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tundrawolf
Starting Member
3 Posts |
 Posted - 07/20/2010 : 11:59:41
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Good day,
I am embarking on an oil priming system for an aircooled VW Beetle. I have a rotary gear pump that will pre-pressurize the oil system before the engine is started. (When the ignition is activated) I need something that will turn the rotary gear pump. The rotary gear pump head is a 1750 RPM unit that requires 1/3HP to achieve 100 PSI.
A 12V motor that produces 1/3HP is very large, and very expensive. (About $300) I want to use an inexpensive scooter motor.
My question is, with a 24V (Or even 36V) motor, how hard would it be to achieve a wattage draw of 250 watts? 200 watts?
Watts x .001341 = HP
So to achieve 1/3 HP I would need approximately a 250 watt motor, at 12 volts DC.
I guess my question is, what does a 24V motor draw current wise when hooked to 12 volts DC? |
Edited by - tundrawolf on 07/20/2010 12:01:32 |
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Uncle D
Journeyman Modder
Kailua Kona
H
USA
483 Posts |
Posted - 07/20/2010 : 13:38:12
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If no one has an answer right away I could check for you. I think amperage draw can be checked with a decent digital multimeter right? and with no load or what?
I just found this.
http://www.ehow.com/how_5073254_measure-amps-digital-multimeter.html
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Edited by - Uncle D on 07/20/2010 13:38:52 |
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gameboy
Administrator
just north of austin
tx
USA
1464 Posts |
Posted - 07/20/2010 : 14:19:04
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interesting idea, i like the way you think.
if your just looking for rpms, you could also get a 3000 rpm 24v motor and run it at 12v that would give you around 1500 rpms. thats close to 1750 rpms. |
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Uncle D
Journeyman Modder
Kailua Kona
H
USA
483 Posts |
Posted - 07/20/2010 : 15:14:55
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I think that's what he's getting at but wants to know what the "draw" of that motor is when ran at 24V. But isn't it hard to really say unless you knew what the load of that pump was on the motor to be used as the "draw" is dependent upon "load".
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timmy2time
Journeyman Modder
401 Posts |
Posted - 07/20/2010 : 15:50:54
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MODEL: MY1016 motor by Unite Motor Co. Ltd.
TYPE: Brush
VOLTAGE: 24 Volt DC
RATED SPEED: 2600-2850 RPM
RATED CURRENT: 13.5-13.7 Amp
SPROCKET: #25 Chain
OUTPUT: 250 Watts
On 12 volts: 125-150watts or 1/4HP and only about 1400rpm
This motor is 1/3HP on 12volts and TNCscooters.com has them for $58:
MODEL: MY1020
TYPE: Brush
VOLTAGE: 24 Volt DC
RATED SPEED: 2500 RPM
RATED CURRENT: 27.4 Amp
SPROCKET: #25 Chain 11 Tooth
OUTPUT: 500 Watts
But the rpm would be about half; 1250rpm
As far as the amp draw on 12volts, it all depends on the load.
Whats the deal with 1750rpm unit? It has gears? Is it a gear reduction unite? Or is it 1:1 ratio with the motor rpm? |
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tundrawolf
Starting Member
3 Posts |
Posted - 07/20/2010 : 17:38:18
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You guys are great. I appreciate the help. The pumps "ideal" specs I believe are 1750 RPM, with 1/3HP to achieve 100 PSI. I do not have to have 100 PSI, I just want the oil to reach all of the galleries and pressurize the system prior to starting. Right now, I don't even have the head, so I can't say for sure what will happen at 2000 RPM or 1/8HP, or whatever. I would ideally like it to be as close to 1/3HP at 1750 RPM as possible, at 12 volts.
I am also assuming that the current draw at 12V is indicative of horsepower. I might be totally off there, though.
Uncle D, to measure current, you use the multimeter as a "wire".
Set it to "Amps", and remember most multimeters will need the probe connection to be switched, usually the red probe, sometimes both red and black. Connect the red probe to the + terminal of your battery, and the black probe to the + wire of the motor, then the - terminal of the battery to the - wire of the motor.
But check the meters rating. I might be looking at a current draw of 30 amps, most meters don't go past 10 amps. You could blow a fuse or damage your meter if the current spikes too high over the rating. I am not sure if I am looking for full load amps or no load amps? |
Edited by - tundrawolf on 07/20/2010 17:44:51 |
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timmy2time
Journeyman Modder
401 Posts |
Posted - 07/21/2010 : 05:18:26
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| Where is the 1750rpm? At the motor shaft or...? You said it is geared. It might be a gear reduction. If so then putting a motor that revs to 1750rpm, the rpms will be wrong. |
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tundrawolf
Starting Member
3 Posts |
Posted - 07/21/2010 : 09:10:13
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| I see what you are saying. There is no gear reduction in the head. It is called a gear pump because as two gears mesh inside it creates a vacuum for pumping liquid. The manufacturer specifies a shaft speed of 1750 rpm. |
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Uncle D
Journeyman Modder
Kailua Kona
H
USA
483 Posts |
Posted - 07/23/2010 : 06:00:58
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I was gonna test it today but I noticed my DMM is only good for 10A I believe so I didn't test as I didn't wanna mess up the DMM or blow the fuse.
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JoeStud
Journeyman Modder
rochester
ny
USA
176 Posts |
Posted - 07/23/2010 : 23:29:21
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* Gonna try using a HD relay?
* Also... isnt there a way to utilize a used 12v starter motor?
* Lastly, is there a way to electrically interlock things, so that when the ignition is turned, the oil pump has to run for 15 seconds before the starter will crank? That way the oil gets circulated before starting the engine? 15 second timer (delay) relay in series with the starter motor?
Just brainstorming here.
***The Main Difference Between Men & Boys, Is Their Toys (Scooters)*** |
Edited by - JoeStud on 07/23/2010 23:35:01 |
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Topic |
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I need help with 24 volt motors
