12 volt microwave

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pcatterall

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I need a small microwave to be used mainly with shore power but would like the possibility of using from 12 volts.
I have seen one ( called Wavebox) which runs from either (660watts)
My other option was a small domestic one ( max) 800 watts and a 1500 watt (?) inverter.
Any advice/experience Please.
 
The matter has been covered before but threads are difficult to find.

IMHO unless you have a large boat with serious battery capacity and/or very big alternators the 12v option is not desperately practical.

660Watts at 12 Volts would incurr a current draw of 50 amps plus so massive load on battery or alternator and large cables needed to power it.

Others may disagree.
 
pcatterall said:
I need a small microwave to be used mainly with shore power but would like the possibility of using from 12 volts.
I have seen one ( called Wavebox) which runs from either (660watts)
My other option was a small domestic one ( max) 800 watts and a 1500 watt (?) inverter.
Any advice/experience Please.
Click to expand...

Not knowing about the existence (sp?) of 12v microwaves, I went to Tesco's and bought a 700w 240v model for £29.95 and then went to Towsure and bought a 1000w continuous, 2000w peak modified sine wave inverter for £99.50. The m/w has a max draw of 1200w on full power and seems to run very happily on mod. sine wave. The inverter also seems to run anything else that I plug into it, including a fan heater (admittedly on half power - 'bout 1000w I'd guess) and is reet handy for boiling an 800w kettle mid Solent for a cuppa. It has worked flawlessly since purchase 18+ months ago and I will buy another when I change boats. IF you are carefull with your usage ie don't boil a full kettle for a cuppa it doesn't seem to trash the batteries either. I'd reccomend it based on my experience. Oh and yes, it draws 0.5 amps on standby...........but I don't leave it on standby, just turn it on when I need it. I also try not to have more than one appliance running at a time.
PS When wiring it in, I placed it 3 feet from the batteries and used f**k off great big cables, 38mm square if I recall correctly.:D Seems to work OK!

Caution: this user is NOT an expert..........on anything except perhaps anaesthesia.:D
 
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Thank you 'Havn't a clue'!
Godd to read " I did this and these are the results" rather than just theorising!!
Those 12 volts I reffered to were too small when I checked the internal size compared to cooking bowls and plates.
I will go your way and get a low power smallish mains version and an inverter.
I then need to consider where to mount and how to wire in the inverter.
Clearly its the lead from battery to inverter that carries the big current so that needs to be short and thick.
Can I wire an inverter into my mains circuit? more searching on that one required!!
 
Can I wire an inverter into my mains circuit? more searching on that one required!![/QUOTE]


Hi-
You need to be able to avoid having the inverter and mains hookup connected together. (Mental image of inverter trying to power Southampton :rolleyes:)

Use an appropriately rated twin gang two throw switch (ideally with an off as well) Like a 1-2-both switch without the 'both'

Try generator suppliers if local elec wholesalers can't help.

Nick
 
Easier way to connect is to have an adaptor lead - 13a plug into the inverter and a 16A plug into your normal mains inlet. You can't make a mistake then.
I concur with the oppinions on this - I have used a microwave / mains a/c etc on a camper and boat using a 2kw modified sine wave inverter with great success.
The thicker and shorter the cables the better. Good inverters usually have double cables to connect to 2 batteries.
 
davidpbo said:
The matter has been covered before but threads are difficult to find.

IMHO unless you have a large boat with serious battery capacity and/or very big alternators the 12v option is not desperately practical.

660Watts at 12 Volts would incurr a current draw of 50 amps plus so massive load on battery or alternator and large cables needed to power it.

Others may disagree.
Click to expand...
Yea, I would think you are going to be replacing batteries rather alot at that draw.Best manage life without the microwave and eat something else if no shorepower!
 
No doubt 12v microwaves have their place, but unless you can install them right next to the batteries, the cost of the heavy-duty cabling will be considerable. In any case, they are just a conventional microwave with a built-in inverter.
I use a rig that's almost identical to that described by Haven't-a-Clue, no problems so far. Short, heavy duty leads were supplied with the inverter. Mains lead can be pretty much as long as you want. As well as being able to power the microwave, the inverter is also handy for running power drill, angle grinder etc. The only thing I've so far found that it won't handle is the recharger for my portable power drill.
As far as current draw is concerned, this is around 80A when running the microwave, but as it's only run for a few minutes at a time, it won't harm the batteries.
 
greenalien said:
As far as current draw is concerned, this is around 80A when running the microwave, but as it's only run for a few minutes at a time, it won't harm the batteries.
Click to expand...
I am no expert, but I am guessing you dont have 150a batteries...
Can you really draw 80a from an medium battery say 110am for 5-10 mins without any issue with battery life? Not a normal leisure one surely?
 
Bassplayer said:
Easier way to connect is to have an adaptor lead - 13a plug into the inverter and a 16A plug into your normal mains inlet. You can't make a mistake then.
I concur with the oppinions on this - I have used a microwave / mains a/c etc on a camper and boat using a 2kw modified sine wave inverter with great success.
The thicker and shorter the cables the better. Good inverters usually have double cables to connect to 2 batteries.
Click to expand...

