Leaving Digital engines on track idling

[Nathan]

Bob,

I will see what I can do with the the equipment I can get my hands on.  Although there are a number of DCC Sound Locomotives in our club, at this time I only have one, so I will need to borrow the others, as we do not have a train show for several months and that is when we have them all in one place at one time.   Also, all our locomotives are Large Scale.

I will check with the HO scale club at TTM where our large scale club is located and see if they have any measurments avaliable.

At the last train show I did notice the following which will give some idea of what you can expect:

NCE Power Pro 10 amp system with one booster for each loop.  An RRamp on the ourput of each booster.

Loop 1:  Bachmann 55 ton Shay with factory sound, Bachmann Big Hauler Porter with non sound NCE DS-408, Aristo RDC with QSI sound that was turned off at power down.  The idle current was around 0.1 amp.  If you turn on the QSI sound it went up to about 0.2 amps.  With the 3 of them running at about the mid speed range, lights on and both sound units operating the current draw was about 2 amps.

Loop2:  Two Aristo Diesels, both QSI sound decoders.  I do not remember the idle current with both sound units off.  Running the one unit and the other idle on the siding with sound on, and both units with lights on was between 2.5 and three amps at about mid speed.  Both units running mid speed ran between 4 and 5 amps.

One note, you asked about the idle current in non addressed verses addressed mode at zero speed.  There is no differance if a decoder is addressed or not.  It is 'reading' the data being sent out and 'looking' for its address.  The only change will be if you change something like turn on the head light.

I will have to remember to make sure that all the lights and other itmes are turned off when I start the measurments.  Some locomotives have some itmes that are not controled by the decoder but are 'on' all the time.  I will try and let you know if I find any of these.

[Yampa Bob]

I didn't think there would be any difference in non-address or address modes, glad you confirmed that.

Please don't go to a whole lot of trouble with this. Members often ask "How many sound locos can I run at the same time with EZ Command".  My honest answer is "I don't know, try several and see". Some have reported only being able to run two, I think three but at reduced speeds.

As an experiment, I recently put 8 DCC non-sound locos on the main, (not in consist) , and got them all moving, quite a trick on my small layout. The breaker never tripped, but the locos all ran very slow.  In theory, and according to Kirchhoff's law, one could run 20 locos at full throttle, but they just wouldn't move at all.

My point being, if I can run 3 or 4 DCC locos and maintain realistic speeds, say 35 to 45 mph, I certainly wouldn't consider a booster.

[Nathan]

Bob,

Just did a quick and dirty test with a small loop of track.  Using my NCE system and the RRAmpIV large scale meter.  It only reads to 0.1 amp.

Test unit #1: an NCE decoder tester with an NCE DS-408
Test unit #2: an NCE decoder tester with an NCE D-808

With both units hooked to the loop, four functions on, and both speeds set to max 0.1 amp.

added Test uint #3: Bachmann Big Hauler Porter with NCE DS-408.  No change with headlight on.  At max speed, no cars attached 0.6 amp.

added Test uint #4: Bachmann Large Scale 55 ton Shay with factory sound and fire box flicker.  With headlight on and base sound working 0.2 amp.  At max speed, no cars attached 1.0 amp.

Coupled the two locos back to back, wit the Porter at speed 0 and the Shay pulling it at max speed 1.4 to 1.5 amp.

With the Shay still pulling the Porter set the Porter to max speed trying to go the other way 2.3 to 2.4 amps.

Turning on the bell and whistle at most saw a 0.1 amp differance.  I know the QSI and Pheonix units draw more idle current.

[Yampa Bob]

I recently did a current test on a DC powered track, with 4 Bachmann GP40 DCC equipped.  I started with one loco pulling 10 cars, then added locos in consist.

Power was a Spectrum Magnum, rated output .7 ampere.

With one loco, current draw was .29 amp, top speed perceived as normal
With two locos, current draw was .42 amp, no perceived reduction in speed
With three locos, current draw was .56 amp, perceived about 3/4 speed
With four locos, current draw was .70 amp, perceived about 1/2 to 3/4 speed

Yeah I know, got too much free time on my hands. I mostly do it to dispel complaints (rumors) of a certain locomotive only being able to pull 3 or 4 cars, or only being able to run 2 non-sound locomotives on EZ Command.

I tune all my cars for .08 to .1 ounce required pulling force, even my little GE 44 ton can pull 10 cars with no problem.

Apparently the DCC decoders are very efficient. My main interest now is current draw of one HO sound equipped loco on DCC power, pulling about 10-15 cars at full throttle.

[grumpy]

Bob
I have 2 Athern F7s with DCC and sound if I run both of then of them in consist  They will kick out the breakers . If I run 1 with sound and 1 without sound  it is okay. That is the max that I was able to run with the 1 amp power supply. The sound decoder draws al ot of amps.
Don

[Yampa Bob]

Apparently so, it sorta confirms my WAG of .6 to .7 amp for a single sound decoder.