box outside the lounge window and run a cable to the tv.
In the box he has 2 big tractor batteries, a fuse box, converter etc, then an extension lead to the back of the tv.
To keep the batteries charged he has 1 of these permanently hooked up.
http://www.ebay.co.uk/itm/BRAND-NEW-1-5W-12V-Solar-Trickle-Car-Battery-Charger-PS-A015-/190741682264...
Obviously after the powercut, he charges the batteries over night.

[#14]

But not with the Solar Trickle Car Battery Charger !!  
Nice story.

[#15]

haha well no of course..