I recently called out the battery replacement guy to put a new battery in the car. The battery hadn’t died but I figured with it being three years old it would die soon. The guy tested it and said it was indeed on its way out and should be replaced. He was amazed and also said he had NEVER had anyone take such a preventative measure before; every other time in his experience people only call him when the battery was already dead.
So the tip here is to write with a marker pen on a new battery the month and year of installation (because it’s easy to assume the time less than it really is) and just replace it when it’s coming to the end of its projected life and not try to squeeze the last bit of energy from it. Also find out the typical life span of that type of battery, as some are made to last longer than others.
The second tip is to keep in your kit, or in the car, the computer code if you have a car that needs to be reset when the battery has been disconnected.
A third tip is to see how hard it is to replace a battery on your car. My car has a small engine bay and the battery is surrounded with stuff and has a difficult to remove plastic cowling. Learning in advance how to change the battery can save a lot of trouble later on.
Bugs Bunny: "I speak softly, but I carry a big stick."
Yosemite Sam: "Oh yeah? Well I speak LOUD! and I carry a BIGGER stick! and I use it, too!" BAM!