set database: 8878 power functions rechargeable battery box

image courtesy of peeron

theme: train, power functions
year: 2009
pieces: 1
prices: us$50
minifigs: none
new train sub theme.
power functions combining high capacity battery and simplycity.
come with a rechargeable battery box.

inside has a built-in lithium polymer batteries.

rechargeabled with 8887 transformer 10V DC.

has a speed control dial for controlling motor speed.

the voltage output is 7.4 V.
overall design is good.