Denso BHT-500B User Manual page 32

BHT-500B
Power for the CU-521 can be obtained from a USB connection port (host computer or hub),
 Note 
however, charging is not possible while the host computer is in suspend mode. Charging is
resumed when suspend mode is exited. This can be avoided using a dedicated AC adapter to
supply power. Suspend mode is a power saving function used to temporarily put the computer on
standby when not in use.
5.
Place the BHT on the charger.
The LED illuminates in red and charging begins.
After placing the BHT on the charger
 Point 
when using the BHT for the first time or
when left unused for long periods of time,
do not remove from the charger for
approximately 10 minutes.
The BHT is equipped with a back-up battery used to back-up the internal memory and calendar
 Note 
clock. The internal back-up battery is charged first when charging is commenced.
Do not remove the BHT from the charger for at least 10 minutes when using the BHT for the first
time or when using after long periods of time.
16
Red LED ON