Inverters

[Jimb]

Need advice re an inverter for a van, I intend to put a fridge in the van and to run some other 230 volt items using a second leisure battery charged rom the vehicle alternator, if I get a 1000 watt 230 volt inverter will it use the full current from the battery all the time or will it react to demand, for example if the demand is 200 watts will it only use enough battery current to supply 200 watts ???


Thanks in advance

 

[GSmonkey]

It will react on demand. There will be a base load the inverter takes, but it should only be milliamps to run the electronics and fans. They are high efficiency devices, but you may still get a few percent loss on top of this. You do realise that 1000 watt is a big load for a leisure battery i.e. over 80Amps. It certainly won't run a 1000 watt load very long.

Also if you're using a fridge with compressor, the motor can require quite a starting current, sometime six times full load current - it could cause problems with the inverter depending upon the rating of the motor.

 

[wessie]

The unit will only draw a small current from the battery unless there is a load on the output. When there is a load it works as you describe i.e. draw only enough input current to satisfy demand plus any losses through inefficiency (heat mainly).

All based on Newtonian physics: all systems must be in balance.

As an example, this unit http://www.dcacpowerinverters.com/itemdesc.asp?CartId={2957D0F3-6FF4EVEREST-4585-9FD8-CB5B26114063}&ic=PW900-12 draws just 0.9A of current at 12V if left connected to a battery when there is no load on the output. Ignore the rest of the spec. as it's American, just pulled it from google at random.

 

[(RIP) Proff]

3way

Hi Clive.
I use a 1000w inverter on a 110 AMP Leisure Batery for the A/C on my van.
seems to last about 4 hours before I need to top it up by running engine or starting Genny.
'bout the fridge, Wouldn't a 3 way be better , 12v when engine is running / 240 on hook up or at home, and Gas when freecamping?
there about same price as a descent house fridge and theres loads in Caravan Breakers. @around 50 to 100 quid

 

[Jimb]

Gents

Thanks very much for the info, youv'e answered my questions, yes I'm aware that 1k watts is high but as GS monkey points out the start load is much higher than the running load, I considered a 3 way fridge but have ruled it out because the gas needs to be vented to the out side which would require cutting an inlet and outlet panel in the vehicle body, there are dual 12 / 240 volt models that will do the job nicely for my purpose.

Also like Proff I intend to have one of the super quiet generators as well.

Thanks fella's