Has anyone powered an mth subway with onboard batteries in a trailing car(s) so as too run on 2 rail track? Speculating what batteries voltage/amps might be suitable? I have no idea of the current drawn during operation of the subway sets. I realize that there would be a time limit before recharging.
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As a starting point, I'd budget 50 Watts of power to operate a subway pulling a few cars operating at modest speeds. Watts = Volts x Amps. So at 16V, you'd need about 3 Amps.
I'd look for an off-the-shelf Lithium battery-pack and charger system from a high-volume consumer tool, appliance, gadget, whatever. Typical Voltages might be 12V, 14V, 18V, etc. Typical battery-pack current ratings (in Amp-Hours) for something that would fit in a subway car would be, say, 3 Amp-Hours. So if the subway is drawing 3 Amps, the battery would last for 1 Hour. If the subway draws 1 Amp, the battery would last for 3 Hours.
You also need a minimum voltage to run MTH electronics and the typical DC motors they use in their subway sets. You might be able to squeak by with only 12V DC but that might limit speeds to, say, 20 sMPH. I'd suggest at least 16V or so.
How then are you controlling (speed, direction) the subway? Are you ripping out the MTH Protosound boards and installing some kind of direct-to-engine wireless RF system? If you search around there are decades of examples of battery-powered wireless remote train controller products - including the relatively modern Lionchief. I'm not sure if any are subway-specific with appropriate sounds if that's important.
Please elaborate on your battery power approach instead of track power. Is it impractical or too expensive to change the powered-trucks for 2-rail operation? Being a subway, are you modeling the 3rd rail and can you pick up "hot" track voltage by effectively moving the location of the center-rail power pickup?
Finally, presumably your trailing cars are lit. With conventional incandescent bulbs these can draw over 5 Watts per car. If you convert to LEDs you can get them to under 1 Watt per car essentially taking them out of the equation. Since you need some kind of wired-tether between the battery car and engine car, I suggest you include a method to transmit directional lighting end-to-end; that's one thing that's always bugged me about subway sets.
For a display. Thanx for your very informative reply!
Tommy,
If you have some time to wait. A partner of BlueRail is rumored to be coming out with a fully supportable "O" Gauge solution this summer with sound.
Check out some of their videos here Blue Rail
Ron
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