Compaq Armada 7400 Reference Manual page 43

When a low battery condition occurs, the computer beeps every
15 seconds and the battery power light blinks.
When a low battery condition is reached, save your files and
initiate Suspend. You have approximately five minutes to resolve
the low battery condition before the computer enters the critical
low battery condition.
When a critical low battery condition occurs, the system initiates
Hibernation. It is recommended that Hibernation is enabled at all
times to safeguard against possible data loss in a critical low
battery condition.