Generating 110v 15 Amps From Farm Tractor

Ahem - <...125 amps...> - shouldn't that be 13.64 amps for <...!500 watt...> at <...110v...>?

<...did not work...> The poor thing was almost certainly overloaded, and probably shut itself down to protect itself using internal overload protection circuitry.

<...is there a better way?...> Either a smaller microwave, or use the engine itself as the cooker with an intervening frying pan, would both work, as would a small campfire made of the material that the chainsaw has felled.

Who knows?

<unsubscribes>

You are barking the wrong tree, or barking up the wrong tree. Hard to see from here.

Generally speaking, the alternator provides about 13.4-13.8 volts at sufficient amperage to keep on board battery charged. The output from the battery is input to a power inverter. Usually, you want beefy wires from battery to inverter connection.

Your 1500 W inverter might only be 1425-1450 actual DC Watts. Your microwave states 1500 W, supposedly at 100% full power. Have you attempted operating the microwave at a lower power setting (if adjustable by control panel)?

Other than that, cook on wood.

Wouldn't work with any microwave that I have ever owned because reduced power cycles the MW on and off at full power.

Thanks tcmtech, nothing like having someone how has done it! I noticed that the Delco alternator you have been using is a 3 wire type. How does the wiring work on that? Fair amount of space for the larger battery. Should work.

As far as I know they work either way. The ones I have came with a plug on the side port where the extra two control wires went that can come out if the machine its going on need to use them for any reason.

If you're not sure about it when buying one just ask them specifically for the 1 wire version. Odds are it's the same one I linked to.

The alternator is used to charge the battery, it's the battery rating you need....the amp hour rating...a 100ah battery should operate a 1500 watt microwave for about 20 min if the battery is fully charged....also the wire size and length of run are both critical, they must be able to carry the load...check this calculator and you can see the length of run of the 12v wire changes the wire requirement dramatically...for a 100 amp load(min) and a 3' run you need #2 awg for 6' you need #00....so the shortest run possible to the inverter from the battery is recommended...now from the inverter to the microwave is only about 13 amps@ 120v and much smaller #14 awg can probably suffice...

http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

http://www.donrowe.com/power-inverter-faq-a/258.htm

You'll need more than 1500W in to get 1500W out - how much more will depend on the efficiency of the inverter.

Another highly likely scenario is that when you use your chainsaw powered by the tractor, the tractor is right there with you, as in near the chain saw. When you attempted to use the microwave, it was likely in the kitchen, whereas I doubt that you drove your tractor into the kitchen, so you used an extension cord. The microwave was going to draw the PEAK power of that inverter, so ANY voltage drop from the tractor to the kitchen on that extension cord was going to likely take the microwave out of commission. And the voltage drop would be made SUBSTANTIALLY WORSE if that extension cord was less than 12ga wire.

Actually a 1500 watt load on a 100 foot 14 gauge copper extension cord would only see about 6 volts drop from one end to the other.

At ~2.5 ohms per 1000 feet a 100 foot 14 gauge cord would have a total resistance of ~.5 ohms which for a 1500 watt load at 120 VAC that's a miserly ~ 6.25 volts loss which is only about 5% less than ideal and still well above the typical +- 10% of nominal rated voltage any properly designed appliance is supposed to work with.

Which BTW my old 1500 watt (VA actually) microwave is rated for a 115 VAC input not 120 VAC so at ~ 114 VAC it would be working near optimally and not actually operating a slightly overdriven condition.

The way I see it at worse even with a bit of under voltage and the square wave input he will still get his Hungry Man microwave dinner cooked. It just might take him 7 minutes instead of 6 but in the end he will live and the cat won't end up on the BBQ for him to do it!

Try running the microwave at 50% or less. This will determine if the modified sine wave output is the issue. If it works, then gradually increase the power level until it fails. Then you can determine what you want to do.

Depends on the device operation. Don't know about newer models, but with old ones (like my clockwork one) the heating control just sets the mark/space ratio for the ON time - e.g. 50% would be 10 sec on/10 sec off (repeated).

Even the newer microwaves that I have seen reduce power by varying the duty cycle exactly like you said.

Come to think of it, it's not a power reduction, it is a reduction in the energy delivered. Unless of course you were to specify average power

But the average consumer won't understand 50% energy delivered either.

Never mind.

Mine is the same way the power setting just reduces the time it's on and off according to the timer....for instance if you put it on 30% power it's on for 3 seconds and off for 7 sec, then just repeats that pattern until the timer runs its course....

Disregard post 10, sorry about that.

Is that 1500w the input or output power?

Microwaves are generally rated at output power, so your 1500w microwave will likely be drawing up to 50% more than that from the inverter.

Microwaves also have pretty poor power factor which makes them an even more difficult device for an inverter.

A 1500w microwave could easily draw in excess of 200 amps from a 12v DC supply, and maybe even more using a modified square wave inverter, no such thing as a modified sine wave inverter, they produce a square wave that is then modified to form shoulders.

All of the above means that neither your inverter nor your DC supply are sufficient in capacity to run said microwave. Running on low setting won't help either as a microwave controls its power by duty cycle, ie. as the settings are reduced, it still draws full amps when the Magnetron is energised, it's just energised for progressively shorter time periods

If he's in the US he's limited to 1500 watts or 1500 VA input on a 120 volt line that isn't hard wired in or uses a special service capacity plug which very few kitchen appliances do.

~83% of what a standard residential 15 amp circuit can handle by national code.

That and most every appliance manufacture inte US rates their products by input watts as well so if his says 1500 watts that's 1500 watts input even if the magnetron only puts out half that.

Thank you for that info.

Over here we can plug up to 2400w into a standard GPO, and then 3600w into a 15 amp rated one or 4800w into a 20 amp rated one, all of which have a similar configuration but with differing dimensioned pins to prevent the higher rated devices being used on the lower rated outlets although you can go vice versa.

Many of our 30 amp plus ovens and hotplates are now plugged into 15 or 20 amp outlets, relying on diversity calculations for loading.

Yea. Many years ago a lot of higher capacity devices were designed around 20 amp circuit capacities and came with 20 amp plugs on them and ratings up to 1800 - 2000 watts input but unfortunately too many people either bent the prongs to fit 15 amp sockets or put cheater adapters on the plugs or just replaced the plugs with 15 amp ones then tried to run them off 15 amp circuits.

Either they didn't work right due to constantly blowing fuses or tripping the breakers or people just switched out their 15 amp fuses and breakers with 20's even though their homes only had 14 ga wiring which started burning too many places down from it.

As of now finding any modern appliance or power tools with a more than 1500 watt input ratings and a factory equipped 20 amp plug on it cord is near impossible unless it's designed for a commercial application where it guaranteed that it will have a properly sized and designed electrical feed supplying it.

Now most everything in a residential application now that draws above 1500 watts on 120 volt power is expected to have dedicated hard wiring supplying it or just be 240 volt powered.

This will be interesting. The microwave I'm using is a Panasonic Inverter. It's claim to fame is that it actually delivers continuous energy at a lower output rather than switching on and off. I'll test it!