12 V DC to 120 AC inverter for field work.

[jmc]

Hello,

Anyone have experience running an AC skilsaw off a 12volt inverter? This saw is 15A@120V. Do they have reasonable power? Does either component burn out? Thanks,

John

 

[ultrarunner]

I've run a Statpower 2000 watt inverter in my service van over 20 years...

It will run a 15 amp skill saw if everything is set up right.

I use a skill panel saw 95% of the time which is less than half the draw and contrary to what everyone said... will cut 2x material all day...

You will need a quality inverter AND large copper cables AND sufficient battery power to make it work... I have a second RV batter set-up with a added continuous duty golf cart solenoid that allows both starting battery and second battery to be joined... like using jumper cables... only at the flick of the switch.

When I need to run near the max, I also keep the engine running which makes a lot of difference... also swapped out the stock alternator for one designed for ambulance service... still single pulley, 130 amp and pully for more power at lower speed.

I would think running a skill worm saw all day with a generator might make more sense if only to keep time off the engine.

 

[aczlan]

15 amps at 120v is 1800 watts. A inverter that size will run you $150-500. You would be better off getting a generator for $150 on Craigslist and putting that in your bucket or on a carryall.

Aaron Z

 

[ultrarunner]

15 amps at 120v is 1800 watts. A inverter that size will run you $150-500. You would be better off getting a generator for $150 on Craigslist and putting that in your bucket or on a carryall.

Aaron Z

I paid over a $1000 20 years ago~!

 

[aczlan]

I paid over a $1000 20 years ago~!

A 2000W continuous (3000W for 1 hour and 4000W for 10 Sec) Tripplite will set you back less than $500 (Tripp Lite PowerVerter® Plus 2000W Industrial-Strength Inverter with 2 Outlets (PV2000FC)). A Synergex from Westmarine will set you back $1000: SINERGEX PureSine2 Inverters, 12 Volt DC Electric Systems at West Marine

Aaron Z

 

[ultrarunner]

It's amazing how much prices have come down...

I bought mine at West Marine and at the time, the sine wave model was $2500...

Did learn one trick that I should mention...

On my inverter... it will go to sleep if there is no load... not a problem if starting a small load.

On a full load, it will trip the safety and show overload which requires turning off and then on to reset.

I have a 60 watt light bulb plugged into the other outlet and this draws enough to prevent sleep mode...

 

[k0ua]

15 amps at 120v is 1800 watts. A inverter that size will run you $150-500. You would be better off getting a generator for $150 on Craigslist and putting that in your bucket or on a carryall.

Aaron Z

Also don't forget that the inverter is not 100% efficient. It may be close to 90% when running at maximum load. Somewhat less with smaller loads. But lets say it is 90%, so the output side as Aaron pointed out is 15 amps * 120 volts=1800 watts. So .9X=1800 X=2000 watts on the input side. Now if we can maintain an actual 12 volts under this load, we would be lucky, so lets figure the approximate current draw in Amps. So E * I=P Volts * Amps = Power in watts.. 12 * I=2000.. solve for I.. equal 167 AMPS (rounded).. so that is a bunch of Amps. About like the starter on your tractor cranking all the while that saw is running. You need really big wire, really clean low resistance connections and a really good battery and enough time in between cuts for the alternator to catch up and recharge that suffering battery. Remember starting batteries are NOT designed to be run down, like stationary or marine service batteries are. Even one run down can shorten the life and reduce the capacity of a starting battery. In my opinion you would be better off with a small generator.

James K0UA

 

[BrandonR]

Let's do the math shall we..

Lets say you have the 60 amp alternator in your L4330,

That's 60 amps at 14 volts or about 840 watts output max, your skill saw draws 1800 watts at 120 volts, figure some overhead for the inverter and you're drawing around 1000 watts from the battery (80 amps or so) on top of what the alternator puts out.

Your tractor takes a 75amp-hour battery, it's only safe for the battery to draw half that power so you have about 500watt-hours to use before you have to stop working.

So with the engine running, starting with a completely topped up battery you can run the saw continuously for 30 minutes before you have to stop working, it will take at least 20 minutes (But most likely more) to top the battery back up once you do this though.

So in summary, cutting a few fence boards at a time and letting the tractor run in between it'll work just dandy but don't plan to sit down and cut for extended periods.

 

[BobRip]

Also don't forget that the inverter is not 100% efficient. It may be close to 90% when running at maximum load. Somewhat less with smaller loads. But lets say it is 90%, so the output side as Aaron pointed out is 15 amps * 120 volts=1800 watts. So .9X=1800 X=2000 watts on the input side. Now if we can maintain an actual 12 volts under this load, we would be lucky, so lets figure the approximate current draw in Amps. So E * I=P Volts * Amps = Power in watts.. 12 * I=2000.. solve for I.. equal 167 AMPS (rounded).. so that is a bunch of Amps. About like the starter on your tractor cranking all the while that saw is running. You need really big wire, really clean low resistance connections and a really good battery and enough time in between cuts for the alternator to catch up and recharge that suffering battery. Remember starting batteries are NOT designed to be run down, like stationary or marine service batteries are. Even one run down can shorten the life and reduce the capacity of a starting battery. In my opinion you would be better off with a small generator.

James K0UA

Good points, but remember the saw will not be pulling full current all the time. Let is startup unloaded and then cut gently. It still can be a lot of current of course. It might make more sense to get a battery power saw.

 

[BobRip]

Also don't forget that the inverter is not 100% efficient. It may be close to 90% when running at maximum load. Somewhat less with smaller loads. But lets say it is 90%, so the output side as Aaron pointed out is 15 amps * 120 volts=1800 watts. So .9X=1800 X=2000 watts on the input side. Now if we can maintain an actual 12 volts under this load, we would be lucky, so lets figure the approximate current draw in Amps. So E * I=P Volts * Amps = Power in watts.. 12 * I=2000.. solve for I.. equal 167 AMPS (rounded).. so that is a bunch of Amps. About like the starter on your tractor cranking all the while that saw is running. You need really big wire, really clean low resistance connections and a really good battery and enough time in between cuts for the alternator to catch up and recharge that suffering battery. Remember starting batteries are NOT designed to be run down, like stationary or marine service batteries are. Even one run down can shorten the life and reduce the capacity of a starting battery. In my opinion you would be better off with a small generator.

James K0UA

Good points, but remember the saw will not be pulling full current all the time. Let is startup unloaded and then cut gently. It still can be a lot of current of course. It might make more sense to get a battery powered
saw.