There has been a lot of discussion about the number of loco’s that can be used with various DCC systems; yet no current consumed figures. I model turn-of-the-Century ( 20 th) and really did not know more than everything seems to work OK. I tried a few combinations to see what would really happen during operations. Running loco’s all had short trains ( 3-5 cars). the 4-4-0 was on a continuous run loop with a 1 % grade. The 4-6-0 was climbing a 2 % grade, and the 0-6-0 and Shay were on level track. All were running at prototypical speeds of about 40 smph ( 15 smph for the shay and 0-6-0).
I added a ramp meter to the layout. I was somewhat concerned about amperage consumption with my six sound units running. The display is DCC voltage over amperage used. I have 8 power districts with a tail light bulb for current limits in each; all powered by the Prodigy Advance system. You can see two of the bulbs to the upper left, in the first picture.
I did several comparisons to see what was really happening:
from left to right - top row:
Layout on, no units accessed yet
Short on one power district
Old Roundhouse Shay running, one 4-4-0 running and one 4-6-0 climbing the 2% grade
Bottom row:
All six engines at idle, sound on, lights on and all bells ringing (boy what a racket)
One 4-4-0, one 4-6-0 and one 0-6-0 running
The full lineup sitting on the layout:
Two P2k 0-6-0 with sound
Two Roundhouse 4-4-0 with sound
Two Bachmann 4-6-0 with Tsunami sound
One old Roundhouse Shay (built from a kit 15 years ago)
Interesting. It would be useful for some of us who run heavier locos and trains to see the consumption when 3,4,5,…10 sound locos are pulling hard on modest grades. This would be helpful for those with 2,2.5, and 5 amp systems, which most of us have.
Thanks for taking the trouble.
-Crandell
I don’t have DCC, but I do have a power supply with both a voltmeter and ammeter built in. The current draw is much more a function of the motor design, and less of a function of the load on the motor. The weight of the locomotive factors into the total weight of the train, and not just the weight of the locomotive. The lighting load on cars is a function of lights vs. LED’s.
For instance, an Athearn GP-60 pulls around 1/2 amp on flat track pulling no other cars. You load it up with cars and 3/4 amp is typical. A Proto 2000 SD-7 pulling 12 ore cars full of ore (real stuff) at full speed pulls less than 1/4 amp. My two Athearn AC4400’s pulling a string of 12 coal cars (real loads - heavy train) up a 2.5% grade pull almost 2 amps, but backs down to 1.25 amps when going downhill (pushed). My passenger train with three Stewart F7’s and 11 lighted cars pulls almost 2.5 amps on the hills, but I know the cars pull almost 0.1 amps each. Had I put in LED’s I bet I could have go the car lighting to drop down to 0.02 amps each.
Mark in Utah
See, those sound locos don;t draw NEARLY what people think. The stall current figures posted in the MR reviews of said locos would seem to agree with the measured results seen above.
–Randy
I think the thing with sound is you have several things going on:
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The sound chips have a high inrush current as they charge the caps. Some of the electronic circuit protection systems detect that as a short and will shut it down, whereas the older units (brute force fault protection) just ride through it.
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The ongoing load of the sound systems is probably on the order of 3 watts each, which would add about 1/4 amp on average to a normal locomotive load. While this may not sound like much, it’s probably not a steady resistive load, but a pulsed load. You get a few of these puppies running at the same time and you could overload and trigger that fancy protective circuitry I mentioned above.
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A typical DC supply is only good for 14 VA, or in other words 1 amp tops, and that’s an intermittent load - not continuous. You can see how multiple locomotives could push a typical supply over the edge.
I’ve added fans on my supplies so they don’t overheat and trip out. I figure when I get DCC I’ll need at least an 8 amp system. I’ll probably build my own supply to carry that much load all the time, something that most DC supplies are not rated for.
Mark in Utah
Bump.
This was buried on page 6 - some of the “weekend” modelers may benefit from the discussion.