Am I correct? Inverter, 12v -220v duration under load.

[Dave100456]

I wish to know how long my 2550va pressure washer will run for if I power it from 12v, using a borrowed 3000watt inverter (90% efficient). Battery capacity is 360AH so say 180 available. I recon about 45 mins. Am I correct?
Thanks

 

[sailorman]

is this a skool test or 4 real /forums/images/graemlins/laugh.gif

 

[Dave100456]

Quote

is this a skool test or 4 real

Did I forget to mention the... If four men were digging as hole at the same time....!!

4 real!

 

[earlybird]

Your nominal 360aH will be at a relatively slow discharge rate, say 20 hrs. Discharge in <1 hr will reduce the capacity available. See Peukert's law. Also, 200+ amps requires hefty cables or significant energy losses will result.
Also, you might well damage the battery with such a prolonged, heavy load.

 

[NorthUp]

It is unlikely that the inverter will be able to supply sufficient power to start an electric motor. Hire an engine driven powerwasher.

 

[mikejames]

The 2.5kW is probably an average - starting loads will be higher. It will probably keep on tripping the inverter . So the answer is about 0.5 seconds each time you hit the pressure washer trigger.

 

[William_H]

Assuming it is not a sine wave inverter but a "modified sine wave" it will probably have trouble running the induction motor of the power washer with any efficiency. So even if it does start it will probably not work well. ie motor get hot inverter get hot or trip. I think the chances of this being a good idea are pretty slim. As said us an engine driven pump. sorry olewill

 

[oldharry]

The biggest problem I can see is that drawing 200amps continuously from the battery will reduce the output voltage pretty rapidly to the point where the invertor is likely to shut down. A heavy discharge tester will draw between 200 and 400 amps (depending on the battery). after a 30 second test, the voltage across the battery terminals will have dropped maybe 25 - 30%. The battery recovers quickly enough if it is good, but I doubt the Invertor will still operate at 9 volts! And if it is it will be drawing an even higher current to compensate for the voltage drop.

You very certainly will not get 12 volts at 200amps for 3/4 hour out of a 400 amp battery.

Check the battery terminal voltage when you are cranking an engine - most starters are actually receiving only around 9 - 10 volts under load. This is why electronics often cut out when the engine is started in single battery installations.

"Dad - you've crashed the computer again!" would be the wail from the forecabin when sailing with my pre-teen son 20 years ago! Had to install a special battery for it in the end /forums/images/graemlins/laugh.gif

 

[cezz06]

Yes it will probably have trouble in running. We've experienced that actually.

 

[Dave100456]

Thanks for all the useful comments and information. This has saved me time in attempting this.

Cheers!