Firstly, you need to determine the battery size or group i.e. the battery size that will best fit the physical dimensions and terminal locations for your application
If you live in colder climes, then consideration needs to be given to the Cold Cranking Amps (CCA), which define a battery's ability to start an engine in cold temperatures. The rating refers to the number of amps a 12-volt battery can deliver at -17C (0F) for 30 seconds while maintaining a voltage of at least 7.2V
Consideration then needs to be given to:
• Maintainability/serviceability – most of our batteries are tucked away in a quite difficult to access location and most us do not look at the battery until it goes flat, therefore consider a battery that requires minimum maintainance i.e. a sealed gel or AGM type battery
• Use of the vehicle – is it used daily, only in fair weather or once a year, this will reflect on battery selection
• Mechanical aptitude of the owner – an owner that is less mechanically adept, is more likely to never look at the battery until it is dead
• Battery age – take care when purchasing a battery that the manufacturing date is within the past 6mths. This is usually on the case or label and is indicated by letters and digits; A = January, 0=2000, 1=2001, etc.
• Electrical devices – is there an electric clock, that runs even with the ignition off
• Isolation – is the battery able to be totally isolated
• Wiring – age and condition of the wiring and connections; are they in good condition, no corrosion, all connections are tight, etc.
Once you have determined the above and the selection has been made I would recommend fitment of a charger/maintainer like the C-TEK MXS 3.8 (
https://www.ctek.com/products/vehicle/mxs-3-8).
These can be directly wired to your battery, with a small 10x12x30mm sealed waterproof and dust-proof connection discreetly located for easy access. I my case access is through the engine side vent; when the car is not in use the C-TEK is permanently connected (sometimes for several months) and when disconnected the connector is pushed back through the vent out of sight