convert dc to ac ?

[bubbakat]

My wifes son-in-law drives a truck and he wants to put a microwave in it. They have a small one left over from wedding gifts so here is what I need. The data plate says 120 vac at 60 hz<br />What size of inverter does he need or is that converter. Guys keep it basic because I am not going to buy it for him. and you know how younguns are with money

 

[bomar76]

Re: convert dc to ac ?

You left out the one piece of info that would tell you how big...the watts or amperage of the oven.<br />Regardless, microwaves draw a lot of current, and it takes a darn big inverter to run one and it will need to be hard wired to the battery.<br />Truck stops (TA,Flying J, etc) sell 12v microwaves, they are not too expensive.<br />Big inverters are not cheap.<br />Post the amperage or wattage.....

 

[bubbakat]

Re: convert dc to ac ?

That is what is holding me up bomar it is not stated on the unit.<br />I am with you on this I think he would be better off buying one already converted. The surge protection alone would make those things costly

 

[bomar76]

Re: convert dc to ac ?

By law, somewhere it has to state either the wattage or the amperage.<br />Without that there is NO WAY to guess the draw.

 

[bomar76]

Re: convert dc to ac ?

You could put somewater in it , plug it in and use a clamp on meter to measure amperage....have a Fluke laying around?

 

[bubbakat]

Re: convert dc to ac ?

750 watts -----65 amps

 

[Xcusme]

Re: convert dc to ac ?

YEEEOOOOW!!! I think you're missing a decimal point there....perhaps 6.5 Amps??

 

[JB]

Re: convert dc to ac ?

Any inverter that can run a 750W Nuker is going to draw about 100amps from the battery (far less than 100% efficient).<br /><br />Nuke something for 3 minutes and you have fried any cables less than 4-0 and maybe blown your battery to bits.<br /><br />Tell him to get a 12V nuker. Probably be about 200watts.

 

[POINTER94]

Re: convert dc to ac ?

Volts x Amps = Watts<br /><br />therefor<br /><br />750 watts divided by 115v = 6.5amps Yep 6.5

 

[POINTER94]

Re: convert dc to ac ?

sorry

 

[ZmOz]

Re: convert dc to ac ?

Originally posted by JB:<br />Any inverter that can run a 750W Nuker is going to draw about 100amps from the battery (far less than 100% efficient).<br /><br />Nuke something for 3 minutes and you have fried any cables less than 4-0 and maybe blown your battery to bits.<br /><br />Tell him to get a 12V nuker. Probably be about 200watts.

It will use more like 70 amps. Todays inverters are extremely efficient, around 90%. Unless there's 100 feet of cable something like 1 gauge would probably be plenty. Starters draw around 500 amps and most factory starter cabling is 8 guage. As long as the truck is idling there would be no problem running a 750 watt inverter for quite a while. I have never actually seen a true "12 volt" microwave, and I've looked pretty hard. Any "12 volt" microwave is just a low wattage microwave that comes with an appropriately sized inverter in the box. 200 watts will not run any microwave. The smallest microwave I've ever seen is rated at 500 watts, and that's the microwave output, not electric input. A 500 watt microwave will use about 700 watts...

 

[eurolarva]

Re: convert dc to ac ?

Hey pointer Bubbas math is correct . You need to consider the 12 volts not the 110. So you are 750 watts / 12 volts = 62.5 amps

 

[John Carpenter]

Re: convert dc to ac ?

Not to be argumentative, but Pointer94's math is correct. Both microwaves and inverters are commonly rated by wattage. I am looking at West Marine's catalog article "How to Select Inverters"....page 619 in the 2004 Master catalog. Looks like if you want to run a 750 watt load, then you should buy an inverter rated for 750-1,000 watts. They have a hard wired model from Xantrex rated at 800 watts continous for $249.00. It will run your microwave. Could be that you can buy it for less somewhere else...like here?

 

[ZmOz]

Re: convert dc to ac ?

$249 is a complete rip off for an 800 watt inverter. I've bought 3 coleman's for $49. Even though they are rated at 800 watts I've used them with about 900 watts continuously without a problem. Also remember, if you've got an 800 watt inverter, the most microwave you can run is probably 5-600 watts. The watt rating on microwaves is the output in microwave energy, not input of electricity.

 

[SS MAYFLOAT]

Re: convert dc to ac ?

Hey there Bubbakat, I have a microwave in my galley. Its 110v 550 watts. I use a 2000 watt generator to run it, and it really draws on it big time. Can't run anything else while it is in use. An inverter would have to be real big with a big battery bank. Big bucks...<br /><br />His best bet is one made for 12vdc, they work, but it takes awhile to really heat anything.

 

[POINTER94]

Re: convert dc to ac ?

Hey pointer Bubbas math is correct . You need to consider the 12 volts not the 110. So you are 750 watts / 12 volts = 62.5 amps <br />

Are you sure???? The refrigerator is AC and therefore rated in 120v (that was the question at that point in the discussion) I was just referring to the draw of the AC refrigerator. The inverter would draw 65 amps @ 12V assuming near perfect efficiency to run refer.

 

[John Carpenter]

Re: convert dc to ac ?

The comment by ZmOz regarding how microwaves are rated got me to thinking. He's right...but we are all looking at this wrong. The rating of a microwave in watts has nothing to do with it. The draw in amps that it takes to run it is what you need to know.<br /><br />I just went in the kitchen and checked inside the door on mine. It is a Panasonic, rated at 1000 watts. Current draw at 110V is 12.8 amps. Therefore 12.8 X 110= 1408 watts. It would take a pretty good sized inverter with a large battery bank to run that sucker. Guess that's why it pops that 15 amp breaker from time to time.<br /><br />My father was an electrical engineer and so is one of my best friends. They snicker when I pretend to know anything about electricity except how to get shocked. So take the above with a grain of salt..but I think it is correct.

 

[POINTER94]

Re: convert dc to ac ?

Relentless,<br /><br />Checked mine and you are right they are not a 1 to 1 type of ratio. 9.6a X 120v = 1152w and mine is rated at only 750 watts. As mine was made in malaysia, it must be some kind of conspiracy to mess with our minds...

 

[SS MAYFLOAT]

Re: convert dc to ac ?

Hey guys remember this. Your stepping up 12 to 110, then in the microwave your stepping it up again. Major loss of efficiency. Even with a small microwave and a very large inverter, you will blow one or the other if you match the wattage rating. <br /><br />It is the initial surge power that is the killer! Been there and done that, cha ching$$$$

 

[bubbakat]

Re: convert dc to ac ?

Thanks guys for the input.<br />Prob solved<br />Went and bought him a 12v micro-wave