MX5Ireland

hi
Have been having problems with the 5 not starting even after been running for 30 mins . Brand new battery fitted less then 100 miles ago so i think the altenator is gone . How do i check this or what else could he causing this?

If you have a multi meter try checking what voltage the battery is getting with the car running. Should be getting a steady 14volts. If not check if alt belt is loose/stretched or worn.

Checking Battery/ Alternator

You can get battery checkers from tool shops/motor factors, halfords and lidl/aldi. They have LEDs on them just follow their instructions.

Or you can use a multimeter.

1 put the test needles one each termail of the battery you should get 11.8 - 12.3 volts. If you have less then your battery is has no charge and will not start the engine.

2 you have around 12volts on the battery. Start the car. The voltage should read across the battery 13.3- 14volts. If not then your alternator has issues.

3 Start some accesories, such as wipers headlights and heater fan. Again measure the voltage across the battery. You should get no lower than 13.2volts if you get something really low say 12.4 then your alternator is not working.

Checking alternator/charging problems.