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Wild Thumper Controller Not Charging Battery Pack

First off, as this is my first post I appologise if I break any forum conventions!

I received a wild thumper chassis and controller yesterday and I'm very excited to start using it, however I'm having trouble with the battery charging part. 

To go along with the chassis and controller I ordered this battery pack (http://www.onlybatterypacks.com/showitem.asp?ItemID=10516.3)


Cell: 2200mah Sub-C Discharge rate: 25amps Wire: 22ga Rx, 14/16ga on larger connectors Size; L 2.64" x W 1.70" x H 1.76" Weight; 11oz.

Reading through the controller manual (http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Robotics/Wild%20Thumper%20Controller%20Instructions.pdf) and the included arduino code. What I expected to happen was that when I hooked up the battery pack, and plugged in my 12VDC power supply, it would start charging the battery (assuming it's low).

However as I monitored the serial out (I added a Serial.println(Volts); and a delay(250);) what I saw was the already low voltage (started out reading 45) dropping over time. I waited about 2 hours to compare readings and it had dropped to reading ~40. (So less than 1 volt)

You can see my setup below. Thoughts on what I'm doing wrong would be much appreciated!