A cordless vacuum that used to run for twenty minutes and now dies after five is, in the overwhelming majority of cases, simply an ageing battery rather than a fault in the vacuum itself. Rechargeable batteries lose capacity permanently over hundreds of charge cycles — this is expected wear, not a defect, though there are a few things worth checking before assuming the battery needs replacing.
Why batteries degrade
Every rechargeable battery has a finite number of charge cycles before its maximum capacity drops noticeably — this is basic battery chemistry, not specific to any one brand. A battery in daily use for two to three years reaching the end of its useful life is completely normal and expected.
Common causes
| Cause | How likely | What to look for |
|---|---|---|
| Battery naturally aged out | Very common | Vacuum is more than 2–3 years old with regular use |
| Battery not fully charged | Common | Charging indicator was not showing full before use |
| Charging contacts dirty or corroded | Common | Visible grime or discolouration where the vacuum meets the charging dock |
| Using a high-power mode constantly | Common | Max/boost mode draws down charge far faster than standard mode |
| Battery stored fully depleted for a long period | Occasional | Vacuum left unused and uncharged for weeks or months |
| Charging dock or cable fault | Less common | Indicator never shows a full charge despite long charging time |
How to check it
- Confirm a full charge
Leave it on the dock for the full recommended charging time and check the indicator light shows fully charged, not just charging.
- Clean the charging contacts
Wipe both the vacuum’s contact points and the dock’s with a dry cloth — dust and grime here is a common, easily overlooked cause of poor charging.
- Test in standard mode
Boost or max power modes typically drain the battery several times faster than standard suction. If you have been using boost mode constantly, that alone can explain a much shorter run time.
- Compare against the age of the vacuum
If it is more than two or three years old and has seen regular use, ageing is the most likely explanation regardless of other checks.
When it is worth a technician or a new battery
Most cordless vacuum manufacturers sell replacement battery packs directly, and swapping one is usually a simple DIY job — often just removing a cover and unplugging a connector, sometimes literally clipping in a new pack. If the vacuum otherwise works well, replacing the battery is usually far cheaper than replacing the whole unit.
Stop and call a qualified appliance technician or electrician if you find scorched or melted wiring, smell burning, see water that has reached electrical components, or if the fault returns immediately after a repair. Never bypass a safety device — thermal fuses, door interlocks and flood switches fail for a reason, and defeating one converts a broken appliance into a fire or flood risk.
