Flat Battery or Faulty Alternator? Test Before Buying Parts
Slow cranking and repeated flat batteries can have several causes. A useful tester helps separate low charge, battery failure and charging-system trouble.
01
Pick the right level of tester
Best compact digital
Sealey BT105 12V Tester
A compact LCD option for straightforward 12V battery and charging checks.
View BT105 →
Simple LED check
Laser 2274 12V Tester
A clear LED indication and magnetic back for quick basic garage checks.
View Laser 2274 →
12V & 24V
Laser 8873 Diagnostic Tester
Adds 24V capability for a wider range of compatible vehicle applications.
View Laser 8873 →
Advanced option
Sealey BT2011 Start/Stop Tester
Designed for more detailed battery, alternator and starter testing on compatible systems.
View BT2011 →
02
Test in a sensible order
- Switch off the ignition and electrical loads.
- Inspect the case, cables, clamps and earth points for damage or corrosion.
- Do not test, charge or jump-start a visibly damaged or frozen battery.
- Connect the tester exactly as its instructions specify.
- Compare resting, cranking and charging results rather than trusting one reading.
- Use vehicle-specific information where smart charging makes the result unclear.