Microwave question

wannaSMB · 12-19-2008, 04:09 PM

Anyone have any experience with something like this?

http://www.sportsimportsltd.com/mi800wapoinv.html

We want to add a microwave but do not have a house inverter (and do not want to spend $1400 on one). Any thoughts or input are welcome.

jage · 12-19-2008, 05:58 PM

That's a power invertor and a microwave- note the 800 watt invertor and the 550 watt small microwave, there doesn't seem to be anything special except that they already figured out how much invertor you need for the microwave.

You might as well go buy a small microwave locally (check the watts) and then find a deal on a nice invertor that will support it.

Either way you should be fine. Be sure to run the van or have a house battery separated/isolated.

wannaSMB · 12-19-2008, 06:06 PM

Yup, the only issue is the degree to which they have confirmed in advance that the particular microwave will work with the particular inverter. None of these plug-in style inverters are true sine wave, so don't know if a std. AC microwave that I buy locally will work with a cheapo inverter.

But I know very little about this stuff: am I worrying about nothing?

jage · 12-19-2008, 07:18 PM

Yeah sorry, true sine is so there is not electrical interference for sensitive equipment like computers, although most computers would probably be fine. The microwave doesn't care any more than a drill would if the power is pure or not.

So watts is the measure of power, the microwave is listed at 550W but to be safe account for 150% because when you start most anything, even the drill, the power cost is more than what it is rated.

So the microwave fires up at around 800W but then runs at 550W, so that is why they choose an 800W invertor.

My toaster oven is 1300W (although technically I don't think there is a startup cost since there is no motor) to be safe I have a 2000W invertor.

So- when you find microwave check the watts and multiply by 1.5 and that will tell you about what size invertor you need. The ones SMB installs also act as a charging circuit, so even if you need a 2000W generator you can get an invertor similar to the one pictured at substantially less.

Check around too the prices can vary widely.

wannaSMB · 12-19-2008, 11:14 PM

Thanks Jage. Exactly what I needed to know. Sounds like the way to go. Plus it'll give me an extra AC outlet with plenty of wattage when the oven is not in use.

Psomaki · 12-19-2008, 11:53 PM

This has been covered in other threads, but might bear repeating here. Yep, you'll have an extra AC outlet with plenty of wattage BUT all that wattage will come out of whichever battery you hook the inverter up to. I.e., either your house battery or your chassis battery. That was the basis for the good advice above that you run your engine when running the microwave - so that the motor would be powering the alternator which in turn would be providing DC to the battery. So let's say you don't run the engine, just hook up the inverter to the battery and run the microwave. Once the 550-watt microwave gets started, it'll be drawing 550 watts. The inverter causes some power loss; for the sake of discussion, let's say 50 watts. So you're pulling 600 watts from your battery. One watt of power is one amp of current flowing with one volt of potential. Or simply put, W=VA. So your fully charged battery is maybe 12.7 volts. To keep it simple, let's say 12 volts. Your microwave/inverter setup demands 600 watts. Divide 12 into 600 and you get 50, which is how many amps your battery has to put out to run the inverter and microwave. Batteries are rated in ampere/hours. How many is your battery rated at? Some two-battery house battery sets can be rated up to 200 ampere/hours (or even higher). If you've hooked this whole rig up to such a house battery set, and if you follow the rule of not discharging your battery below 50% of full charge, you can run your microwave for two hours before your battery reaches the dangerously discharged level. Hook that rig up to a 60 ampere/hour chassis battery and you can run the microwave for a little over one half hour. No big deal if you just want to pop some popcorn or heat up some nachos, but pretty important if you intend to prepare a meal this way, especially if after you prepare the meal, you want some juice left over to run your fridge or keep your lights on or etc. etc.

**daveb** · 12-20-2008, 08:47 AM

Also be aware what low temps do to a battery. The total amp hours a battery can hold is much less at freezing temps. What worked at 60 degrees might drop a battery to damaging voltages at 30 degrees much quicker. I also try to use the microwave on medium power for a little longer rather than short periods at high. This also will extend how long the battery will hold a charge especially if you're running the vehicle. Just experment a bit and monitor the voltage...always let the battery float back up before checking the voltage.
Dave.

Stumpalump · 02-18-2009, 03:38 PM

I just ordered a Wavebox microwave. It's 110v or 12v. They seem to be staying sold out but Cabellas can get them in a few weeks. It's ABS plastic with nothing to break.
http://www.thewavebox.com/
Youtube vid

http://www.youtube.com/watch?v=XnprSa9W ... re=related

jage · 02-18-2009, 04:53 PM

How do you tell when the cheese is melted?!

Stumpalump · 02-18-2009, 07:40 PM

I guess you wait untill it's so melted you can smell it burning! Whats camping without eating a little burnt food anyway??? No window is really stupid but it saves me from buying a bigger inverter than I allready have because it runs right off 12V. I can also just grab it and relocate to a more convienent place in my rig if I want to use it. Just seems like a tuffer solution to my microwave needs. I'll post back when I get it and let you know if it's a chezzy gadjet or not but wanted to post up before hand because of the limited availability this close to camping season. Cheers.