Twin Motor DCC fitting

[reddragon]

I have some older Hornby diesel locos where I fitted a second motor so that they could actually pull a decent load.

 

Any advice on what decoder power limits I'd need of issues to consider before I fit a chip? They have directional lighting too.

[SRman]

It depends on the types of motors involved. There are quite a few decoders that can take up to 2 amps peak loads, and there is usually a fair amount of room inside these locos to fit physically larger decoders.

As an example, I have a twin motored Triang-Hornby Hymek, with the original heavy metal motor bogies. they are wired together and have one TCS T1 decoder hard-wired to both, with no problems to report. In fact, it runs very nicely, very smooth but a bit noisier than Heljans models. These motors are not noted for low power consumption!

I have also used TCS T1 decoders in several London Underground trains, two of which are white metal kits with five cars each, and a third train is all resin kits, also of five cars. All of these use two Black Beetle motor bogies wired together with the aforementioned TCS decoders, one decoder per pair of Black Beetles.

There are better quality decoders available than the TCS ones, although they are actually quite good anyway, but the likes of Lenz, Zimo and ESU have in-built overload protection, where TCS has their 'goof-proof' warranty (even if you blow up a decoder through your own carelessness or stupidity - the latter was one in my case on another model!).

For the lighting, LEDs use a lot less power than incandescant bulbs. Check the power output limit specifications for whatever decoders you favour.

Edited July 16, 2020 by SRman

[JimFin]

I have a couple of Bemo G6/6 locos that have twin motors had had the same conundrum. Eventually I tried one of the LAIS decoders with 2A max and 1A continuous. (860012 from CM3 Models). Felt at the price, was worth a go. Its been perfect and fitted the second loco with the same and had no problems. Used them on a few others with minimal issues. I know lots of folk seem to have issues with this brand but TBH for basic functions they seem perfectly adequate and my experience - so far - less failures with these than Zimo and Gaugemaster.

[34theletterbetweenB&D]

On ‎16‎/‎07‎/‎2020 at 13:31, reddragon said:

I have some older Hornby diesel locos where I fitted a second motor so that they could actually pull a decent load.

 

Any advice on what decoder power limits I'd need of issues to consider before I fit a chip? They have directional lighting too.

If the two motor units are well matched on DC, a single decoder can do the job. Just measure the stall current at 12V DC (which will include the lights) and use a decoder with a larger continuous output rating  (to be safe I would want the rating 50% greater than the 12V stall measurement).

 

If the motor units are not well matched, or on DCC installation it is very obvious that one starts well before the other, and/or they don't match well through the speed range; then separate decoders per motor and matching the performance by CV adjustment is the way to go. (If that were the case, I'd go for a centre motor replacement at that point.)

[Mike Buckner]

When using a single decoder for 2 motors, do people favour wiring the 2 motors in series or in parallel?

[Gavin Liddiard]

On BMRGs "Mostyn" we have a fleet of twin motored Hornby based Class 25s (3 pole pancake), a Hornby based twin 5 pole Class 24 and some Lima based twin pancake Class 40s.

They are all wired in parallel to either Lenz or Zimo decoders. They don't draw a lot of current so just the standard decoders at the time were sufficient.

To match the motor bogies we temporarily rigged them to run alone and ran them all on a circuit of track for some time to see which made the best pairs.

For the Hornby type 2 we wrote an article when we fitted twin 5 pole motor boies to our 24047. In it we discussed the fitting of the bogies, wiring for DCC and also fitting all wheel pick-ups which is a must for reliable running. The article is now on our website in PDF format and can be found here: http://www.barrowmoremrg.co.uk/mostyn_projects/MorePowerForYour24v2.pdf

Edited July 19, 2020 by Gavin Liddiard

[SRman]

9 hours ago, Mike Buckner said:

When using a single decoder for 2 motors, do people favour wiring the 2 motors in series or in parallel?

 

Parallel.

[JST]

On 20/07/2020 at 01:43, SRman said:

 

Parallel.

 

Fair comment but what about using 6v CD motors in series - a possibility?

[SRman]

9 hours ago, JST said:

 

Fair comment but what about using 6v CD motors in series - a possibility?

 

The assumption is that we are talking 12V motors. If you use motors with lower voltage ratings then yes they will need other variations on the wiring. That might include wiring in series, limiting the top voltage supplied by the decoder, or adding resistors, or combinations of those things.