Sony ClearScan25 SPP-M100 Operating Instructions Manual page 12

Step 3: Preparing the battery pack (continued)
To check the battery power
When you press (BATT CHECK), the lamps light up momentarily.
The battery lamps show the battery power: three lamps lit mean full
power and no lamp lit means no power (see below).
If only one lamp lights, the battery has little power, replace the handset
onto the base unit to charge it as soon as possible. However, it isn't
necessary to wait until the battery becomes weak. You can charge the
battery at any time at your convenience. This is because the battery
pack is a unique lead acid type, which doesn't suffer from the
"memory effect" common with nickel-cadmium batteries.
Battery lamps
(BATT CHECK)
When to purchase a new battery pack
If the battery lasts only a few minutes even after 10 hours of charging,
the usable life of the battery has expired and needs replacement.
Contact your local Sony authorized dealer or service center, and ask
for Sony BP-T40 rechargeable battery pack.
EN
12
Getting Started
Full power
Some power
Little power
No power