What risks do I run shooting my layout (N scale) with 13 volts (measured with a RRampmeter, so a DCC reading) vs 11 volts? I am asking because on the club layout, with the little DB150 switches set to N and both boosters running four power districts each through PM42s I am getting pretty much 11.2-11.4 volts at the track no matter where I check. We've been having some performance issues at that voltage, or at least I THINK it's because of that voltage. Large sound locomotives stall a lot and crawl at ridiculously low speeds around the layout, even if I fiddle with the CVs to turn off BEMF and boost the voltage to the motor as much as I can. A clubmate and I tonight, risking only our own locomotives, switched the boosters to the "HO" setting, which gives us around 13.1-13.2 volts to the track, also measured on a RRampmeter, and the problems of really slow and spotty performance amongst the sound locomotives went away. My Zephyr at home delivers about 14 volts to the track. I don't want to "fry" anything.
I run my track voltage around 13.2 volts (measured with an RRamp meter). It doesn't hurt anything. One thing to remember is there is a voltage drop between the input and the output of the locomotive decoders. So if you have 11 volts on the rails and there is a volt and a half drop between the decoder's input and output the locomotives motor is only getting 9.5 volts.
The manual of the Intellibox states that with the N Scale setting, it will deliver 18V to the track as a maximum. Measured with a conventional AC meter, I get around 16V on the track, so the real voltage is somewhere between 14 and 15 V. I have no power-off switches, so every decoder gets power permanently during our sessions which last 5-6 hours. Never had any troubles or fried decoders. hth Michael
There are N scale as well as Z scale decoders that are recommended for HO locomotives because of their physical size. Nothing I have read says that you have to operate them at the lower scale voltages. I operate my N scale home layout with the DB150 set for HO and I do get better response from the higher voltage. We do the same on my clubs N scale layout and we have never had a burnout. The only thing is if you run across someone who will not use the higher voltage you will have to accomodate him.
The increased voltage will shorten the life of the n scale motors as they were not designed for long term running at anything above 12 volts. Sound decoders really draw down on the available power and running multiple units at the same time can and usually will have negative and sometimes unexpected performance effects. (switch set at N, 11.2 v) Setting the Super Chief at HO is 13.2-13.5 v. The decoders are not the issue; they can take varying voltages - small N scale motors were not intended to run at 13.7 v at an extended length of time. As always, your railroad rules supercede all others
If you run your trains tearassing around your layout constantly the motor may be getting enough current to warm it some and they should be allowed to cool down. But if you operate at scale speeds the voltage and current levels will not damage the motor. If you hook up a rramp meter in series with the DCC buss to read the current you may find the current being drawn may be lower operating at the HO voltage than when you operate at the N scale setting.
I will try that. That's a good point. Our locomotives tend to run scale speed. We get on people for running things at ridiculous speeds. With modules of known length and a handy scale speed chart on the wall everyone can figure their speed even if they cannot see it.
I don't know about the Zephyr but the DCS100 has a trimmer pot to adjust track voltage without having to go to HO setting to get a higher track voltage. In the manual section 7.8.1 adjusting track voltages describes how to do
I just looked up the manual, and on p. 37 of the current Super Empire Builder manual it tells how to do it. Thanks for the suggestion!
There are several risks taken when running at an over scale voltage. N Scale motors and their accompanied accessories are designed for 12 volts. The maximum output of a decoder to both the motor and the accessory functions is a factor of the input voltage. An NMRA compliant decoder can take 22 volts coming in so it won't be damaged. There are a few sound decoders that should not see more then 16 volts so even on the HO setting, they will not burn. However, those 12 volt motors will get damaged with constant over voltage. An even bigger risk is to the lights, especially older lighting with bulbs. The extra heat alone will melt plastic shells. After the plastic deforms on a $100 engine, the bulb should at least burn out from the overvoltage to finish the damage. Think also about lighted passenger cars, marker lights, etc. KATO has had a warning on their products and web site for years concerning this. Their were many reports of damaged passenger car roofs before they redesigned their lighting with leds. There are still a ton of cars with the older bulbs in them. So run over voltage if you want at your own risk. The approx 14 volts from a Zephyr should be OK because there is some drop through the decoder components. Its output can be dropped closer to 12 volts using a pair of bridge rectifiers on the track outputs. A clubmember had to modify his own Zephyr because his speeed tables set at home with a Zephyr would be all over the place when he ran on our club's boosters set to N Scale. On the N scale setting, 11.8 volts from the larger Digitrax boosters under load is about right. I've monitored several including my own and that's what the RRampmeter and a DVM read. Martin Myers
Both of you are talking as if the track voltage setting is what is delivered to the motor. For all practical purposes this is not true. Unless you run your engines at max speed all of the time, the life of the motor will not be meaningfully reduced. The simple solution is to never run your locos over about 80%. For extra safety, you can program your decoders so that the max speed voltage is less than 80% of the max. This, OTOH, is a real concern, as most N scale decoders do not have much if anything in the way of features for adjusting voltage to bulbs or LEDs. Solutions could include installing new, higher value resistors on function circuits or passenger lighting kits, but of course that is a lot of work and not easy to reverse if you change your mind again.
You are right this should normally not be an issue. Most of the DCC systems on the market run at more then 12 volts. Most run at less than full throttle. My concern was that the OP was concerned about top speed and liked the speed when running on 13 volts. That leads me to believe that he runs all out frequently and may actually do some damage to his motors. Martin Myers
We don't run all out. I pretty much never do. I am taking this caution, however. I may take a shell of a loco at the next opportunity and see how much voltage the decoder feeds the lights and the motor at different throttle settings.
