Connect the decoder in parallel, but try to measure the current draw of both motors combined under a heavy load to determine how hefty a decoder you're going to need. If there's room, you may need an O scale decoder to handle the current load.
I installed a single TCS T-1 decoder into an Athearn dual-motor DD40X locomotive and it handles the load okay, but I haven't pulled a really long train with it up a 2 percent grade, either.
In the early days of DCC, decoder manufacturers came up with the "stall current" measure to protect themselves against warranty replacement demands, but most locomotives will spin their wheels instead of stalling under load.
Thanks for the help guys.
I know very little about decoders and only installed one in a GG1.
The T1 has never been run like all the rest of my Bowser engines so I don't want to replace all their motors if possible. What is the best way to determine what size decoder I will need to run the two motors?
Doc
To verify the current at STALL, you will have to setup a DC ammeter. If you have a V-O-M (Volt-Ohm-Meter; also referred to as a multimeter) set it up to measure current. Make sure it can measure current over 3 amperes. Place it in line with your power pack's output to the track by removing one wire from the output terminal and attaching your meter to the open terminal and the wire you disconnected. This places the meter in SERIES with the connection to the track. Gator clip jumper leads will make this type of connection simple. Set the throttle to 12 - 14V with the loco on the track and with your hand stop the wheels from turning, creating the stall. Measure the current. This value will determine your decoder requirements.
I concur regardless of the outcome, you will have better results and less headaches if you replace the motors; well worth the effort and cost in this case. If you ever decide to add sound, this will be a requirement and NOT an option.
Carl in Florida - - - - - - - - - - We need an HO Amtrak SDP40F and GE U36B oh wait- We GOT THEM!
I guess I am going to re-think this project. My DCC system is the Digitrax Zephyr. I don't know how many amps it handles but 3 amps sounds like a lot. I plan on using sound and have 3 engines now that are sound equipped.
I have seen a modeling project for the T1 where the modeler disconnected one of the motors. I guess the reason was the same, too big of a current draw.
Now my question is could I use one motor with the other disconnected or will the performance still not measure up to replacing the motors with new can motors.
Your advice would be appreciated.
topcopdoc Once you have seen DCC and sound in action it is like moving up from a black and white TV to a color set (only the old guys like me will relate to this). Doc
Remember "It's Howdy Doody Time"? On a round screen black and white 9 or 11 inch TV screen? I sure do.
And having to have a tall tower with a yagi antenna on the roof to receive the one TV station that was in Saint Louis, MO at the time (KSD-TV). And KSD was the only TV station within hundreds of miles.
And the picture would flutter for several minutes every time an airplane got within 10 miles.