"I first got this Bat box in the (7939) Lego city cargo train. It powered the train motor very well. It managed (with struggle) to go up a very steep slope in the train track, while pulling all three trucks. I bought some Lego Power functions lights (8870) and put them at the front of the train. The Bat box powered the lights and the Train with all three trucks up the same slope. However, when I ran the lights while the train motor was running at full speed (7/7), the lights would only run at 6/7 brightness. I also bought a second one of these Bat boxes, two M motors and an Ir receiver and I put them in my train crossing (7936). I put that receiver on freq. 3, and the train receiver on freq. 2. With that done I could control the train speed and lights, then put the boom gates down, and run the train over the Train crossing.
Now for the pros and cons: Pros: -Very long battery life (only went through 2 loads of 6 AAA batteries in 3 years. -Easy to assemble and connect motors -Very powerful Cons: -Very bulky, takes up a lot of space. -Heavy (some motors aren't strong enough to pull it) Summary: Very good motor, definitely recommend it to any Lego fan."
"I can definitely say this is one of the best lego accessories i've ever bought. They fit so well into my Lego city Cargo train (7939) Now I can finally watch my train ride around my Lego town, lighting its path :) I fit it into my IR reciever in the blue slot, and now control the train moter with the red control, and the lights with the blue control (I can control the brightness with the 7 speeds) I would recommend this Lego accesory to anyone who likes to customize/think outside of the square. I'm definitely going to buy a second pair of these lights for the back of the train :)"