Charging problem
Dead Battery
When your battery won't hold a charge or fails a load test, charging may not fix it. Learn when to recharge vs replace.
Is the battery dead or just flat?
A flat battery has been discharged (e.g. lights left on, short trips) but can still accept and hold a charge. A dead battery no longer holds a useful charge: it may charge up but quickly drop below 12V, or fail a load test. Age (often 4–5+ years in the UK), repeated deep discharge, and sulphation are common causes of 'dead' batteries.
If you are not sure, try a full recharge with a smart charger and then check the voltage after 12–24 hours with the engine off. If it stays above 12.5V, the battery may still be serviceable. If it drops quickly or fails a load test, replacement is the safe option. Use our Battery Fitment Finder to match a new battery to your vehicle.
- Flat = discharged but recoverable; dead = won’t hold charge or fails load test.
- Recharge with a smart charger first; retest voltage after 12–24 hours.
- If voltage drops or load test fails, replace the battery.
Problem this addresses
Battery won't hold charge or is dead
Recommended tool
Use our charger tools to confirm the right charger or check compatibility for your battery.
Open battery type detectorRelated charging guides
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Recommended chargers
Smart chargers and maintainers that work with car, van, motorcycle and leisure batteries. Check AGM/EFB compatibility for Start/Stop vehicles.
CTEK
CTEK MXS 5.0 Smart Charger
Advanced 8-step charging with automatic reconditioning for dead batteries. The gold standard for battery maintenance.
Best for:
- •Vehicles parked for weeks at a time
- •Maintaining battery during winter
- •Recovering deeply discharged batteries
Prices and availability vary by supplier. Always check compatibility with your battery type.
CTEK
CTEK CS ONE Battery Charger
Compact APTO adaptive charging for cars, motorcycles, leisure and marine. One-button operation, AGM/EFB compatible.
Best for:
- •Start/Stop and AGM batteries
- •Motorcycles and leisure batteries
- •Simple one-button charging
Check compatibility with your battery type (AGM/EFB/lead-acid).
NOCO
NOCO Genius 5 UK Smart Charger
6V/12V 5A smart charger with Force Mode for dead batteries and desulfation. Works with AGM, lithium and leisure.
Best for:
- •Recovering very flat or dead batteries
- •AGM, EFB and lithium batteries
- •Cars, bikes and caravans
Ensure correct voltage (6V/12V) and battery type setting.
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Next steps
Match your battery type and use case with our charger sizing guide. For product options see our best car battery chargers UK. If the battery is beyond charging, use our Battery Fitment Finder. Not sure what’s wrong? Run battery diagnostics, or browse our battery guides.