Decoder Amperage Ratings

Discussion in 'DCC & Electronics' started by itdincor, Jan 6, 2007.

  1. itdincor

    itdincor New Member

    I am ready to buy decoders for my locos, from However, I note that Digitrax decoders applicable have differing amperage ratings, 1 Amp and 1 1/4 Amp. As the price difference is about $15, my question is:

    would the extra quarter amp be worth the extra $15?

    It seems to me that the extra quarter amp would allow more power, and thus longer trains. As I expect my primary emphasis to be longer logging and mining trains, and as there will be somewhat steep grades, mayhap the extra quarter amp is worth the money?

    Or, maybe not! :rolleyes:
  2. cidchase

    cidchase Active Member

    If you have an ammeter, you can measure the current draw for the loco in question.
    It will pull its maximum with the drive wheels stalled.
  3. itdincor

    itdincor New Member

    Well, since my locos have yet to arrive, I went ahead and bought the higher amperage rated decoders, where applicable. I guess the added power, and extra functions will in the long run be worth it.

    Anyway, that's done, and I'm still under budget! :)
  4. caellis

    caellis Member

    The motors themselves determine what amp decoder to buy. If your loco's are new HO they probably don't pull more then 300 to 450 milliamps when running.
    However, you should purchase decoders based on the stalled amp rating of the motor.

    You would need an amp meter to determine this and do the testing on DC.

    The stalled current is determined at the point the engine wheels stop turning when full power is applied and you are either applying pressure and/or holding the loco to keep it from moving.

    Use caution when making this test as the motor should be at stall for only a brief time(couple seconds).

    A 1 amp, or greater, rated decoder is generally sufficient for most modern HO loco's.

    If the motor attains full speed under normal loaded conditions and still draws less than one amp, a higher rated decoder WILL NOT produce more power from the loco.

    The higher rated decoder will simply run cooler and probably never 'blow'. Some decoders are protected against over load.

    I hope this helps you.
  5. itdincor

    itdincor New Member

    The vendor I bought from, First Hobby, advised particular decoders based on Digitrax recommendations. I had a couple of choices, and went for the decoders with a 1/4 amp higher rating, and with more functions. As these decoders are specified by Digitrax for the particular locos, I misdoubt there will be any problems from that. I just may have spent $30-$40 more than absolutely necessary, that's all. I was getting a bit twitchy, having spent so much already. But, now I've all the basics ... I think.

    From my life asea I learned to buy the best available that could be afforded. It seems to me that I have done so, at least based on the experts' recommendations. And, if this actually ensures longer life, then it's likely money well spent.

  6. NYNH&H

    NYNH&H Member

    The more expensive decdoer probably has a lot more features and whatnot, most of which are probably not of much use for most people. Most HO locos do 150-200ma, n scale less. Unless you have a real powerhog, anything that can handle an amp is plenty. If the decoder is too small, it will eventually melt or smoke. Then it is done for. Having a more powerful decoder will not help you with longer trains.

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