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Why does the logger warm up when charging?

In this section:

The logger contains a nickel-metal hydride battery pack for better performance and duration. This type of battery normally heats up during charging.


The devices generate heat while charging, especially toward the end of the charging cycle. This temperature increase itself is one of the parameters used by the device to detect that it is fully charged.

Optimal ambient temperature

15° - 25°C

59°- 77°F

Ambient temperatures above 30°C / 86°F will have a negative effect on charging.

Minimum ambient temperature



The charging process automatically interrupts while the ambient temperature is outside this interval.

Maximum ambient temperature



We recommend placing loggers in an upright position when charging. If the loggers are leaning to the side and/or against each other, their temperature might increase, preventing the battery from fully charging.

The device should not be placed in a shipment directly after disconnecting from a charger. As the temperature sensor on the device is inside the USB connector cable, the device should be allowed at least 30 minutes to recover after charging for the temperature measurements to be accurate.