Inverter Question

[eurovanman]

I have a simple question. If I am running a 100w device off of a 1,000w pure sine inverter will it use the same amount of battery power compared to running a 100w device off of a 400w pure sine inverter? Is there any downside to going with a larger inverter?

JP

[gerrym51]

Originally Posted by eurovanman

I have a simple question. If I am running a 100w device off of a 1,000w pure sine inverter will it use the same amount of battery power compared to running a 100w device off of a 400w pure sine inverter? Is there any downside to going with a larger inverter?

JP

yes

[booster]

I think it depends a lot on the inverter and it's efficiency. I also think efficiency changes with % of rated power load.

If they are both high quality efficient ones, I think you would be pretty close to the same at that small a load.

[Davydd]

For the 100W device it doesn't matter as it will work with both. I assume the larger inverter will use more power off your batteries when running by itself regardless as to what is connected to it, but probably nothing to worry about. The 1000w inverter will handle more or larger devices. That's a plus.

[mkguitar]

My electrical brain suggests to me that the load on your system will be at least partly dependent on the load placed on the inverter.

What I would do is to measure the current load of each type inverter ( with an ammeter) both at a steady state ( no load) and under load.( an easy way to get an accurate "amount of load" is with light bulbs...100w = 100w which at 120 volts is about .85 amps @ 12 volts = about 8.5 amps

Failing an ammeter, put the question to the manufacturer of the inverter(s).


Mike

[FredA]

If you find the data sheet for the particular inverters in question on the manufactures web site, you can usually find a specification for the power it draws from the batter at no load.

Some manufactures spec the no load power in watts. Others indicate the DC drain with no AC loads. It is going to be the same thing.

Watts are the product of volts and amps. So if they specify watts you can divide by 12 to get amps.

For example, the Outback Power 2800 watt inverter has a specified no load power of 20 watts. So if is going to draw 1.6 amps with no AC load.

I looked up two Xantrex inverters one was 1000 watts and the other 450 watts. The 1000 watt was specified as having a 6 watt no load power. Therefore .5 amps. The 450 watt was specified as having a battery drain with no load of .25 amps. This is an example of one manufacture specifying the same thing in two different ways.

That no load power is what the inverter needs to run itself. So it will be consumed all the time.

Many inverters also have a search capability. They will shut down to a lower power level if their is not a load. Then periodically they will switch on and see of a load has been turned on. That way the average idle power is lower.

[eurovanman]

Lots of great answers. Thanks, I reckon its nothing to worry about, I'm sticking with my 1000w inverter.