Large Scale Central

Installing battery R/C into the USAT GP-9

USA Train locos are arguably the easiest in which to install battery R/C. They are well made and have plenty of room up inside the hood for an effective antenna. I usually achieve at least 200’. Here is how I have gone about installing my RCS battery R/C inside a GP-9. The techniques are straightforward and can be adapted to other brands of R/C as well. The same ideas can be applied to most USAT diesel locos, including the bigger 3 axle models. There are basically two ways of going about it depending on how you want to set up the loco. The simplest method only involves disconnecting the track pick-up wiring from the trucks and re-connecting the wires to the output of the motor Driver pcb. The result is much the same as running on track power. The lights will work exactly the same way and go out when the loco is stopped. I prefer to have the lights on constantly even when stopped. This involves a little bit more wiring and the addition of a RELAY so that the coloured marker lamps will change colour correctly with direction change. The most difficult part of the installation is dismantling the loco. You will need a very long Phillips head screwdriver that will reach down into the holes where the screws are buried. Some screws are also under the fuel tank so it needs to be removed as well. If the screwdriver is long enough you may be able to wriggle it down between the truck wheels to access the holes. If not, you may need to remove the trucks to get at the holes. Once the body is off the chassis I remove the smoke units and all attendant wiring. They draw a lot of power and will reduce run times dramatically. I leave all the lighting wiring and the switch pcb in place. The track pick-up wiring is also removed from the trucks. These are plugs with FOUR wires attached. Leave the motor wiring in place. I have always found 14.4 volts is sufficient for a realistic top speed. In my early installations I used two 1800 mah 7.2 volt Sub C Ni-Cad packs. These provided a reasonable run time but are bulky compared to AA size NiMh batteries now available. Of course you can use a greater voltage but if you run at a realistic speed you will waste the battery capacity by burning it off in the form of heat. To make room for the Sub-C packs I had to remove two stanchions.

The Sub-C packs were tied together with cable ties and then mounted in place using a clear silicone adhesive. I use Selleys Roof & Gutter Sealant.

This method allows the RCS Motor Driver pcb to be mounted on the batteries with the Dallee sound mounted on the rear lead weight. With later installations I now use custom made 14.4 packs of 2,500 mah AA size NiMh batteries.

These give adequate run times for most situations. I don’t like jamming huge batteries into the narrow bodies as it usually requires a lot of modification to make them fit. Extra long run times can be easily achieved by utilising the rear mounted external charge jack as a port for plugging in auxiliary batteries carried in a trail car. Be extra careful not to get any glue in the jack itself.

With this particular installation I mounted the RF-RX radio receiver in the nose and connected the antenna to the track. This provided reasonable range.

Nowadays I prefer to mount the RF-RX part up under the top of the body shell right behind the cab. I shorten the RCS antenna and connect an AZARR 27 Mhz antenna from E Cubed R/C and stretch it out in a straight line as high as possible. I now achieve at least 200’ range when proper motor “noise” suppression is added to the motor circuits. Sometimes more. The rear lead weight made a great heatsink for the RCS Motor Driver IC I was using up until recently.

Here is an early BIK-U installation kit mounted in the fuel tank. This enables a hidden switch that is still accessible.

A later version of the same switch kit.

I mounted the Dallee sound in the fuel tank too. Two holes had been drilled underneath to gain access to the volume controls.

For Sierra type sound I fit the BIK-U+VC which has an inbuilt volume control.

Here is how the plugs and sockets are re-arranged for the simplified installation.

For the constant lighting version this shows how to do it.

I trust the above is of help to LS’ers. Please feel free to contact me with any specific enquiries.