A quartz clock that has started running slow, stopping intermittently, or losing a few minutes a week is almost never broken. Work through these in order.
1. Change the battery, even if it “still works”
This is the answer roughly nine times out of ten, and the reason is not obvious. A quartz movement needs a certain voltage to drive the stepper motor cleanly. As an alkaline cell ages its voltage sags under load long before it is flat enough to fail a battery tester or stop a TV remote. The motor starts missing steps — the crystal is still keeping perfect time, but the hands are not receiving every pulse.
The symptom is a clock that loses time steadily rather than stopping. Fit a fresh cell and give it 24 hours before judging.
2. Use the right kind of battery
- Alkaline, not rechargeable. A NiMH rechargeable is 1.2 V against an alkaline’s 1.5 V. Many movements will run on it, badly, and it looks exactly like the fault above.
- Not lithium, unless the maker says so. Lithium primaries hold a higher voltage for longer, which sounds better and can overdrive some inexpensive movements.
- Not a heavy-duty or zinc-carbon cell. They cannot sustain the current draw.
3. Clean the contacts
Look in the battery compartment for white or green crust. A leaked cell corrodes the spring and creates resistance, which produces the same voltage sag as a dead battery. Scrape the contacts back to bright metal with a fibreglass pen or the corner of a nail file, and check the spring still has tension.
4. Check the hands are not touching
If a clock has been knocked or shipped, the hour and minute hands can end up rubbing each other or the glass. It shows up as a clock that stops at the same point every cycle — often around the 12, where the hands overlap. Ease the minute hand up very slightly with a fingernail so there is visible daylight between the hands.
5. Check the temperature
Quartz crystals are cut to run true at around room temperature and lose accuracy as it moves away in either direction. A clock in an unheated garage or a conservatory will drift measurably, and there is nothing wrong with it.
6. Now suspect the movement
If a fresh alkaline battery, clean contacts and free hands have not fixed it, the movement itself has failed — usually a worn plastic gear or a dead coil. On most clocks this is a standard-sized module and a replacement costs very little, but the fix that matters to you is simpler: if the clock is inside its first year with us, that is a warranty claim. Email us with the order number.
A note on the ones that gain time
Gaining is far rarer than losing and usually means magnetism or interference rather than a dying battery. Move it away from speakers, motors and anything with a large transformer, and see whether it settles.
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