I own mk 2.5. It is fitted with a 015 battery.
All manuals and guides say it should be 063 which is somewhat wider. As the battery clamp is a fixed width type, I am wondering best course of action.
It definitely needs replacing, I assume it is lead acid not gel but how would I know.
It is a second car left outside and only used occasionally.
as ever your thoughts and help are very much appreciated.
i would add that 015 batteries are not straight off the shelf
Replace the battery with the originally fitted Panasonic from the main dealer or MX5 parts. Lots of threads on this and Panasonic are the best for your car. Main dealers can usually source these overnight to collect. They also fit perfectly and connect to the breather pipe.
MX5parts are currently out of stock on the Panasonic batteries.
We bought our last Panasonic battery from the local Mazda main dealer. A bit more expensive but we saved on delivery by collecting it ourselves.
It might also be worth checking if you have a battery tray - https://www.mx5parts.co.uk/battery-tray-motorsport-mk2-25-p-3982.html. We didn’t in our car as a previous owner had fitted the wrong (larger) battery which didn’t fit if you retained the battery tray and so presumably threw it away (along with the tubing for the battery vents). The battery tray helps locate the battery and stops it sliding around.
If you don’t use the car very much you may also want to consider a conditioning battery charger such as the CTEK MXS 5.0 (other conditioning chargers are available) provided the car is parked somewhere near to a power source. Our MX5 is parked outside but by using a couple of CTEK extension leads I can plug in the charger in the garage and run the cable to the car.