Battery End-of-Life Indicator

What it is

Quartz watches from Seiko, Citizen, Tissot and most Swatch Group brands have an "EOL" function — when battery voltage drops below threshold, the seconds hand starts ticking in 2 or 4-second jumps instead of 1-second smooth ticks.

Why

Gives you a 2–3 week warning before the watch stops entirely. You have time to schedule a battery change.

What to do

• Note the date you first see the jump.
• Take to a watchmaker within 2 weeks.
• Don't leave the watch unworn for a month with a dying battery — leakage risk.

Not all quartz watches have EOL — cheaper Casios just stop without warning.