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Need some advice from a EE type [message #259622]

Thu, 21 August 2014 16:03

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

Some of you may remember the electric table I had in Montgomery.
http://www.gmcmhphotos.com/photos/g6475-table.html

It worked fine but took 3 minutes and 7 seconds to fully lift. Not optimal.

In my search for a faster solution, I ended up with a Harbor Freight 2500 lb winch. A bit overkill but it was cheap and certainly powerful enough.

Got everything wired up with the limit switches working and everything. The problem is that it is now TOO fast...8 seconds to be exact. I've gone to a double pulley system (think block and tackle) and that doubled the time from about 4 seconds in a straight pull. I could go to an additional set of pulleys but I'd rather try and slow the motor down.

This is a 1 HP (chinese HP) 12V motor on #10 wire with a 60A breaker in line....WAAY overkill. I put my AmpProbe on the hot wire and get 5 Amps when the motor is running. So here is the question. If I put a 'resistor' in the circuit, what would it take in terms of Ohms to slow the motor down by 50 ish% AND handle the 5 Amps. This is going to be very intermittent usage except when I'm showing off. That is to say, up, eat, down.

Comments and advice solicited. Even from (gasp) non-engineers.... Laughing

Laughing

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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Re: Need some advice from a EE type [message #259625 is a reply to message #259622]

Thu, 21 August 2014 16:21

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

Oh, forgot, variable speed would be nice too. Would something like this handle what I need?

http://www.amazon.com/RioRand-trade-Upgraded-6V-90V-Controller/dp/B00F839VNQ/ref=pd_tcs_subst_hi_2?ie=UTF8&refRID=0HKMRG21PRB2FXWA5TYQ

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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Re: Need some advice from a EE type [message #259630 is a reply to message #259625]

Thu, 21 August 2014 16:47

tphipps

Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL

Karma: 9

Senior Member

PWM controller should do the job. Resistor is not a recommended method. The item from Amazon appears to have the current handling capability for your motor control. For the price, worth trying.
Tom, MS II not an EE, just a Tech+

2012 Phoenix Cruiser model 2552 KA4CSG

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Re: Need some advice from a EE type [message #259634 is a reply to message #259622]

Thu, 21 August 2014 17:19

bwevers

Messages: 597
Registered: October 2010
Location: San Jose

Karma: 5

Senior Member

Yes, that PWM sounds like the way to go.
You would need a huge resistor. Something like 100watt rating, 3ohms for half speed....

Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose

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Re: [GMCnet] Need some advice from a EE type [message #259635 is a reply to message #259625]

Thu, 21 August 2014 17:19

k2gkk

Messages: 4452
Registered: November 2009

Karma: -8

Senior Member

For that price, what harm, Kerry!

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
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~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
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> Date: Thu, 21 Aug 2014 15:21:43 -0600
> To: gmclist@temp.gmcnet.org
> From: Pinkertonk@MCHSI.com
> Subject: Re: [GMCnet] Need some advice from a EE type
>
> Oh, forgot, variable speed would be nice too. Would something like this handle what I need?
>
> http://www.amazon.com/RioRand-trade-Upgraded-6V-90V-Controller/dp/B00F839VNQ/ref=pd_tcs_subst_hi_2?ie=UTF8&refRID=0HKMRG21PRB2FXWA5TYQ
> --
> Kerry Pinkerton
>
> North Alabama, near Huntsville,
>
> 77 Eleganza II, "The Lady", 403CI, Manny Brakes, 1 ton, tranny also a 76 Eleganza to be re-bodied as an Art Deco car hauler

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Re: Need some advice from a EE type [message #259637 is a reply to message #259625]

Thu, 21 August 2014 17:40

Keith V

Messages: 2337
Registered: March 2008
Location: Mounds View,MN

Karma: 0

Senior Member

that would be the way to go. you'll love it
I resister would be a real hack

Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com

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Re: Need some advice from a EE type [message #259641 is a reply to message #259634]

Thu, 21 August 2014 18:06

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

bwevers wrote on Thu, 21 August 2014 17:19

Yes, that PWM sounds like the way to go.
You would need a huge resistor. Something like 100watt rating, 3ohms for half speed....

I guessed abut 2.4 ohms and about 30 watts. I found a 2.2 ohm power resistor on the net that could handle 50W for $2.79 plus shipping. Might have worked, but I like the controller idea better.

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Re: Need some advice from a EE type [message #259642 is a reply to message #259622]

Thu, 21 August 2014 18:08

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

Ordered this PWM need to get/build a box

http://www.amazon.com/DROK-12V-40V-Electric-Controller-Stepless/dp/B00CGXJSNY/ref=pd_ybh_3

Thanks guys

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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Re: Need some advice from a EE type [message #259644 is a reply to message #259642]

Thu, 21 August 2014 18:10

94nubble

Messages: 275
Registered: July 2011
Location: Chesapeake VA

Karma: 3

Senior Member

Don't do it. Those things create a huge amount of heat. Best way to slow motor down is by gear reduction.

