Hello Steve,
Chances are that the battery has more than done it’s time at that age - even though it starts the car. Modern cars are very susceptible to battery condition, and the old marker of ‘it starts the car’ , really no longer applies.
Don’t assume it’s serviceable, so get it tested.
Yes, Halfords were doing testing.
Buying a replacement from Halfords?? Personally not for me - a couple of issues with ones I’ve had, and that’s before you consider the price!
For me, I only buy Varta/Bosch on line from specialist suppliers, at the most competitive price, with a minimum of 4 year warranty. Suppliers include: - Battery Megastore, Tayna - there are more. Beware, strangely, some charge you carriage if bought direct, but sell off EBay at the same price with free delivery! Why??
Kind regards,
Gareth.