Downhole battery packs are the power source for memory logging tools and contain 5 cells or 10 cells. They are placed in a thin-wall fiberglass tube, and are available with a maximum temperature specification of 302°F (150°C), 329°F (165°C) and 356°F (180°C). When the temperature rate is higher, the output current is lower, especially when the batteries are cold. The batteries can be supplied with different types of connections. The battery packs are used in combination with a MBH.