Tom McManus
1977 Royale
Chesapeake VA

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Re: Need some advice from a EE type [message #259647 is a reply to message #259644]

Thu, 21 August 2014 18:16

Harry

Messages: 1888
Registered: October 2007
Location: Victoria, BC CANADA

Karma: 3

Senior Member

What slows down a 12V heater motor?
Is there a rheostat of some kind that would work?
A dimmer switch?

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Re: Need some advice from a EE type [message #259649 is a reply to message #259644]

Thu, 21 August 2014 18:30

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

94nubble wrote on Thu, 21 August 2014 19:10

Don't do it. Those things create a huge amount of heat. Best way to slow motor down is by gear reduction.

Don't do What??
All of the modern autopilots are PWM drivers and they don't get hot.
With a PWM driver he can put a set of near limits so it slows to park.

I would like to go on, but this a square dance and the next tip is up.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: Need some advice from a EE type [message #259650 is a reply to message #259647]

Thu, 21 August 2014 18:32

Keith V

Messages: 2337
Registered: March 2008
Location: Mounds View,MN

Karma: 0

Senior Member

Harry wrote on Thu, 21 August 2014 18:16

What slows down a 12V heater motor?
Is there a rheostat of some kind that would work?
A dimmer switch?

blower motors are probably series wound, the winch is probably permanent magnet.
A resister would kinda slow it down, but you would also need a 100watt resister or better...

Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com

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Re: [GMCnet] Need some advice from a EE type [message #259667 is a reply to message #259622]

Thu, 21 August 2014 20:04

Ken Henderson

Messages: 8726
Registered: March 2004
Location: Americus, GA

Karma: 9

Senior Member

Kerry,

Using E=IR: R=E/I Since you've got E=12 and want I to equal about 2.5, R=
4.8, call it 5 Ohms.

What size? P=EI so since you want to drop 6 volts across that resistor,
P=6*2.5=15 Watts. Since you'll only draw that current for a very short
time, the resistor won't get very hot, so you can use a lower load rating.
Fact is, I think while we were talking this afternoon I saw two 10 Ohm,
10-15 Watt resistors in my junk box. Used in parallel, they'll meet
your requirement easily. I'll check tomorrow and let you know. I may even
have adjustable ones for fine tuning the speed.

Ken H.

On Thu, Aug 21, 2014 at 5:03 PM, Kerry Pinkerton
wrote:

> Some of you may remember the electric table I had in Montgomery.
> http://www.gmcmhphotos.com/photos/g6475-table.html
>
> It worked fine but took 3 minutes and 7 seconds to fully lift. Not
> optimal.
>
> In my search for a faster solution, I ended up with a Harbor Freight 2500
> lb winch. A bit overkill but it was cheap and certainly powerful enough.
>
> Got everything wired up with the limit switches working and everything.
> The problem is that it is now TOO fast...8 seconds to be exact. I've
> gone to
> a double pulley system (think block and tackle) and that doubled the time
> from about 4 seconds in a straight pull. I could go to an additional set of
> pulleys but I'd rather try and slow the motor down.
>
> This is a 1 HP (chinese HP) 12V motor on #10 wire with a 60A breaker in
> line....WAAY overkill. I put my AmpProbe on the hot wire and get 5 Amps
> when
> the motor is running. So here is the question. If I put a 'resistor' in
> the circuit, what would it take in terms of Ohms to slow the motor down by
> 50 ish% AND handle the 5 Amps. This is going to be very intermittent
> usage except when I'm showing off. That is to say, up, eat, down.
>
> Comments and advice solicited. Even from (gasp) non-engineers.... :lol:
> --
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach

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Re: Need some advice from a EE type [message #259669 is a reply to message #259622]

Thu, 21 August 2014 20:19

bwevers

Messages: 597
Registered: October 2010
Location: San Jose

Karma: 5

Senior Member

Let's see, the winch was drawing 5 amps from 12 volts = 60 watts.
If you use ~double the size resistor wattage you should be safe.
But the PWM thing sounds better....

Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose

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Re: [GMCnet] Need some advice from a EE type [message #259676 is a reply to message #259625]

Thu, 21 August 2014 20:39

Ken Henderson

Messages: 8726
Registered: March 2004
Location: Americus, GA

Karma: 9

Senior Member

Yes indeed! That's a much better choice than using a resistor, for a lot
of reasons. But I'll still send you the resistors 'cause they should get
there sooner and, if they fill the need, they're all that's necessary.
PWM may be overkill.

