In planning my layout I believed I was going to need more than just one 5 amp booster. So, I hooked up a Tony’s RampMeter in-line with the booster and the main bus to measure volts/current.
Test setup:
Mainline is about 45 ft. Main bus is 12 gauge solid with about six 20 gauge feeder drops spread around the 45 ft so far. I have all of the track laid as in the Plan below in my sig with the exception of the Taylor yard and the TT/yard. I kept the 5 trains running around the outer mainline as I was solo. I currently have no breaker districts. It is all one big bus. The two reversing sections are not connected. All five locos below were sitting on the track at test startup.
Power applied - RampMeter read 0.08 amps
Stewart S12 no/SND running - 0.12 amps
BLI 2-8-2 #1 w/SND on - 0.13 amps, then running - 0.19 amps
BLI 2-8-2 #2 w/SND on - 0.22 amps, then running - 0.29 amps
P2K switcher w/SND on - 0.35 amps, then running - 0.43 amps
Athearn F3 no/SND on 0.45 amps, then running - 0.47 amps
All stopped idling - 0.22 amps
So, with 75% plus of my track laid, 5 loco’s running (3 with sound) the maximum current draw was 0.47 amps. I’ve heard that one would be amazed at how little current is actually drawn but I must say I was surprised at these results [:)]
This morning I applied power again with the loco’s left in the same state from the evening before and the current was again 0.08 amps
It sounds to me that you don’t need any boosters. Any of your DCC starter system will handle what you have described. It’s not the size of the layout so much as it is the number of locos. Like I’ve said before, on our club president’s 20 x 25 layout we ran 10 trains, 3 with sound, on a Zephyr.
When DCC was first being developed and the early decoders cost nearly $100 each, manufacturers devised their “stall current” measure of power consumption as a way to protect themselves from complaints about burned out decoders and demands for replacements.
Decoder technology has improved drastically over the years, and so have the motors in our toys. A 5 Amp system should be more than adequate for an average home layout because you probably won’t have room for enough engines running simultaneously to reach that level of power consumption. The amount of track involved is immaterial unless you have power-consuming lighted passenger cars or some such sitting on all of your sidings.
It would be interesting, though, to see what the ramp meter shows as you make all those locos begin to pull reasonable loads behind them. I think you may find that your amperage draw creeps up into the 1.5 - 2 amp range with 10-20 cars behind each engine, somewhat more if they are towing up grades. This is a SWAG, so maybe you can test it yourself and tell us what you find? You won’t be able to run 5 engines simultaneously, but you can test each one with the same load and then add their derived values for a total.
I do agree with the others, and feel that you appear to have lots of reserve on your layout. I have the 5 amp SEB, and I don’t think I have come up over the 20% mark in draw at any one time since I rarely have more than two locomotives working at once.
The other thing is that the guidlines have suggest enough booster to accomodate all of your locos stalled. While that is the foolproof, must be enough, solution, it is probably also a bit of overkill. Your experiments, and the ones Selector brought up, will probably let you get a more realistic idea of what you need. Add some cushion on top of that, and you’re set.
I had 22 cars behind those 5 locos total, so, average 4 cars behind each loco. I have a very short 2% grade and 3 of the four curves around the outside mainline that these were running on are elevated.
There are probably some start up spikes and as the the other posters have mentioned the dreaded stall current. But those are all special conditions. So for practical purposes I don’t think you are missing anything. The primary booster should be plenty. Like many Model Railroader things, DCC is one area that is often WAY over engineered. Our club took into account the newer higher efficiency locos and downsized when we converted from Railcommand to DCC. We had 13 x 5A. power districts and went to 8 x 5A. which is still probably way more then we will ever need. Of course, power consumption isn’t the only issue, we like the isolation of wiring and short circuits to one part of the layout (yes, we know there are other ways to do this).
It’s not how many engines you have but how many you will be running at the same time. Multiply the number of throttles (assuming one locomotive per throttle) you have by the average stall current of your engines and you will have the number of amps necessary for your layout. I have a large HO layout with 10 throttles and use two 5 amp power supplies, one for the command station and one for the booster. If you are running a lot of lighted passenger trains, you will have to increase your amperage.
