Pure sine wave for Microwave

[Otter Spotter]

I have a Bosch microwave/grill in my van which we only use on EHU as it’s 900w model, I have a 3000w invertor (not pure Sine Wave).
Question- Do I need to replace existing invertor to use Microwave off grid ? Or will the existing invertor be up to the job and not damage the microwave?

Electricity in its many creations is not my thing, I still cannot get my head around Amps, Watts, battery life, etc.

 

[bigtwin]

Be aware that the 900W that you quote is the heating power and not the power consumption figure that’ll more likely be around 1.3kW.

Ian

 

[Otter Spotter]

Bumped

 

[funflair]

I would yes you need PSW, when we bought our last van it had a Quasi sine wave and when I fitted a microwave it went through the motions and did everything but heat anything up, changed to 3kw PSW and "bingo" it worked a treat.

 

[Millcourt]

I can not think of any reason why the equipment ratings you describe would do any harm to the inverter, but I would not risk the electronics in the microwave oven with a non-pure sine wave model.

Also, you need to be sure you have adequate battery capacity to run a microwave oven for the time required....... when running it is likely to be drawing a current of at least 80 amps and probably nearer 100 amps, depending on the efficiency of your inverter etc. So, as a guide, if you run your microwave for 15 mins you will use something like 25 Ah (Ampere-hours) of your battery capacity.

You don’t say how much battery capacity you have. Unless you have increased the size of your battery bank, a typical Panel Van Conversion is equipped with a single leisure battery of (usually) no more than 100 Ah, of which you cannot really expect to use more than 50 Ah (unless it is, for example, a Lithium Battery) without seriously reducing the life-span of the battery. Bear in mind also that you will have other power demands drawing current from your battery when off-grid.

Hope this may be helpful.

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[Otter Spotter]

Battery is 190ah AGM at present, not so much concerned about the invertor being damaged it is the microwave I was concerned would be ok to operate with non PSW.

 

[Richard n Ann]

Battery is 190ah AGM at present, not so much concerned about the invertor being damaged it is the microwave I was concerned would be ok to operate with non PSW.

You really need 3 batteries to supply 100 amps, so they supply a more battery friendly 33 amps each. Or there's the lithium option

 

[Otter Spotter]

You really need 3 batteries to supply 100 amps, so they supply a more battery friendly 33 amps each. Or there's the lithium option

Where do I sit then

 

[Richard n Ann]

Where do I sit then

Use a gas oven

 

[Raul]

Battery is 190ah AGM at present, not so much concerned about the invertor being damaged it is the microwave I was concerned would be ok to operate with non PSW.

For a quick work out, divide the total battery capacity by 5, and will give your max draw amps. In your case 190ah : 5= 38a draw. Take that via inverter 38a x 12v = 456w. Take 10% for efficiency of inverter, 45,6w, that leaves you with a max 410,4w max at 230v. You really need 3 times as much to run that 900w microwave. Also it’s a very inefficient on power factor. The inverter will supply 1000w, ( apparent power), but microwave it will only absorb 800w. The 200w is a reactive power that returns to inverter and cycle starts again. This would be a 0,8 power factor. Anything we plug in our sockets could be from as low as 0,6 to 1 power factor. A boiler heating element will be 1 PF as it’s a resistive load and will swallow anything you trow at it, even dc, it wouldn’t care.

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[Otter Spotter]

Use a gas oven

Nooooh! No gas in van we use a Wallas Diesel hob and heater, gas is dangerous

 

[Otter Spotter]

For a quick work out, divide the total battery capacity by 5, and will give your max draw amps. In your case 190ah : 5= 38a draw. Take that via inverter 38a x 12v = 456w. Take 10% for efficiency of inverter, 45,6w, that leaves you with a max 410,4w max at 230v. You really need 3 times as much to run that 900w microwave. Also it’s a very inefficient on power factor. The inverter will supply 1000w, ( apparent power), but microwave it will only absorb 800w. The 200w is a reactive power that returns to inverter and cycle starts again. This would be a 0,8 power factor. Anything we plug in our sockets could be from as low as 0,6 to 1 power factor. A boiler heating element will be 1 PF as it’s a resistive load and will swallow anything you trow at it, even dc, it wouldn’t care.

Cheers this I think I can understand, simply, don’t use Microwave off grid