LumberJocks

I need some electrical advice from the experts.

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by ohtimberwolf posted 06-14-2018 12:14 AM 1105 views 0 times favorited 8 replies Add to Favorites Watch
View ohtimberwolf's profile

ohtimberwolf

862 posts in 2497 days


06-14-2018 12:14 AM

Topic tags/keywords: microwave 700 watt truck question

I’m not sure where I might be supposed to post this so forgive me if it is in the wrong place.

I have a 750 watt inverter and I want to use it on the microwave at the site below. It says it is a 700 watt microwave but when I look on the back of the unit it says 1025 watts. My question is this, which wattage should I use to know if it will work with my 750 watt inverter as I want use it both in my shop and my truck.

Here is the link. https://www.walmart.com/ip/Mainstays-700W-Output-Microwave-Oven/54189709

larry

-- Just a barn cat, now gone to cat heaven.


8 replies so far

View msinc's profile

msinc

521 posts in 648 days


#1 posted 06-14-2018 12:41 AM

It sounds like you need 1025 watts of power to operate the oven and it will produce 700 watts of microwave cook power. You cant get more or even the same out of something than what you put in. The magnetron {the device that actually creates and shoots out the microwaves} is using 1025 watts to produce the working 700 watt microwave, which sounds about right.
As to the inverter…you have to be careful there too. They rate them in watts or sometimes “volt amps” which is just another way of saying watts. They are typically rated with two figures, a surge amount it can produce initially for a very short period of time and a constant amount that is usually quite a bit less. I have one generator that is advertised and a 7500 watt machine, but that is surge and it wont even do that without tripping. It will go to about 7000 and the constant amount is 5500. I have another one that is a Honda inverter. It is rated at 6500 constant and it will absolutely do it. it will surge higher, but never has had to. It just depends on the machine, who makes it and how they advertise the output.
If 750 is the constant on your inverter then I would try it, it might work and be fine, but the numbers are up there where if it sounds like it is really straining to get going and does not “unload” then I wouldn’t push it and just get a bigger inverter.

View ohtimberwolf's profile

ohtimberwolf

862 posts in 2497 days


#2 posted 06-14-2018 01:17 AM

Thanks msinc, advice well taken. I just was not that familiar with the tricky way it was put in the advertising. I’ll check the inverter but it doesn’t sound good to me, sounds more like I would be risking a problem. larry

-- Just a barn cat, now gone to cat heaven.

View CaptainKlutz's profile

CaptainKlutz

487 posts in 1639 days


#3 posted 06-15-2018 01:14 AM

Challenge with any appliance is that the panel rating is an averaged continuous measurement while running. It is not peak demand. Peak demand is almost never disclosed on appliances as it varies based on installation conditions. Does not help that house hold nominal voltage is 120V, but can vary +/- 20%. This makes the actual volt/amps values change. Often the watts required for a machine will not change, hence the 1025 watt panel rating.

As msinc stated, Inverters are tricky.
Ignore the marketing label on package. The data are usually honest if you read specification sheet, and will state recommended max continuous watts, and max peak demand for given ambient environment.

When using a 12V inverter, be aware that power conversion generates heat. If you try to run the inverter in hot environment, then power rating is usually reduced, or duty cycle can be lower. If I wanted to regularly use that microwave in a vehicle anywhere/anytime, would not attempt it with less than 1500 watt continuous rated inverter.
Another data point is that 1000W demand on car battery is equivalent to leaving you head lights on. Unless car is running, battery will limit appliance use to only <20 minutes between charging. Typically when using more than 300-500W of 120V inverter power in a vehicle, it is recommended to install a second battery with isolation to avoid a dreaded no start due dead battery.
When it comes to having 120Vac power inside vehicle, there are massive number of OEM and aftermarket possibilities, too many to describe.

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View ohtimberwolf's profile

ohtimberwolf

862 posts in 2497 days


#4 posted 06-15-2018 11:10 PM

Thanks for the info guys. Here is what I bought but could still return to HF.

It would only be used for heating a sandwich or cooking a couple eggs or heating some liquid such as a gravy or warming a drink. Do you think that would be ok for this unit or should I take it back? larry

https://manuals.harborfreight.com/manuals/69000-69999/69660.pdf

-- Just a barn cat, now gone to cat heaven.

View MrUnix's profile

MrUnix

6931 posts in 2343 days


#5 posted 06-15-2018 11:17 PM

That is too small. As mentioned above, you should get something at least 1200 watt continuous and 1500 or larger would be even better. Most microwaves run in the 600-1200 watt OUTPUT range, which is not the same as what it needs for power INPUT. If yours says it takes 1050 watts INPUT, then you need something that will supply 1050 watts continuous at the very least (and that would be marginal as you typically want to run 80% or less of capacity).

Update: According to the manual for that microwave, it states it needs 12A @ 120V to operate, so that means 1440 watts of input power (not just 1050). Based on that, I agree with the above – a 1500 watt inverter would be the smallest I’d go.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View ohtimberwolf's profile

ohtimberwolf

862 posts in 2497 days


#6 posted 06-16-2018 12:06 AM

Thanks Brad, I’ll take it back. Mansfield HF is only 34 miles from me. That is only a 68 mile mistake. :)

larry

-- Just a barn cat, now gone to cat heaven.

View msinc's profile

msinc

521 posts in 648 days


#7 posted 06-16-2018 12:32 AM


.............That is only a 68 mile mistake. :)

larry

- ohtimberwolf

You gotta get your mind right….a “68 mile mistake” is one way of looking at it….not burning down the house or garage is another, just sayin’

View ohtimberwolf's profile

ohtimberwolf

862 posts in 2497 days


#8 posted 06-16-2018 01:11 AM

msinc, you got that right!!!

-- Just a barn cat, now gone to cat heaven.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com