Advice pls on using a 12v to 240v mains inverter to power TV, SKY, PVR CFL etc

Saver0811

..........

closed

these don't need charging.

Can't you live without tv/sky/internet for 20 minutes, once every 15 years? The battery will probably have gone to heaven before you need it.

https://www.youtube.com/watch?v=aVnGotRzRCc

espresso

Do you need to go to Specsavers!

What you should be measuring, is the current drawn from the 12V battery so that you could calculate how long these items would operate for when powered by an invertor.

neilwoods

It's not the inverters you need to worry about warming up, it is the actual devices.

The more complex the power supply, less likely it will work or survive. Everything you posted apart from mac should be fine, could try mac, may work for a bit but is it worth trying.

Remember though, most inverters are not 100% efficient, more like 85 to 90%.

Also don't forget surge load, if you attempt to switch all those on at same time, something will pop.

What is with the large font size ?

Weird_Nev

Your maths is wrong re the current and life expectancy from a charge.

You draw 130 watts at 0.7 Amps at 240 volts.
From 12 volts, you will need 20X the current = about 14 amps drawn from the battery. Not including inefficiency of the power supply, so call it 20 amps total as you will lose a lot through the inverter.

My experience running car audio equipment of similar current draw is you will get about 1 hour, perhaps 2 at a maximum, from a large car battery before the voltage drops to unusable levels. (remember, low voltage = high current = lots of heat in cables and higher resistance across the system)

espresso

Saver0811 wrote: »

Note: Watts measured is at 240v. Why?
In my view, more relevant is 0.65 amps. Wrong, you need to measure the input current!
For a 40AH battery, that equates to 60 hours !! Very wrong, not a chance!
We shall see, I will do a RT test once my 24 hours measurement cycle is over.

You obviously didn't do enough research into this subject and have a lot to learn e.g. Ohm's law.

Most inverters will draw approx 0.65A input current (12V) with no mains load connected, so think again and do post your actual measured findings.

neilwoods

Weird_Nev wrote: »

Your maths is wrong re the current and life expectancy from a charge.

You draw 130 watts at 0.7 Amps at 240 volts.
From 12 volts, you will need 20X the current = about 14 amps drawn from the battery. Not including inefficiency of the power supply, so call it 20 amps total as you will lose a lot through the inverter.

My experience running car audio equipment of similar current draw is you will get about 1 hour, perhaps 2 at a maximum, from a large car battery before the voltage drops to unusable levels. (remember, low voltage = high current = lots of heat in cables and higher resistance across the system)

Well it won't be that high, but is a lot closer to the mark than what the OP posted.

130 watt at 12v is more like 10 Amp, so overall without imac that is 24 amp draw. with imac, about 30 amp.

As for using battery charger, yes it will work but don't expect the charger to last long, using a modified sine wave inverter.

Plus your using a car battery, shallow cycle. Only designed to allow short burst of high power for a few seconds at most to start the car. So come first power cut, your battery will be knackered after a few hours.

HappyMJ

How often do you get power cuts?

Really...it's overkill. A simple candle as mentioned and a torch and possibly a battery operated radio will do. You don't need TV / Internet.

If you want to cut down the power requirements replace the CFL's with 12V LED lighting...no need for a inverter then.

Avoriaz

I have a lot of elastic bands I no longer need.

I will sell them to you for £20.

You can use them to power your car and save loads of petrol.

neilwoods

Saver0811 wrote: »

I applied a more realistic profile to the Run Time test.

I turned off the TV at 2 hours, and continued with the SKY+HD and other PVRs being powered, ie recordings.

At 8 hours, I terminated the test, with the battery voltage under load being 12.08v

And, the voltage under load should read that anyway to indicate a healthy battery, so mean's nothing.

the lead grid in the car battery is very thin and under high loads will fail fast.

At least you have figured how to use the font sizes in a forum