Solar rookie seeks help with 15-amp miter saw

jackypaper · March 2017

Hello, friends. I've been chatting with BB., who has been gracious in his responses when helping this solar n00b with beginner-level questions. He suggested that I post here.

My goal: To operate a 15-amp saw with solar power

My current set-up: Two 100-watt panels --- SunSaver 20L Controller --- two 6-volt series-connected Tojan T-105s --- 450-watt inverter.

My plan: Simply replace the small inverter with a 3000-watt inverter to provide for the saw's needs of 1800 continuous watts and 3600+ watt start-up

My questions: (1) Is running that saw for extremely short periods of time (like, two seconds per cut) possible with a 12-volt system? (2) If so, how large of an inverter is required? (3) Do I need a 24-volt system instead if I hope to run that saw at all?

Thank you all so much for taking the time to help a solar-power beginner.

jonr · March 2017

If it has a universal motor, it should work to add a 15A dimmer. This would allow a softer start and far less startup amps.

westbranch · March 2017

I usually use my 3000W genset with the sliding miter-saw, but tried it on the 2000W generator last week (continuous 1600W ) and it would suck wind every time I spun it up... so it will put a big drain on your 2 small batteries in all likelihood.... use the genny if you have one... and yes, 24 Volt... Look at the Exelteck inverters 2000W/4000 surge

Raj174 · March 2017

It would be cheaper and more practical to get a 3500 watt generator.

Estragon · March 2017

For this application, you might want to consider using AGM automotive starting batteries instead instead of deep cycle. Starting batteries have thin plates with lots of surface area for short bursts at high discharge rates. Don't draw them down deeply though.

Photowhit · March 2017

jackypaper said:
My goal: To operate a 15-amp saw with solar power

I'm going to work with this and assume you understand that this isn't cheap or most practical.

jackypaper said:

My plan: Simply replace the small inverter with a 3000-watt inverter to provide for the saw's needs of 1800 continuous watts and 3600+ watt start-up

What makes you think that there will be a 3600 watt + startup?

It is very likely a saw spinning up will not be the maximum load, it will likely be <1500 watts with a peak load when cutting into hardwood and binding. I have started my Table saw on an 1800 watt inverter (Prosine with a 2900 watt peak), it's a Delta pulley driven, I think rated as 15 amp.

jackypaper said:

My questions: (1) Is running that saw for extremely short periods of time (like, two seconds per cut) possible with a 12-volt system? (2) If so, how large of an inverter is required? (3) Do I need a 24-volt system instead if I hope to run that saw at all?

I think you have a good grasp. I think you could likely run a smaller inverter, pure sine for 2 second cuts on a 12 volt system. Perhaps even on just your 2 T105's. Your challenge will be in voltage drop. Thick wires (4/0) cabling between the batteries and to the inverter and very short distances. I think it's possible for short 2 second cuts.

Another Option;

I'm not sure about your needs and desires here, If it's to be able to make some cuts from a 12 volt DC system I would offer a cheaper option than a 1800-2000watt pure sine inverter.

Buy a Used DeWalt 18 volt saw, plan on the batteries to be dead but be sure to find one with a charger. <$100 used Buy the newer 6 1/2", buy a couple 2000Ah aftermarket pod batteries from Amazon $60. The chargers produced after 2000 will even work on a square wave inverter (some of the earlier ones don't)

I framed up an 'A' frame with the old trim saw (smaller 5 3/8th") I had a solar supply much like what you have and purchased a new drill and saw kit in 2001. They are limited, but less so than 2 second cuts.

jackypaper · March 2017

Raj174 said:

It would be cheaper and more practical to get a 3500 watt generator.

You know, this might end up being the better option.

jackypaper · March 2017

jackypaper said:

My plan: Simply replace the small inverter with a 3000-watt inverter to provide for the saw's needs of 1800 continuous watts and 3600+ watt start-up

What makes you think that there will be a 3600 watt + startup?

Thanks for your reply!

From what I've read, I assumed that an 1800-watt saw would require at least twice that amount for its initial start-up. Is that not accurate?

Photowhit · March 2017

jackypaper said:

jackypaper said:

My plan: Simply replace the small inverter with a 3000-watt inverter to provide for the saw's needs of 1800 continuous watts and 3600+ watt start-up

What makes you think that there will be a 3600 watt + startup?

Thanks for your reply!

From what I've read, I assumed that an 1800-watt saw would require at least twice that amount for its initial start-up. Is that not accurate?

It's not under load, for something like a compressor it's under a large load and making that first cycle is it's largest load. I don't "know" but would think it's unlikely. You wouldn't happen to live in Missouri? ExelTeck 1100 watt inverter will start and run my 12 amp chainsaw, I do it regularly. Exeltech will clip it's wave to run higher wattage items at a different power factor (I don't understand how that works, but it does.

I do worry that it would be frustration only being able to make short run cuts. I like the idea of using the solar to power the tools, and would hope you will consider the DeWalt Power tool option. People are moving to the newer lithium powered tools which makes a lot of sense, but the older pod battery tools can use the lithium batteries with an adapter and can be found very cheap now. I did a quick search on Craigslist and found a new set in KC MO drill, circular and recip 1 battery and charger for $125 and a saw and battery and charger for <$90 in St Louis. likely most pawn shops would have them as well.

oil pan 4 · March 2017

I run a skill saw and mig welder off my samlex 2000w pure sine 12v input inverter off my 72ah LiFePO4 battery. It works fine.

jackypaper · April 2017

Just as a follow-up, in case anyone is interested, I'm now successfully running my 15-amp miter saw off of two 6-volts and a 2500-watt inverter. It's a thing of beauty . . .

Photowhit · April 2017

jackypaper said:

Just as a follow-up, in case anyone is interested, I'm now successfully running my 15-amp miter saw off of two 6-volts and a 2500-watt inverter. It's a thing of beauty . . .

Good deal!
Mostly during the day with the solar producing?

jackypaper · April 2017

Photowhit said:

jackypaper said:

Just as a follow-up, in case anyone is interested, I'm now successfully running my 15-amp miter saw off of two 6-volts and a 2500-watt inverter. It's a thing of beauty . . .

Good deal!
Mostly during the day with the solar producing?

Correct. I've powered my fluorescent lights and stereo at night, but I put a strain on the batteries with the saw only during the Texas sunshine.

BB. · April 2017

Very happy to hear that this is working well for you.

Take care,
-Bill

s3w47m88 · November 2020

Hey @jackypaper I'm in an identical situation. Did you end up getting a 24v inverter and that solved the issue?

s3w47m88 · March 2021

I have a similar setup - here's a visual diagram of what I have: https://miro.com/app/board/o9J_lP4KTdE=/

Six 100 watt Renogy panels in Parallel.
Four 6v 200Ah batteries. Two Trojan T-105's and two Duracell's in series and parallel for 12v 400Ah.
One GoWise Pure Sine Wave 3000/6000w 120v inverter (25/50 amps?).
One 40Amp Renogy Rover Solar Charge Controller.

Even when I have nothing but the DeWalt 15Amp compound miter saw plugged in the inverter shuts off. I understand there is "inrush" which I thought was the same thing as "surge power", but I can't seem to get a definitive explanation of what needs modified with my system to accommodate for this. Been months, would really love some guidance! Thank you!

Marc Kurth · March 2021

What is the DC voltage on the inverter input when the saw tries to start?

Solar rookie seeks help with 15-amp miter saw

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