not enough power?

Discussion in 'FAQs' started by eve_9d9, Nov 2, 2007.

  1. eve_9d9

    eve_9d9 Member

    heres something I didnt think of.......when I built my layout I just added the section of the track with the power plug on it, and planned to just use the cheapo power supply that came with the original bachmann set I purchased......for the time being at least, but now the layout is pretty huge, and that little power supply doesnt seem to have enough power to run the train properly, could this actually be the case? could the amount of track Im using be too much for the supply? I only have power going to one section of I maybe need a bigger supply now? and more connections throughout my layout? sigh...Im kicking myself for not thinking of this before........if this is the case, any ideas how I can fix it without having to tear up part of my layout? thanks
  2. Herc Driver

    Herc Driver Active Member

    I'm not the world's foremost expert on power packs, but to clarify your the train slowing down the further away from the power pack it travels? Do you need to increase the amount of power required to maintain a constant speed all the way around the layout during the engine's journey?

    From my experience, the power pack supplied by Bachmann isn't the best and has just enough power to run a small layout, maybe a very small layout at that. I know from experience on my layout - which isn't very big. (I bought a Spectrum power pack and it would often overtemp trying to meet the demand of running a two engine lash up all around the layout.) So, you can certainly test the track for voltage drop around various sections of rails with a cheap light bulb tester - or get high tech and use a multimeter. Check all your connections, make sure all the track is connected properly with no mis-aligned track connectors. (If there's a gap in the rails, although not technically desired, the connector should carry the current to complete the circuit.)

    If you find that there's a voltage drop, there are several choices to could block the track (running more power leads to different "blocks" of rail which are insulated from each other so you're not parallelling current, you could try buying a larger and more powerful power pack. (And I'm hoping someone with waaaaay more electrical knowledge will step in here and add to this thread and my overly simplistic ideas.)

    Lastly, is the track clean? Make sure the engine's wheels are clean (what manufacturer is your engine?), and the track is clean so that you know you're getting a proper and effective electrical connection between the two.
  3. who_dat73

    who_dat73 Member

    Just my thoughts

    First look into buying a better power supply as the Bachman boxes arnt made to do more then a short loop of track, if that isnt in the money right at the moment did you solder your rail joiners? If so you can solder more wires to the outside of the rails to make sure you have power running to the farmost points of track. Soldering track also helps get the power to move between joints.

    Just a side note and this may sound like a duhh point but I was young and dumb when I started all this :thumb:

    When I first tried to solder my track the first time I just grabbed the solder I used to work on the copper pipes and made a real mess of my track. Go to Radio Shack or the equal to it and get real small thin solder and put a small amount of flux outside the rails at the joiners to help it run in or you will melt the ties tring to heat it enuf to get it to flow into the joiners..
    Hope this info helps and I am sure you will get more good tips from all the others.
  4. ezdays

    ezdays Out AZ way

    There's no doubt that your problem is from lack of power. To start with, that Bachmann power pack provides a minimal amount of power. If you look at the writing on it, you will see that the power output is somewhere between 4 and 7 VA. That means that it will only put out about 1/4 to 1/2 amp on a good day. The higher the load, the lower your voltage will be and you could overload the pack.

    You also need consistent voltage around your track. You can achieve this by running heavy-gage feeder wires under the tracks and tap off every so often to attach them to the tracks. Every foot or so would be good. The same goes for turnouts, or anywhere you have an insulated rail joiner. Rather than use this approach, I'm also running DC, but I take each tap back to a central point and join them there, then if I continue with DC, I will build a switch panel or I could convert to DCC easier.

    Depending on how many engines you are running, and how many accessories you have, you really should get a power pack with a higher VA rating. I would recommend the MRC Tech4 series which has lots of other features besides a higher output rating. It has programmable functions including braking, momentum and voltage limiting.
  5. Herc Driver

    Herc Driver Active Member

    I second Don EZDay's recommendation on the MRC Tech4 series. I bought one to replace my Bachmann Spectrum and have been very happy with it. Granted my layout is not large by any means (door sized Nscale) but the Tech4 can easily power as many engines as I have room to run with no power loss. I have the Model 260 with a total output of 20VA. The Spectrum power pack's output was 10VA and just couldn't handle the demands of running more than two diesels without overheating problems. I'm sure there are other power packs to choose from as well. If you have a local hobby store, and get a knowledgable salesperson, you could buy or order a power pack that fits your needs - and enough power to accomodate what your layout might grow in to in the future.
  6. PWRR-2207

    PWRR-2207 Rogue Islander

    and add feeders...

    like they said above because the resistance in the metal rails (even clean ones) is greater than copper wire. Yes, you can add a larger potential energy source (power supply) but you cannot escape Ohms Law wherein all that extra energy comes out as heat :curse:
  7. chessie4155

    chessie4155 Active Member

    Get the better MRC power pak and add feeder wires to more section of track. Use the cheapy Bachmann, Tyco, LifeLike, etc. paks to power your street lights , lighting for your houses or other things, just my 2 cents worth..
  8. 60103

    60103 Pooh Bah

    eve_9d9: if the power pack runs the train nicely where the terminal section is, but not at the far end, then your problem is voltage drop a.k.a. extra resistance, caused by the rail joiners (mainly) plus the extra rail.
    First solution is to run an extra pair of wires of reasonable size (16 gauge or bigger) to the far end. You may want to put in another terminal section or solder the wires to the rails. Use a short piece of small wire to go to the rails, then add it to the bigger wire. If that cures the far end problem, you could add a few more. You should also check the rail joiners to make sure they're tight and in place.
  9. eve_9d9

    eve_9d9 Member

    Im going to run a few feeder lines from the far end of the layout, where the ballasting isnt done yet and I can still get to the bottom of the track easily.....using the smaller pak to power lights is a great idea! Im so mad I didnt think of this soonerbut what can you and learn.....thanks for all the help everyone, Ill have a new pack on my christmas list.
  10. scubadude

    scubadude Member

    Make sure that flux is Gern Industries Industrial Flux. I understand it will improve conductivity by 5% sign1sign1sign1
  11. Gary S.

