DCC Operating Voltage for G Scale Locomotives

[LGB333]

A hobbyist contacted me recently with some operating issues with his new LGB 20581 F7A Santa Fe Diesel with the MSD3 mfx/dcc/analog sound decoder. He uses an MRC dcc 10 amp prodigy elite command station which outputs 15 volts. I stated that LGB locomotives require 18 - 22 volts DCC for optimum operation but he states: "I have not had any problem with the power supply that I am using. There have been times I have run the LGB 50th anniversary steam locomotive with the new Bachmann 4-6-0 steam locomotive with no problems."

For you engineers that have more electrical technical savvy than me, what operating problems can occur when using a lower-voltage DCC system for G scale locomotives, particularly multiple two-engine LGB locomotives?

 

[PhilP]

As long as there is 6V to wake up the electronics, then anything that and above should run, all-be-it, slowly..

With 15V you won't have the same top-speed, but it will run fine.

PhilP

 

[Greg Elmassian]

There are DCC compatible sound cards that need 12v, most trains will run fine.... the LGB track cleaning loco won't have enough voltage to spin the cleaning wheel well.

Aristo 3 axle diesels (and the GP40) will run very slowly.

The prodigy elite outputs 14.5 volts DCC.... the 15-16 volt spec is the DC input voltage, not DCC to the rails.

page 3 of the manual:

https://www.modelrectifier.com/v/vspfiles/resources/dcc/0001417manual.pdf

Greg

 

[LGB333]

There are DCC compatible sound cards that need 12v, most trains will run fine.... the LGB track cleaning loco won't have enough voltage to spin the cleaning wheel well.

Aristo 3 axle diesels (and the GP40) will run very slowly.

The prodigy elite outputs 14.5 volts DCC.... the 15-16 volt spec is the DC input voltage, not DCC to the rails.

page 3 of the manual:

https://www.modelrectifier.com/v/vspfiles/resources/dcc/0001417manual.pdf

Greg

Thanks for the correction...........so the DCC output to the rails is not even a full 15 volts. I note their Manual states "for all scales."

 

[LGB333]

As long as there is 6V to wake up the electronics, then anything that and above should run, all-be-it, slowly..

With 15V you won't have the same top-speed, but it will run fine.

PhilP

You and Railway42 posted in 2015 the following information about the Buhler motors used in LGB locomotives.

PhilP: The problem is not 'normal' running, but something called the 'stall current' of the motor.. As you increase the load on the motor (going up an incline, round curves, more rolling stock in our cases) the load on the motor increases. you get to a point where the motor stalls, and maximum current is drawn at this point. This is mainly due to the low internal resistance of the windings (long thin length of wire), and the energy not being used to turn the motor, and the load on the motor fighting back. A Buhler motor will run quite happily at about 0.2A with no load. Stop it spinning (stall it), but not for long it gets hot, and this can increase to 3Amps plus.

Railway42: Buhler 1.13.021.302 is the motor 24 volts power 6.3 torque 2 speed 3000 No load speed 4500 No load current 0.05 Stall torque 6.5 Stall current 1.3 Amps max. Taken from Buhler motor sheet. Burn one pole by misuse and you have 6 pols and 2-3 Amps ???

I'm trying to fully understand the electrical implications to LGB locomotives since I only sell, support, and DCC convert LGB locomotives. Everyone has said there's no problem with the DCC 14.5 volts output to the track other than they can't run as fast, or, as Greg points out, the LGB Track Cleaning Locomotives won't operate well. My question: Can an LGB motor become damaged, or lessen its operating life, by using a lower output DCC system considering the above comments on stall current and the motors are spec'd for 24 volts, for example, using the MRC dcc 10 amp prodigy elite command station which outputs 14.5 volts DCC to the track?

Thanks!

 

[Neil Robinson]

My question: Can an LGB motor become damaged, or lessen its operating life, by using a lower output DCC system considering the above comments on stall current and the motors are spec'd for 24 volts, for example, using the MRC dcc 10 amp prodigy elite command station which outputs 14.5 volts DCC to the track?

Thanks!

In short no. DC motor voltage is directly related to motor speed. As an iffy analogy consider a motor car with an advertised top speed of 105MPH. Driving at lower (much lower in peak traffic) speed won't do any harm.

 

[idlemarvel]

I ran my G-scale locos using a Hornby Elite 14v DCC system for years before I upgraded to Lenz and 19v, with no problems. Reduced speed is not really a problem as you would hardly ever run locos at full voltage anyway, they would be travelling too fast. The only thing I found that did not work were Massoth uncouplers which needed 19v or more to drive the servos.

 

[JimmyB]

In short no. DC motor voltage is directly related to motor speed. As an iffy analogy consider a motor car with an advertised top speed of 105MPH. Driving at lower (much lower in peak traffic) speed won't do any harm.

Unless you are travelling at 20 mph in sixth gear

 

[Greg Elmassian]

"Can an LGB motor become damaged, or lessen its operating life, by using a lower output DCC system considering the above comments on stall current and the motors are spec'd for 24 volts, for example, using the MRC dcc 10 amp prodigy elite command station which outputs 14.5 volts DCC to the track?"

Not really, you can hurt motors by abusing them, and having them draw excessive current when the voltage is low is really the same as less current at a higher voltage.

Basically the wattage consumed by the motor and the load on it will generate heat... too much heat will melt stuff... until that happens (melting) or perhaps burning brushes from accelerated wear by high current operation, nothing can really damage the motor.

Overheating is the criminal, and you can overheat a motor at virtually any voltage.

So, a lower DCC voltage will normally exhibit itself in slow top speeds. This particular unit is 10 amps, so current will rarely be a problem.

The speed of a motor is governed (as long as adequate current is available) by the voltage... the track cleaning loco and aristo 3 axle diesels need higher voltage, just the way the motors were made.

Greg