Charging 
The optional USB charger provides a convenient way to 
charge two NiMH batteries from any powered USB port  
(for example, from a laptop computer). 
1.  Place the rechargeable batteries in the charger and 
plug it into a USB port. The blue LED on top of the 
charger starts to blink. 
2. When the LED stops blinking and stays on, the 
batteries are charged. The charging time is several 
hours for two fully discharged NiMH batteries. 
If you are not using a Vaisala-supplied charger and 
rechargeable batteries, read and follow the 
manufacturer’s own charging instructions. 
 
 
Do not attempt to charge non-rechargeable 
(alkaline or lithium) batteries!  Doing so leads to a 
risk of battery leakage, equipment damage, and 
risk of explosion and/or fire.