What stops you plugging both in at the same time? Or do you mean a 16A socket? That would work, I have done the same in a camper using computer 'kettle' plug/sockets. Bit of a lash up though with a nest of lose wires. I was the only person who understood it!

edit- just found a switch- too pricey for me!

http://www.genpoweruk.co.uk/100_amp_Moeller_Changeover_Switch.html

N
 
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pcatterall said:
I need a small microwave to be used mainly with shore power but would like the possibility of using from 12 volts.
I have seen one ( called Wavebox) which runs from either (660watts)
My other option was a small domestic one ( max) 800 watts and a 1500 watt (?) inverter.
Any advice/experience Please.
Click to expand...

I don't know if your boat is motor or sail but I generally agree with the others.

Buy a 240v domestic microwave - very cheap and plenty of choice. Definately not the case with 12v jobs.

If your boat is motor then using an invertor when your engine is running shouldn't be much of a problem as you will be recharging your batteries. However, if your boat is sail, you'd be better off avoiding a large invertor.

Think of sensible power (and financial) management, how often will it be absolutely essential for you to use your microwave when you are disconnected from shore power? Ever heard of pork pies and scotch eggs?
 
gjgm said:
I am no expert, but I am guessing you dont have 150a batteries...
Can you really draw 80a from an medium battery say 110am for 5-10 mins without any issue with battery life? Not a normal leisure one surely?
Click to expand...

I don't think anyone fitting a big inverter would have just a single battery. Many inverter manufacturers recommend a minimum battery bank size. For example, Xantrex recommend at least 200Ah for loads up to 1000W, and minimum 400Ah for bigger loads.
 
I am guessing you dont have 150a batteries...
Can you really draw 80a from an medium battery say 110am for 5-10 mins without any issue with battery life? Not a normal leisure one surely?
Click to expand...

My inverter is connected directly to my 135Ah starter battery (I intend to add a 150A fuse in the circuit, currently on order); this is backed up by 1 x 185Ah gel battery and 2 x 135Ah deep cycle batteries when I put the battery switch to 'All', which I do if running the inverter with the engine off.

Running the microwave for 5 minutes drops the battery voltage overall by 0.2 volts; if I run the engine, there's no voltage drop, but the engine does have a noticable, temporary drop in revs when the microwave is switched on! The engine, a Bukh DV20, has a 110A Prestolite alternator - the original 30A device wasn't up to the job.
 
Thanks Guys,
My liesure bats total 165 AH I don't plan to use the microwave on battery just thought it might be nice to have the facillity on the odd occaision, ie if I am motoring.
I had considered the actuall amount of draw but had not considered any implications on damage to the battery say from drawing at 50 amps for 10 mins??
 
NickRobinson said:
What stops you plugging both in at the same time? Or do you mean a 16A socket? That would work, I have done the same in a camper using computer 'kettle' plug/sockets. Bit of a lash up though with a nest of lose wires. I was the only person who understood it!

edit- just found a switch- too pricey for me!

http://www.genpoweruk.co.uk/100_amp_Moeller_Changeover_Switch.html

N
Click to expand...

My Catalina 36 had a fancy inverter set up. If the kettle was boiling on shore power and we diconnected from it, it would carry on boiling on the inverter. Mind you the battery bank was the size of a football pitch! :)
 
Bassplayer said:
Easier way to connect is to have an adaptor lead - 13a plug into the inverter and a 16A plug into your normal mains inlet. You can't make a mistake then.
I concur with the oppinions on this - I have used a microwave / mains a/c etc on a camper and boat using a 2kw modified sine wave inverter with great success.
The thicker and shorter the cables the better. Good inverters usually have double cables to connect to 2 batteries.
Click to expand...

Yup, that's how I do it, a lead from the output socket of the inverter to the shorepower inlet. As there is only one shorepower inlet, either the shorepower lead or the inverter lead can be plugged in, but not both, so no problem. Re the inverter wiring, as I posted earlier, I used BIG fat cable from the 'both' terminal of the 1-2-both switch, so the inverter always draws from both (110Ah) batteries. For the (800w) kettle, the engine doesn't have to be running, however, if I'm running the m/wave I always run the engine. Saves the embarrasment of having to get the genny out to recharge the batteries!!
 
pvb said:
Surely that depends on whether you've first set the switch to "Both"?
Click to expand...

ER, well, yes, didn't I say that......looking back, no I didn't....ho, hum, thorry:o

Ah, I see the confusion. When I said I run the m/wave, I said I ran the engine...and I always run the switch in the 'both' position when the donk's going, that's what you're supposed to do, yes/no?

I'm not saying this very well, am I.:D
 
pcatterall said:
Yes the extra lead idea sounds good and simple to me!!
If the inverter is permanently connected to the batteries is there any draw? should there be a big switch there as wellas an 100amp fuse?
Click to expand...

My master switch has a 100A breaker incorporated.........and the inverter has an on/off switch, so when not in use, it's switched off, so I presume no draw.....I stand to be corrected if this isn't the case.
 
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