So here is my take on this so take it as you will. I see 4 options here. 1. Make your own throttle out of a DPDT switch and a rheostat, run off the battery 2. Buy a commercially available DC input DC output throttle (if you can even find one any more) 3. Bypass the transformer in commercially available throttle, run off battery. 4. Use an inverter and power a power pack normally. As for the battery, get a Marine/RV deep cycle. They are designed to be run low and charged back up again, and they give out their power over a long period of time. A starting battery does not like to be drained and recharged, and it will give out power as quickly as possible. While you “can” use each type for the others job, neither will do the others job well. Recharge time is going to depend on your charger. A deep cycle battery reacts best with a charge under 10 amps, I recommend a smart charger that will detect the battery’s full charge and then drop into maintenance mode. #1 and #2 and possibly #3 will give you the longest battery life running trains, and we are going to be looking at days of constant use with 3 or 4 trains. With the inverter you will get a good 6 or 7 hours, possibly more if a train is all you are running. My old pop up camper would get about 48 hours per battery running the vent fan all day, and a couple hours of lighting at night and maybe the heater (gas heat/electric fan) if it got cold at night. It would also run the water pump when we used the sink. So using an inverter is not gonna be too bad on ya. Most of my equipment was DC powered, except the heater fan, that was AC. I still got 2 days of use per battery, with much more current draw than your trains will be doing. Also when I worked at O’Reilly’s we would use an inverter and a marine battery when the power went out to power the phones, the server and network equipment. That one battery would last us 6 or more hours. That’s a lot more draw than a railroad will be doing. Inverters are rated in MAX wattage, not average wattage. Be careful as not all are created equal. Make sure whatever you buy if you go this route has a high duty cycle, as that is a more critical rating. The Duty cycle is the time the device can be used at a given wattage before it must be shut down to cool. They usually give you a couple different wattages and the times. Let’s say you buy a 750W unit and the duty cycle is unlimited @ >200 watts, 2hrs @ 500 watts and 30 seconds at 750 watts. But there is another brand that shows unlimited @>100W, 3hrs @ 300W, and 10 seconds @750. They are not created equal, and the first one will perform better, and most likely give you better battery life. I have a portable 1000 watt inverter that must be clamped or screwed down on a battery. It’s great for most everything I have ever needed, and was only a few $$ more than the 750 watt version. 500 watts is usually the limit for cigarette lighter ports, but should power a DC throttle just fine. I preferred the larger unit for flexibility and the duty cycle number were much better than the 750W unit of the same brand.