That’s what I would say is overkill (though not necesarily a bad thing). You’re not likely to have one loco drawing its stall current, let alone all of them at once. BUt, it is true that if you design it that way you are set, for sure. I expect that half would do it, but I don’t have the numbers to back that up.
Alan_B, I just read the other post back from Jan 07; appears to be consistent results.
My expectation is that I will not have more than 4 or 5 operators running 4 or 5 trains at one time with some number of loco’s (5 or 6 more ?) sitting idle in yards and or TT.
So, my conclusion is that I am happy I invested in the RampMeter. My original power consumption calculations showed I would need 2 boosters in addition to the 5 amp command station I have. So, the investment saved me ~ $300 and I now have a “real” indicator should I ever need to add more power.
Last, sometime back I had also divided the power source(s) up into breaker districts as it is more likely that there will be a derailment somewhere, sometime.
Question here will be do I invest in the commercial electronic short protection devices or the simple light bulb - another thought for another thread [;)]
With 48 feet of mainline track, the only time you need to worry about it all is if you are operating with 4-5 guys. Even then, you’ll know within seconds who the culprit is. However, if you want the other 4 guys not to razz the short-maker, either method seems to be effective–one being almost negligible in cost.
As far as I know of, circuit rbeakers used to seperate the layout into power districts are only available in power boosters. I’m expecting my layout to be divided into at least 9 seperate power districts (in such a small space, too!) to make sure that if a short occurs somewhere there’s always something else to do. If I have 9 power boosters on my layout, that’d be fantastic, except that I don’t think I’ll ever have more than three trains running simultaneously. In fact, I’d say the maximum that can be running is no more than 6 trains, and I doubt I’ll ever have that many people in the room.
Do circuit breakers come seperately now, or are they still combined with power boosters?
No, you aren’t missing anything. FOr several reasons.
The quality of motors has improved. Even STALLED most modern HO models draw less than .5 amp. Check the stats in MR and other reviews.
DCC systems, when they say 5 amps, usually MEAN 5 amps. Most DC power packs on the other hand, usually give a total power output rating which is more loke the sum of what you can draw ont he controlled DC output AND the AC accessory output. Not all that is available for the trains, so peopel get DC packs rated at 25VA and think they have 2 amps and can;t even run 2 Athearn Blue Box locos, so when they switch to DCC and want to run 8 locos at once they think they need three 5 amp boosters.
It’s easy enough to add if you find you are lacking power. No need to spend big up front. And the key factor is how many locos you plan to run. A 50x100 layout with 4 locos running needs less power than a 10x20 with 10 locos running. One caveat, in a really large layout you might want extra boosters just to keep the bus runs short. An example would be my basement, the long wall is over 50’ long, just not very wide. Instead of tryign to run over 50’ of bus wire, I would rather put a second booster partway down the long wall and keep the runs shorter. Even #12 wire, over more than 100 feet (remember complete circuit! if the furthest point is 50 feet away, that’s 100 feet of wire the electricty has to travel through), will have a noticeable voltage drop. Locating two boosters in the space about 15 feet from the ends covers the entire space with a maximum wire run of 30 feet - 15 feet out and back: -----B------------B----- like that.
Tom, I am also rethinking the need for a booster or a better DCC system. I have a mer Easy Command with only 1 amp! I have ran 4 BLI’s with QSI sound and a DC Bachmann at the same time with no problems? I was told 2 engines would be the max I could run. 1 BLI had a 20 car drag, nother one 15 cars, next one 8 cars and the rest where with out a drag. Reason the other ones where not hauling freight, I was out of room all most. B line is only around 100 feet.
Breakers come in single, dual and quad form. Even though you might have 9 districts, you can start out by wiring them all to the same booster. Then as you need more power split them out to another booster. It is easier to do that up front than try to do it later. I run 10 different districts on my layout.
While my experiment may indicate no additional boosters needed for current, I will use the RampMeter and go spot check voltage at various distances around my layout from the command station.