Canon BJ-20 User Manual page 80

When the battery pack is fully charged, the POWER indicator goes off,
4
and the printer turns off automatically. Recharge takes about 4 hours
or less.
5
Leave the battery pack switched on.
When the battery pack is switched on and the printer connected to an
AC outlet, the printer will automatically use the AC power. To use the
battery, simply disconnect the AC adapter.
If battery life becomes shorter
When you always recharge the NiCd battery pack before it is completely
exhausted (i.e. before the low battery warning is reached, page 105),
after this is done several times, the battery capacity is reduced to the
level you always use, causing the battery pack to operator for a shorter
time (and to output fewer number of prints per charge.)
A full recharge can typically deliver about 40 prints of A4-size paper. If
you can print only up to about 30 prints/A4 or so, the problem has
probably occurred. To remedy, fully charge the battery pack. Then try to
print - as much as your printing situation allows - in HQ mode until the
low battery alarm warning is reached. Finally, recharge the battery pack
to restore the maximum capacity.
Cautions
Do not overcharge the battery pack.
Do not disassemble the battery pack.
Do not dispose of the battery pack in fire. It may explode.
Keep foreign objects out of the battery compartment. They
can damage the battery and the printer.
Do not touch the terminals of the battery pack.
If the battery pack is not used, switch if off.
When the pack is being charged, the printer cannot print.
Follow local regulations when disposing of a used NiCd
battery pack.