Extreme temperatures are hard on your battery. Ideally you would always use your battery at room temperature. At 73 F your battery should retain over 90% capacity up to 500 cycles. But that’s not practical and the BatPak is intended to be used outdoors.
The specification for charging temperature is 32 F to 113 F. It will perform well at the higher temperatures but the internal resistance of batteries rises when cold which prolongs the charge times. And the extreme temperatures when charging will negatively affect the battery life. For best results and longevity, you should keep your charging temperature in the range of 50 F to 86 F.
NEVER CHARGE THE BATPAK BELOW FREEZING. Charging below 32 F will damage the battery.
The discharge temperature is more liberal at -4 F to 140 F. That’s good news if you’re using it outdoors. As with discharging, extreme temperatures will impact performance. The lower temperatures will reduce the capacity and thus run time when powering Ra. While the BatPak will perform well at the higher temperatures, it reduces the battery longevity. To maximize the battery life and performance, the same moderate temp range of 50 F to 86 F is best.
Proper storage of the BatPak will maximize its longevity. Do not store your BatPak while fully discharged. When you have depleted the charge, restore it partially as soon as possible. Storing a fully depleted battery will shorten its life and if stored long enough, will prevent you from waking it up. It’s recommended that you store your battery at about 40-50% of capacity. Store the BatPak at moderate temperatures (50F to 86F). It’s especially important to avoid storing at high temperatures for prolonged periods.
In summary, never charge your BatPak below freezing and don’t store it fully depleted of a charge. If you care for your BatPak as outlined here, you should get 300-500 cycles before the capacity drops below 80% which will likely be about 2-3 years. It should last longer, however, the capacity will continue to drop over time and cycles to where it eventually becomes more practical to replace it.