DC to AC power inverter to run electic tools?

[Soundguy]

I have a small inverter which I have used on my tractor. It only will handle small tools like a power drill.. and even then.. if you are drilling heavy material, it wants to load up unless you constantly lift it a bit to clear the bit.

I used it when adding some gates to my fence in the back of the property.. no where near power.. the drill was for the holes for the gate hinges. worked reasonably well.. though for something like a skill saw.. that is going to be a big inverter.. even the small ones are about 9-10 amps.. that is a 100 watt plus unit and I would want some free headroom there.

Quite a load.. I wouldn't use it with the tractor running for fear of smoking the alternator.. and without it running.. the 100 amp+ draw for even a 1200 watt inverter is going to be short order..... like running the starter... probably less than an hour uptime on a good large new hi-cap deep cycle battery.

The 2000 watt and 3000 watt inverters are going to be close in price to the sub-compact 1' x 1' propane and small gas powered gennies that are in the 3-4.5kwat range.



Soundguy

 

[ns_in_tex]

Bob, I will share my experineces.
I have been using a Tripp Lite 1200 watt power inverter on my pickup for over 5 years. Use it daily. Run a 1 HP air compressor, ETC for short periods of time. It will run a skill saw if blade is sharp & you don't bind the blade, otherwise will blow fuses fast. I wouldn't be without it.

Now for the good part. I recently bought a Coleman Powermate PMP1200 inverter for my grandson from "Kitchen & Home Gadgets" online, for 119.99. I think it had one of the higher surge ratings of any I found. Maybe 2600 watt. I tried it out by drilling about 25 ea. 1-1/4 holes in pine tree stumps about 12" deep with a ship augar. It didn't even get warm to the touch. My grandson has been using it daily to run a 1/2" Milwalkee Hawg drill for the last month, with no problems.
It comes with 2 year warranty.

It might help in your situation.

Multiply the amps of your 120 volt tool by 10 and that will be the approx amps you will be pull off your 12 volt battery.

10 amp tool = 100 amp off battery.

 

[5030]

Re: DC to AC power inverter to run electric tools?

I am not an electrician, but I wired my own shop and it's 3 phase and single phase.

I have a good friend who is an electrician and he has told me more than once that the rule of thumb is that an ac motor draws 5 times the starting amperage as the running amperage. That's called inrush amperage. An electric motor pulls it's maximum amperage at 0 rpm.

That means if your drill draws 3 amps, it pulls 15 amps at startup and during a heavy load situation.

The other item you have to take into account is whether the inverter is true sine wave or modified sine wave.

Synchronous motors like a shop vacuum must have true sine wave to operate. Modified sine wave current will cause them to overheat and burn out. Any motor that derives it's running rpm from Hz current is susceptible to burnout from modified sine wave current as is any solid state device like a computer or microwave.

The Tripp-Lite units are all TSW I believe. Vector units come either way. Normally, a TSW unit will be more expensive and have a lower power factor than a MSW unit.

Installing an inverter on a CUT could be a problem. Most units are not weatherproof and can't stand moisture infiltration. I believe Tripp-Lite makes a marine unit. That unit will be sealed against the elements as well as salt water corrosion.

The other problem is with a CUT, the amp hour rating of the starting battery is not that great. An inverter at full load, would wipe out a battery in short order. If the engine was running, you'd either overload the alternator or melt the fusible link. Most alternator's in CUT's aren't rated at more than 35 amps. Tractors as a rule, have much less electrical needs than say your pickup truck.

I have a friend that has an on-board generator that runs off his engine, I believe it's called an Ohmite. It provides around 100 amps of 110 vac. I think it cost about $600.00

Another solution is to trick the alternator into making 110 vac. You can commercially buy switching appratus that will isolate the alternator and cause it to produce 110 vac. I'll do some searching on the web and get som web sites.

 

[5030]

Re: DC to AC power inverter to run electric tools?

If you are interested, try: www.hehrpowersystems.com
They have a complete line of on-board generation systems with the addition of an on-board welder too.

 

[jpr62902]

Re: DC to AC power inverter to run electric tools?

Daryl (5030),

My head began to spin and I went into convulsions trying to understand all that. /forums/images/graemlins/confused.gif Sure sounds like you know what you're talking about.

