power inverters ?

[glenk]

hello to all,

ok well im thinkin of buying a power inverter to power my tv when we are away watching the bike racing, i normally run a generator (sorry) but we have to when we are in places like that.

my concern is how much juice does it take out of my 110 amp battery, in thinking of maybe a 300 watt, cos all i want is the tv/game console to be on it. We are usually their for three days or so.

has any body had any experience with power inverters , do they work well and would my battery last ? it would only be used maybe 2/3 hours per night .

Looking forward to your comments guys n galls thanks

 

[xtrailman]

glen

The drain from the battery depends on the load.

For a 100 watt load the battery must provide watts/volts= amps

So 100/12=8.3 amps.

Assuming 100% efficiency.

 

[Mikey1]

I bought an invertor to power/charge my laptop whilst away on non EH sites,i found it kept bleeping at me as the voltage dropped on the battery,i ended up buying a dedicated 12v laptop charger.

My invertor is now gathering dust!

 

[ProfJohnL]

Hello Glen,

Rays conversion is fine as he says for 100% efficient inverter, but nothings quite that good, the every best manage about 95% but more typical of the smallish unit only about 80 to 85%. So that will be nearer 10A from the battery to give 100W output. How much power you need is determined by the power consumption of your telly and games system, but assume a pro-rata. Consumption e.g 50w will be about 5A at 12V etc.

The other problem that Mikey experienced is the fact that a long duration or constant drain will cause the battery terminal voltage to fall. Most inverters are really quite clever, If the supply voltage falls, they use more current to try and maintain the output voltage and current. Thishas the effect if increasing the current draw from the battery. Once it falls below a certain threshold, most inverters let you know by emitting an alarm, and if the voltage continues to fall, the unit will actually switch off, to prevent you from completely draining the battery.

With all to other demands on the battery, the second largest is usually lighting, which tends to be on for a long time.

An inverter may not be the best solution for you. There are TV's which will work directly off 12V. these may offer a better viewing experience without interruptions from the low voltage alarm. And as there are less voltage conversions, the overall efficiency should improve.

You might consider a second battery dedicated to the entertainment system. If this is discharged through use, you will still have the use of lights and water pump ect from the original battery.