Battery R/C into a C21 & K27.

[TonyWalsham]

Today I finished installing RCS battery R/C and Sierra sound in both an Accucraft C21 and K27.
Here are a few pix on how it was done.
Not knowing what the actual current draw requirements were I chose to use 5 amp RCS Basic+ motor drivers.
As the owner did not want to have any holes drilled in the bodywork I opted to mount the charge jack and ON-OFF switch behind the tender front coal access plate on both locos. This simply lifts up with your fingers.

The pcb in front with the two big coils is the unit I supply for heavy duty trail car installs. It usually fits behind a box car door so it was perfect fot use here.

The C21 has well thought out wiring that does not require any modification in the loco. The K27 is a different story. More later.
The C21 normally has a distribution pcb behind the sliding front plate which was in the way and not required so I removed it. The BASIC-5+ Motor Driver and the BIK-TC5a were both mounted with silicone adhesive on an L bracket I made up in styrene.
This assembly was also glued in place with silicone. Another sheet of styrene was glued to the speaker and back of L assembly as the support for the Sierra sound and RCS sound trigger components.
On the C21 I used two 8 cell (9.6 volt) 2,500 mah AA NiMh packs wired in series to give 19.2 volts nominal. 22.5 volts when fully charged. These were also mounted with silicone on each side of the tender.

This close up might give a better view of the parts.

For both locos I made up reed switch chuff timers from readily available alarm system parts and used two very small rare earth magnets super glued to the non metallic wheels. This gives almost exactly 4 chuffs per driver wheel revolution. I removed most of the slop in the axles with fibre washers on the axle ends.

I was not sure what to do about the antenna so I chose to mount an AZARR on top of the coal load and feed it down to the RCS RF-RX which I mounted under the metal tray. If this works OK the antenna, although virtually invisible, can be covered with some more coal

If range proves to be a problem I may re-route the antenna down to the insulated wheel pick ups on one side of the tender. This works well in some locos but because the case of the motor in the loco is mechanically connected to the body and therefore one side of the track it may not be successful as the motor will radiate some RFI. Time will tell.
As previously mentioned the C21 wiring was OK as is. All I had to do was provide a regulated 6 volt supply for the loco lights. I did try 1.5 volts as the loco has 1.5 volt micro bulbs. That is so but they are wired together in series and parallel so 6 volts was it. I used the same 6 volts as I used to power the Sierra sound via terminals #2 and #4.

Here are similar pix of the K27 that show the 8 cell (9.6 volt) Sub C 3,300 mah NiMh packs and how they were mounted.


The following pic shows the type of connectors which are secured under the front edge of the tender by two brass wire loops I fabricated out of thin brass rod. To protect the cables I used some heatshrink tubing.


I had to modify the wiring on the K27 Loco. This is reasonably accessible as the wires come to what could be called a "terminal strip" under the firebox. By removing the coupler drawbar plate it is possible to gain access to the "terminal strip". Undoing the nuts holding the wires was the hardest part. I had to cut the nuts off one screw. I was shocked to discover the pick up wires were single strand black bell wire. Certainly not up to what I would call adequate standards. This is not really a problem with battery R/C as these wires are discarded anyway. The motor wires are quite substantial and were spliced into a two way in line connector assembly I use with trail car installs. These are the same type as are used by Aristocraft for trail car connectors.
I used the same type connectors, the other way around, for the contant brighteness lighting power.
I disconnected and removed the original 6 volt supply from behind the smoke box door and fed the new wiring direct to the lights.

Both locos run superbly although they were bit touchy on the speed control when the acceleration rate was set at 5 seconds. I changed that to 10 seconds on both.

Please feel free to ask any specific questions on how I went about the various procedures.