Stall current testing

[mbinsewi]

Is it still a good idea to test a loco that you want to convert to DCC ?  I wanted to do this to a couple of older Athearns but I'll be darned if I can remember the proceedure.  I know it involved a multi meter, and a DC power pack.

I'm taking the lazy way out here, as I haven't searched the subject yet to see whats out there.

Mike.

[peahrens]

You need to set the multimeter to current / ohms setting and put it in series on one of the powerpack leads to or from the track, so it can measure the current through the circuit.  Some meters have 3 probe connection points, one for common and two options for the other probe, depending on what type reading you need. I have one where one of the leads has to be inserted in the right "ohm" symbol / milliamp hole, versus another hole for high amps (10A) measurements.  Anyway, put it in series and get the polarity of the probes so that you get a positive reading.

I've acquired a number of DC locos for conversion to DCC.  Before diving in, I put the loco on my 4' test track to see if it runs reasonably.  I added an Ohm meter to also check the stall current, needing to assure the loco will not overload the decoder rating.  I use a MRC 1300 powerpack.  The setup includes a fuse that protects the powerpack in case I create a short.  I have added some current (ha!) photos.

https://www.ebay.com/itm/DC-2A-Analog-AMP-Current-Panel-Meter-Ampmeter-Ammeter-Gauge-85C1/192306321125?hash=item2cc65996e5:g:5ZoAAOSwgkRVSulK

 

 

[RR_Mel]

Any multi-meter with a current range of 2 amps or more will work.  I just put the meter in series between one rail and the power source.  I adjust the voltage to 12 volts then on a piece of test track I slowly apply pressure to the locomotive wheels against the rails until the motor stops.

 

If you have the shell off hold the motor shaft so that the motor doesn’t turn and apply 12 volts. 

 

The motor stopped with 12 volts applied is Locked Rotor Max Current.

 

DO NOT DO THIS FOR MORE THAN A MOMENT TO PREVENT BURNING UP THE MOTOR!

 

The Gold Athearn BB motors normally draw a bit over 1 amp at locked rotor.  The older grayish Athearn motors can draw close to 2 amps locked rotor.

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[mbinsewi]

Thanks guys.

Mike.

[richg1998]

Easy to do today. I use the below method with the same meters. It cost me more to make suitable probes with clips than the cost of the meters.

Few years ago the meters cost about two dollars each. Have four.

The meter front can be different.

http://www.trainelectronics.com/Meter_HF/index.htm

I remember doing this with the old analog meters.

Today, nice with auto polarity and auto ranging, though some multimeters do not auto range.

Rich

[peahrens]

richg1998

Easy to do today. I use the below method with the same meters. It cost me more to make suitable probes with clips than the cost of the meters.

Few years ago the meters cost about two dollars each. Have four.

The meter front can be different.

http://www.trainelectronics.com/Meter_HF/index.htm

I remember doing this with the old analog meters.

Today, nice with auto polarity and auto ranging, though some multimeters do not auto range.

Rich

 

That's a really cool setup, Rich! 

If I had known I would have copied it when I added my (McIntosh type) meter on the test track.    Maybe we should make & sell a test track setup.  I'd say we could make it for $15, so sell it for only that, plus $200 (oh, let's make it $400) shipping.