Inverter Question

[SteveW]

Let's suppose I want to run a 240v device that uses 100w.

If I use an inverter that can produce 1000 watts max, will that use any more 12v battery capacity to operate my 100w device than if I use an inverter that can produce only 150 watts max?

[oldtrack123]

Let's suppose I want to run a 240v device that uses 100w.

If I use an inverter that can produce 1000 watts max, will that use any more 12v battery capacity to operate my 100w device than if I use an inverter that can produce only 150 watts max?

It will be slightly less efficient than one operating near full load ,as they all have a standby current as a % of the output

Much would depend on the SPECS of the actual inverters

PeterQ

[BruceS]

I did a series of tests some time ago Steve.
I 'saw' 61 watts on my meter running off a power point & 63w running through a 600w inverter when using a desklamp with a 60w globe in it. (same lamp)
The better quality ones (or should I say recent ones?) have a very small overhead. (in my opinion)

I found a very similar result using a Toshiba laptop.

[T1 Terry]

Let's suppose I want to run a 240v device that uses 100w.

If I use an inverter that can produce 1000 watts max, will that use any more 12v battery capacity to operate my 100w device than if I use an inverter that can produce only 150 watts max?

The inverter will have a standby current and and no load current, cheap ones, a no load current only, really good ones, a no load, standby and search mode. The Victron Multiplus 12/1200/50 inverter/charger has a 8w no load, 5w standby and 2w search mode, that's about as good as it gets. So, at 1000w the load would be approx 1008w, probably a bit more because the fan would kick in after a while, at 100w the load would be 108w, fan probably wouldn't kick in for quite a while.
The cheaper units are often around 0.8 amps to 1.2 amps, that's about 10w to 15w, the down and dirty rule of thumb is add 10%, you don't get any nasty surprises then.

[SteveW]

So, leaving aside small discrepancies, using an inverter that is much larger than needed for most circumstances will not result in wast of power. Correct?

[T1 Terry]

Some waste, but very little in the scheme of things. If you were to run a 10w load with a 1000w inverter for 24hrs you would waste 24Ah, about the same as just leaving it turned on doing nothing.

[TigerMK1]

I have also found that the standby usage of inverters varies quite a bit. My previous 2000W unit used about 90ma on standby. My latest 2000W unit only uses 40ma on standby. It also has a peak load of 3000W to start those big start motors. It also has no problems with running our F&P domestic fridge 24/7. The previous chinese cheapie gave me nothing but trouble.