Plug a voltmeter into the cigarette lighter socket. What is the voltage when the engine is idling without the lights on?
If it reads around 13.8V to 14.4V the battery is charging.
Less than this voltage and you may have a charging problem.
Here's one on ebay.
Car voltmeter LED
Make sure you have a good automatic car battery charger. This Bosch is good as it is simple to use, yet won't overcharge your battery. Beware of cheap car battery chargers, as they can't detect when the car's battery is full, so will just keep charging when the battery is full thereby causing permanent damage...resulting in a new battery being needed.
I've linked to this Bosch C1 on the German version of Amazon, because it's about half the price of the same battery charger that is sold on the UK version of Amazon.
Bosch C1 12V Battery Charger
If it reads around 13.8V to 14.4V the battery is charging.
Less than this voltage and you may have a charging problem.
Here's one on ebay.
Car voltmeter LED
DC 12V/24V LED Digital Car Vehicle Battery Voltage Meter Tester Voltmeter | eBay
Greater than 12.0 (12V CAR) OR 24.0 (24V CAR). For DC 12V or 24V Car. Between 26.0 TO 28.0 (24V CAR). Between 13.5 TO 14.5 (12V CAR). With high brightness of LED there is no difficulty in seeing the display.
www.ebay.co.uk
Make sure you have a good automatic car battery charger. This Bosch is good as it is simple to use, yet won't overcharge your battery. Beware of cheap car battery chargers, as they can't detect when the car's battery is full, so will just keep charging when the battery is full thereby causing permanent damage...resulting in a new battery being needed.
I've linked to this Bosch C1 on the German version of Amazon, because it's about half the price of the same battery charger that is sold on the UK version of Amazon.
Bosch C1 12V Battery Charger