The problem with the battery is more than likely the connector. If you using the solid style that has the two cross cuts then you need to spread them slightly until it fits real snug in the battery. Reedy has even stated in the safety warning that comes with their batteries that the lead with the barrel connectors (they include with the battery) are only for charging.....they are the style that has the barrel shaped spring section. The spring style will not carry enough juice without getting too hot.

BulldogSRT