I've thought about just adding a 12V cigarette lighter outlet to my tractor so I could then take the charger for my cordless tools with me. Part of the problem here could also be the type of cordless tools. I use Milwaukee's 18 volt series and very rarely do I have to reach for a corded tool anymore. They're pretty powerful units. Just my $.02.

 

[5030]

Re: DC to AC power inverter to run electric tools?

As far as knowledge, most of my experience with electrical comes from experience.

One thing about electrical, especially the 220 volt variety, if it leaks, you get knocked on your A**. A plumber, on the other hand, just gets WET.

12 volt systems won't knock you down, but a direct short will draw enough amperage to burn you.

Most on-board systems like the one on the website I posted will not run an induction motor. They will, however, run brush type motors and about every hand tool I have ever seen has a brush type motor.

You could use the lighter plug arrangement to charge your batteries. But it would probably be cheaper to purchase extra batteries like I did for my DeWalt 18 volt hammer drill and keep 2 charged up in case you have to work in the field.

 

[Bob_Skurka]

Re: DC to AC power inverter to run electric tools?

OK now I'm totally lost.

The little JD lawn tractor has an 18hp Briggs & Stratton engine, with a 1000 watt inverter (1500 watt surge) and two GFI outlets. JD recommends that the engine be running at full throttle when using the inverter. They advertise that it will run an electric hedge trimmer, a power drill and similar hand tools. So maybe it has a HD alternater stuck under that little tiny hood of that lawn tractor?

I was looking at a 1500 watt (3000 surge) Marine unit and mounting it inside a water proof tool box behind the seat of the tractor. Maybe I'll pass on the whole idea or maybe I'll need to check out upsizing the battery and upsizing the alternator?

I guess I just figured if the little JD lawn tractor could do it then so could one of my diesels? From what I can see on some of the other threads, the Kubota B2910 electrical systems are pretty weak so I was leaning on putting the inverter onto the NH TC24D. Or maybe I should downsize the inverter to a 1000 watt unit and only use if for running a 3/8ths Drill, a jig saw, and similar smaller power tools? But it sure would be nice to run my big Makita circular saw wherever I needed it.

As for battery operated power tools I have 18volt Ryobi and find they last a long time on modest jobs, but the little portable circular saw runs out of juice very quickly cutting things like plastic decking. I built a play house for my daughter (2 rooms and a deck, 7 windows, 2 doors, and SOON to have electricity) and found that I could cut the siding with the battery operated circular saw, but that was about it. The play house is a good 130' from the main house, and probably 100' feet from our swimming pool and the pool shed so either way I have long runs of electrical cord and the associated voltage drop of those long runs.

 

[5030]

Re: DC to AC power inverter to run electric tools?

The marine unit will be weather proof so I wouldn't mount it inside anything. Besides, it will need air movement over the heat sink to keep the power transistors cool. Under hood mounting would be better, preferably in front of the radiator so there is cool air flow, not hot. I don't know what the ambient rating for any particular unit is. That ambient operating temperature should be on the specification sheet. Exceeding the ambient temperature rating will either shorten the life of the unit, or fry it.

One thing about inverters, they aren't very efficient. That inefficiency equates into heat.

I don't know how JD sets up their inverter system, but the instruction for you to run the engine at WOT tells me that the inverter is sized for the maximum output of the alternator.

 

[5030]

Re: DC to AC power inverter to run electric tools?

Here is something to ponder...

Even though we rely on electricity for our basic needs...
No one has ever seen electricity....
Many people have felt it's effects though...
It's a common belief that electricity flows along the outer diameter of a given conductor.......
If the electrons actually move in the conductor, why dosen't the conductor shrink and eventually get used up............
That's why a stranded conductor is more efficient at delivering electricity, more strands mean more diameters....

 

[Bob_Skurka]

Re: DC to AC power inverter to run electric tools?

Daryl, I was going to mount it in the waterproof tool box, but in such as way that the box would have to be open to use the inverter, thus allowing the heat syncs access to air. I use an inverter in my Cherokee and know they need some air flow. My reason for mounting it in the box was to protect it from damage. I suppose I could also install a small low power computer type fan in there to increase the cooling.

I think I may try to dig up the specs on the electrical system of the John Deere tractor and see what the alternator size is, and how the inverter is actually set up.

I did not think of installing the inverter under the hood in front of the radiator, which on my NH would be right over the top of the battery, but if there is room, that would also be a good spot. I supposed I'd have to open the hood to gain access to the inverter, but that would certainly be a protected spot where it would not get damaged.