Feasability study

There are occasions when it would be handy to have a portable piece of equiptment that is used at a remote worksite that is capable of being
run from a 12VDC or 24VDC power source. I am aware that there are dc to ac power inverters but the ones i have looked at are pricey once you get into 5kw range. A portable generator is not desirable for my needs. High torque low voltage DC motors from industrial supply houses are cost prohibitive. I was pondering using a automotive starter motor for say running a small compressor, horizontal bandsaw, drill press etc.
This unit looks like it can be modified to accept a pulley by removing the bendix.
http://www.ebay.com/itm/370868870946
Anybody try this appoach? Results?
The max run time on the motor would be 5 to 10 min at a time. Will there be any issues with over heating the motor?
TIA.
Best Regards Tom.
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Automotive starters can only run for a very short time, 15 seconds to a minute. After that they overheat.
i
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If you can find a CASE brand "starterator", they are rated for continuous duty. They won't have as much torque as a starter-only motor, but they'll run off 12VDC indefinitely. I know of no 24V version.
But why modify junk? There are tons of universal motors out there in those voltage ranges. And why cobble something up by hacking a good device when you can just buy the motor for the purpose?
Have you considered DC servo motors? They're not free, but pretty cheap on the surplus and pull-out market. I have three HONKIN' big ones from a Bridgeport R2E4 CNC mill I'll sell you for $600 for all three.
Lloyd
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On Thu, 20 Mar 2014 07:29:51 -0400, "Jim Wilkins"

Duty: Intermittent. (just like a starter motor)
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On 3/20/2014 6:03 AM, Ignoramus28555 wrote:

Heard that. But isn't that because they are basically 6 volt motors running on 12 volts?
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On Thu, 20 Mar 2014 13:46:08 -0500, Richard wrote:

No. They're basically 12 volt motors that are designed for exactly the service that they usually provide: brief periods of operation at high torque, in between long periods of time where all they do is add weight and cost to the vehicle without contributing to its function.
(Well, and for being as cheap as humanly possible while still getting the job done.)
Operating one at 6V (or at lower torque output demands) may allow it to work longer, but it almost certainly won't be as good for a long-duration task as a motor that's designed specifically for continuous use at 6V.
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Starters are designed for high output and short cycle. the opposite of what you're after. You need continous duty.
look to surplus center or fleabay for cheap DC motors. Scrap golf carts are another great source.
Karl
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Broken power wheel chairs would be an excellent parts source if it weren't for government policies that can leave people dependent on grey-market repairs. I fixed them for a while, but wouldn't touch one now without an employer's insurance policy to protect me from liability.
https://www.aahomecare.org/press/medicare-policies-restricting-power-wheelchair-repairs-leave-vulnerable-beneficiaries-with-limited-mobility
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Here'a another good idea from the mobility industry: http://www.bruno.com/vehicle-lift-curb-sider.html
A do-it-yourselfer could omit the electrics and use a boat trailer winch to lift generators and air compressors into the SUV. I maximized the lift height of my truck bed crane by fitting a pulley into the end of the boom.
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On 20/03/14 09:04, azotic wrote:

A more likely candidate would be some of the Bosch GPA series motors as they're continuous duty rated 12V and 24V and upto 750W. A couple of part numbers are 24V 750W 0 130 302 001 and 0 0130 302 013 which might enable you to find and vehicle application so you might find one 2nd hand.
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wrote:

What source would you use, your truck?

What, specifically, do you want to run? What voltage, current, etc?
You can power a compressor with a lawnmower (or other cheap German) engine. http://tinyurl.com/ow26frz and http://tinyurl.com/pwfta67
I have a parallel bar setup to make a portable drill into a drill press. Like this: http://tinyurl.com/pmvuakz
I think a 1kw inverter will run a HF 8" drill press (2/5hp)
Have you considered a used generator?
How about gas powered tools, both 2 and 4-stroke? I've seen them converted to drive damnear anything, such as... http://tinyurl.com/yagk22g http://tinyurl.com/qjzcyqm

Yes, I'm sure there will be problems. They're designed for maximum power for short periods of time. Crank one for over a minute and they start getting really hot, even without a load.
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On 3/20/2014 2:04 AM, azotic wrote:

Dad used a starter motor with a flexible shaft and stone to sharpen the bits on the big circular saw in his portable saw mill. This was in the late 1940's and early 1950's. I don't think he ever replaced the motor. Probably a 6 volt motor. And was intermittent.
Current starter automobile starters are probably not useable, as others have said. However, starter motors, like on my 1997 Dodge diesel pickup don't run steady for a long time. I have had to replace the solenoid contacts because the arcing eroded them. That has been the only problem. As I recall, that motor is a 12 HP starter.
Find a truck starter and try it.
Paul
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On 03/20/2014 04:04 AM, azotic wrote:

Anyone know the voltage of treadmill motors? If appropriate for this use, used (rescued from discards) they should be cheap.
technomaNge
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