SA 200 welder and ac power tool question

Talking to a welder friend of mine today and he mentioned that he was thinking of getting a generator to power up his grinders, mag
drill and other ac tools because the SA 200 only puts out dc volts and is tough on some ac tools. I suggested possibly setting up an invertor to run of the welders 12 volt charging system. It looks like most his stuff is in the 15-20 anp range from what I could see around his shop, so an invertor may work but i'm not sure if the charging system could handle it. What do you guys do out in the field away from ac?
Thanks for looking
Jeff
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I have a SA 200, and it seems to work AC power tools fine. I am not a whiz at electricity, other than to tell you if it's off or on, but I'm sure someone here will explain it in detail. When I got my SA 200 running, I asked this same question, and was assured it was okay to run the power tools.
Steve
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The DC output from the the SA 200 runs any 120 volt power tools with universal motors (those with brushes) just fine. That means drills, grinders, Skillsaws, and most hand held tools are good to go. This covers almost all the cleanup and fabrication tools used by welders.
You CANNOT run any machinery with split phase or cap start motors. This includes most larger compressors and table saws. Some of the smaller el-cheapo oil less compressors and smaller contractor style table saws use the brushed motors, they will run ok.
The only item that really gets to be a pain is compressed air: if you need air in the field, you are pretty much forced to get a gas engine driven compressor.
As for using an inverter: Running 12 volts in and 120 volts out means that the input current must be 10x greater than the output current (actually, more like 12X due to inefficiencies) So a 13 amp skill saw will draw 130 amps input, WAY more than the 12 volt output from the SA 200.
The inverters work ok for small loads like a small TV, computer, small 1/4" drill and similar.
jeff wrote:

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True, but the brush holder screws may not be obvious. The ones on my DeWalt look a lot like the other case screws.
The power rating is on the label. My angle grinders are clearly labeled for 120V DC or AC at 50/60Hz. Surprisingly the Dremel is labeled simply 120V AC, no mention of DC.
Jim Wilkins
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Jim sez, "Surprisingly the Dremel is labeled simply 120V AC, no mention of DC."
That is probably because the manufacturer (Dremel) assumes users of their tools will not have 110VDC supplies which will mate with their power cords. Universal motors (Dremels) are rated in RMS terms. Hook a Dremel up to 110VDC and it should run even better than on AC. All thing considered, Dremel brushes should last a little longer on DC.
Bob Swinney
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True, but the brush holder screws may not be obvious. The ones on my DeWalt look a lot like the other case screws.
The power rating is on the label. My angle grinders are clearly labeled for 120V DC or AC at 50/60Hz. Jim Wilkins
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Dremels commonly have speed controls, they don't work well on DC. Ditto any of the big routers with soft start controls.
Jim Wilkins wrote:

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RoyJ sez: "Dremels commonly have speed controls, they don't work well on DC. Ditto any of the big routers with soft start controls."
Good comeback! I would have to amend my statement to exclude some motors with speed controls as not being suitable for use on DC. That may be why Dremels only show AC as input current.
Bob Swinney
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Actually, I didn't even think about Dremel tools which are brushed but have the controls when I answered the original post. Somehow, I just didn't relate using a Dremel tool and an SA200 in the same sentence. :)
Robert Swinney wrote:

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Thanks to those who have replied. I spoke with Don, my welder friend and this is what he clarified for me. It would seem that he owns mostly Makita brand power tools because they seem to work properly AC or DC. The problem he is having is with the Milwaukee brands.. he keeps taking out the power switches. He spoke with a Milwaukee rep and was told the switches in Milwaukee tools are only rated for AC service ????? Milwaukee does make a different switch for their tools that will hold up and he is looking into that now.
He is still interested in the invertor option as well as ithis would take up a smaller footprint on the trailer that the generator is mounted on than a stand alone generator. This may not be the place to ask and I will follow up at some invertor dealers when I get a chance but it would seem that if a person installed a 185 amp or larger alternator on this welder then he could possibly run a 3000 watt invertor which may take care of his needs. The problem that this engine may not handle a larger alternator. His other option would be to mount the invertor on his service truck. I haven't seen it but he says that its a diesel and has two batteries. So many options. He should probably buy a generator and be done with it...
Thanks again.
jeff
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If you are that serious about needing AC power, consider running a belt drive 120/240 alternator off the front pulley. Here is a 7.2 kw unit for $300, less on sale. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?ItemnumberE416 It would really like a double v-belt drive but it will run ok on a 5L section single belt.
The continental engine won't even notice a 5kw load.
jeff wrote:

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Thanks Roy, That sounds like something that might work for him. I am just trying to give him options
Jeff
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wrote:

I have found all my Makita tools work fine if I just turn them upside down before starting to compensate for the AC to DC switch.
Steve
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Steve I'm gonna bite my tounge on my first reponse to ya as you seem to be a decent guy. I am not a welder but I do understand electricty and electronics. I do know that voltage and amp ratings are different for ac as opposed to dc as far as switch's are concerned.
If your telling me it really makes a difference in the manner you start your tools then I'll take that for what its worth to you.
thanks
Jeff
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wrote:

I thought by then you had received enough information to let you know that most tools are okay on DC. I'm sorry I forgot to put the smiley face, so here's one ..... ;-)
"It's a joke, son. A joke Ahhhhhh said." -Foghorn Leghorn-
Steve
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Only the tools that are marked AC/DC on the nameplate!

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Did you read the part where I said I have a SA 200 also and that normal AC tools work on it for me?
Steve
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Im rather familiar with this sort of stuff...and personally..Id mount the inverter on the service truck and take advantage of the amperage available from the two batteries.
Ive got a 3000 watt inverter on my big Ford van, dual batteries and so forth..and its a rather expensive one...runs even computers, nearly true sine wave output.
However...it WILL run the batteries down faster than the alternator can charge them, if you either overload it with too much load...or too many simultainious tools being used at the same time.
3000 watts wont run a very big air compressor, and the inverter had best be a very good one, else that huge starting surge will eventually let out all the magic smoke.
I also have a 6000 watt Heart inverter, came out of a rear pusher diesel land yaught that had been involved in a low speed head on with a bridge abuttment, and totaled.
The vehicle had a bank of huge 12vt batteries to run the inverter, and a monster 12vt alternator to charge them. Someone else got the batteries, damit...but I got the inverter, which is an interesting shelf filler, waiting the day until I get a big assed batch of 12vt batteries
Gunner
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The issue is that a switch to interrupt DC must be larger and different from a switch to interrupt AC, because AC goes to zero twice a cycle, while DC keeps on pressing.
Universal-wound motors could not care less, but switches do care, so if the manufacturer has specified AC/DC, they provided the larger switch, but if it says only AC, the switch probably will not last if used on DC.
Joe Gwinn
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