    Gary S. Senior Member

    My two cents:

    First, we are talking about a single locomotive here.

    If the power pack is "powerful enough" to run the loco while it is on track near the wiring terminals, then it is powerful enough to run the loco further away too.

    If the power pack is "powerful enough" to run the loco on a small loop, then it is powerful enough to run the loco on a large multi-looped spaghetti bowl.

    As 60103 mentions, the problem is the voltage drop which occurs as you get further away from the power pack. And if you have poor connections in the track, this voltage drop is going to occur whether you are using a $10 train set pack or a $200 fancy pack.

    So, a high dollar "more powerful" pack is not a cure for poor connections which place high resistance in series with the locomotive. It is all Ohm's Law.

    Certainly, a pack with more watts is necessary for running multiple locos. But we are only talking about a single loco.

    Here is some math for anyone who is interested:

    $10 cheapie pack vs $200 good pack

    We have set the throttle at a position where each pack is producing 12 volts. Somewhat arbitrarily chosen, our locomotive motor has 35 ohms of resistance and it is sitting on track close to the pack, and the overall track connection resistance = 1 ohm.

    In both cases, current = voltage divided by ohms. To calculate the ohms, we must add the track ohms to the loco ohms because this is a series circuit. The ohms = 35 for loco + 1 ohm for track = 36 total. So the current to the circuit is 12 volts divided by 36 ohms equals 1/3 amp. The actual voltage seen at the loco = current x ohms of the loco = 1/3 amp x 35 ohms = 11.67 volts. We lost 1/3 of a volt in the track. Not too bad, and the loco runs near full speed.

    Now same deal, packs putting out 12 volts, but the loco is way over on the other side of the spaghetti bowl, and the track connection resistance is 25 ohms because of poor rail connections. So, current = 12 volts divided by resistance, resistance = 25 ohms in track + 35 ohms of loco = 60 ohms. Current = 12 divided by 60 = 1/5 amp flowing in circuit. Actual voltage at loco equals current x ohms of loco = 1/5 amp x 35 ohms = 7 volts. So, the loco on the other side of the track is only seeing 7 volts. We are losing 5 volts in the poor connections and the will run at barely over half speed versus when it is close to the power pack connections.

    Notice all this has nothing to do with "power" which is watts, which is voltage x current. It all has to do with the voltage and the resistance of the path.

    Now, I'll grant you that the nice power pack will give much better throttle response, and all kinds of other pluses, and may actually give out a purer DC versus the cheapie power pack, and this may help the above problem a little bit, but an expensive pack is in no way a fix for poor track connections.

    Run as many feeder wires as you possibly can, to all portions of the track.

    Oh... I have been in model trains for barely over 2 years, but am an electrician. If there is something I am missing here, please let me know!
  12. doctorwayne

    doctorwayne Active Member

    Pssst! Gary! You missed a chance to shill for GERN Brand Flux!! :p;):-D:-D:-D

  13. ezdays

    ezdays Out AZ way

    Gary, you did a fine job of analyzing the problem and your conclusions are right on, you cannot fix a track problem with a high-end power pack. There is one saving grace there though, a high-end supply, like the Tech4 is not likely to fold over because of load. It's all about the voltage until you start loading the supply, then the current plays a large part. Cheapo power packs are not regulated, and so the higher the load the less voltage it delivers, and the higher the AC ripple. The results are the same, poor running locos. For that alone, I would not recommend using one of those $10 power packs, you're spending good money for your locos, spend a bit more up front to run them.... and yes, make sure your trackwork is electrically sound.

    BTW, talking about solder, you can use a rosin-core solder, but I always use a liquid flux as well. I paint the joint and the ends of the wires, and "tin" the wires before I make the connection. The results are a good-looking and secure solder connection.
  14. Gary S.

    Gary S. Senior Member

    Missed it big time! I was doing some research, and it came to my attention that every transformer uses flux. Very interesting. I started digging even deeper, and I cannot find a single transformer manufacturer that uses GERN brand flux in their transformers. What is up with that? Seems we are missing out on potentially enormous profits here. Surely GERN brand flux is 3% more efficient than whatever kind of flux they are using now?
  15. Gary S.

    Gary S. Senior Member

    Thanks Don. The cheap power packs probably have a fairly high internal resistance, and that has to be calculated into the equation too. The result is, as you mention, that as the current goes up, the internal voltage drop goes up, leaving less for the loco. All this would be a function of the load connected to the pack, and would come into play whether the loco was 4 feet away or 100 feet away. If the cheap power pack will run the train at 4 feet away, it would run it just fine at 100 feet away if we used big bus wire and good connections to keep the resistance down. Resistance in series doesn't cause an increase in current load, it actually causes a decrease in current load.
  16. eve_9d9

    eve_9d9 Member

    I cant beleive I didnt think of this..............Im installing a buss line and feeders this weekend, and Ill put a new power pack on the christmas list....hopefully I can do this without tearing up my already ballasted sections too badly, thanks for the info guys, Ill post some pics when I get it wired......
  17. PWRR-2207

    PWRR-2207 Rogue Islander

    Oh! Try putting a piece of that blue paint masking tape over the spot you are going to drill. It should not grab too many ballast bb's and it will keep the drill from making a spinning mess...

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