55 ton 3 truck shay sound card

[Chuck N]

When you mentioned you had a 12v limit, I wondered how my shay performed at various voltages.  I have a 2-truck Bachmann Shay.  This afternoon I took a volt meter out and tried to measure the speed at or near the voltages mentioned.  My mainline is a little under 90' in length.  The engine with no cars started moving at between 3 and 4 volts.  At 12.3v it took 110 seconds to do a lap.  This scales out at 11 mph.  This is a very prototypical speed for a Shay.  In my mind it was very slow for a garden railroad.  I do not like running things very fast, but this was visually slow for me.  At 14.1v it took 84 seconds(14mph) and at 18.7v it took 57 seconds (22 mph).

Pulling a train with 6 Bachmann 2-bay hopper cars and an Accucraft short caboose I got the following values:  13.9v 105 seconds (12 mph), 12.1v 133 seconds (9 mph).

If you have a chance try to find a layout in your area and take your engine and run it at various voltages.  See if you will be happy with the speed, or lack of it, at 12v, before you spend the time and effort installing the controller.

Just a suggestion.

Chuck

[gprice]

Kevin is absolutely correct, if your receiver requires more than 11.1 volts to operate properly, then I would go for my first recommendation which was the 14.8 volt battery.  I presume your transmitter is powered by its own separate power source.  You will have to check the specs on your receiver to determine what the high and low voltage limits are and get or make a suitable battery pack.

Have fun!

Bill

My receiver runs on a constant 5V provided by an Electronic Speed Controller (ESC) which has an inbuilt battery eliminator circuit, it is the ESC that has a 12V limit on it but it is capable of handling up to 20 Amps.
The transmitter has 8 AA rechargeables so that is not an issue.
I have spoken to another modeler who has  Garret articulated loco with 2 motors, he is using an 11.V Lipo battery (12V when fully charged) and it runs fine .

Chuck N has experimented with speed at different voltages and 11mph sounds good to me as I run all my trains real slow, I am guessing that the voltages he measured were variable DC but the ESC I use applies a constant voltage to the motor and switches it on and off at a high speed, the motor speed is determined by the on time/off time ratio.
Effectively it is Pulse Width Modulation.

My other locos all run on 9x1.2V (10.8V) 2700mAH NiMH AA batteries and I have plenty of throttle movement range but they only have 1 motor.
I was just concerned that because the shay has 3 motors it would need a larger capacity battery.

Thanks for all the advice I now have a fairly good idea about how I will go, both with battery size and sound options