Ken H.

On Thu, Aug 21, 2014 at 5:21 PM, Kerry Pinkerton
wrote:

> Oh, forgot, variable speed would be nice too. Would something like this
> handle what I need?
>
>
> http://www.amazon.com/RioRand-trade-Upgraded-6V-90V-Controller/dp/B00F839VNQ/ref=pd_tcs_subst_hi_2?ie=UTF8&refRID=0HKMRG21PRB2FXWA5TYQ
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach

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Re: Need some advice from a EE type [message #259678 is a reply to message #259622]

Thu, 21 August 2014 20:45

midlf

Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)

Karma: 1

Senior Member

Kerry Pinkerton wrote on Thu, 21 August 2014 16:21

Oh, forgot, variable speed would be nice too. Would something like this handle what I need?

http://www.amazon.com/RioRand-trade-Upgraded-6V-90V-Controller/dp/B00F839VNQ/ref=pd_tcs_subst_hi_2?ie=UTF8&refRID=0HKMRG21PRB2FXWA5TYQ

First question - Does your Amprobe have DC ranges? Most old ones don't. If yours does not have a DC scale any reading is bogus and probably is ripple on the DC current.

If your meter does have DC settings then the controller you found will work. Now be aware, this motor is essentially unloaded. If your limit switches ever fail this motor may try and head for a high amperage and rip the table apart. I would put a 20 or 30 amp fuse on it instead of the 60 amp breaker. If you wanted to use a breaker I would use a 15 amp. JWIWD

Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

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Re: [GMCnet] Need some advice from a EE type [message #259679 is a reply to message #259676]

Thu, 21 August 2014 20:47

Keith V

Messages: 2337
Registered: March 2008
Location: Mounds View,MN

Karma: 0

Senior Member

well a 'benefit' of the resistor is it will reduce the motor torque as well as slow it down so it won't destroy stuff when it hits a limit.

Not normally what you want in a speed controller, but maybe in this case.

Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com

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Re: Need some advice from a EE type [message #259680 is a reply to message #259622]

Thu, 21 August 2014 20:49

midlf

Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)

Karma: 1

Senior Member

Kerry Pinkerton wrote on Thu, 21 August 2014 16:21

Oh, forgot, variable speed would be nice too. Would something like this handle what I need?

http://www.amazon.com/RioRand-trade-Upgraded-6V-90V-Controller/dp/B00F839VNQ/ref=pd_tcs_subst_hi_2?ie=UTF8&refRID=0HKMRG21PRB2FXWA5TYQ

First question - Does your Amprobe have DC ranges? Most old ones don't. If yours does not have a DC scale any reading is bogus and probably is ripple on the DC current.

If your meter does have DC settings then the controller you found will work. Now be aware, this motor is essentially unloaded. If your limit switches ever fail this motor may try and head for a high amperage and rip the table apart. I would put a 20 or 30 amp fuse on it instead of the 60 amp breaker. If you wanted to use a breaker I would use a 15 amp. JWIWD

Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

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Re: Need some advice from a EE type [message #259797 is a reply to message #259622]

Fri, 22 August 2014 21:14

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

Steve, my meter does not have DC Amps so who knows what I was reading Embarassed

Embarassed

However, sometime around 2am, I woke up and realized my fancy pulley system was wrong and doing exactly nothing. Embarassed

Embarassed

So when I woke up for real, I pulled out the pulleys and started over. The result is a 50% reduction in speed. It now is about 15 seconds which is fine. Not so fast that it's going to hurt anyone but slow enough that you don't have to wait. I'll try the PWM when it comes in but I'm OK with it as is.

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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Re: Need some advice from a EE type [message #259799 is a reply to message #259797]

Fri, 22 August 2014 21:38

midlf

Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)

Karma: 1

Senior Member

Kerry Pinkerton wrote on Fri, 22 August 2014 21:14

Steve, my meter does not have DC Amps so who knows what I was reading

However, sometime around 2am, I woke up and realized my fancy pulley system was wrong and doing exactly nothing. So when I woke up for real, I pulled out the pulleys and started over. The result is a 50% reduction in speed. It now is about 15 seconds which is fine. Not so fast that it's going to hurt anyone but slow enough that you don't have to wait. I'll try the PWM when it comes in but I'm OK with it as is.

I believe what you are reading is ripple in the DC current. No telling what the real DC current is. You could try to measure the current draw with a standard direct reading auto ammeter. I would not use the pwm controller on it until you have a better idea of the real current.

If you look on fleabay you can find some multimeters that have AC/DC clamp on ammeters for a reasonable cost, about $35.

If you haven't got a read on it by Chippewa Falls see me as I will have my DC clamp there.

Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

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