[whynot]

When I was a young sparkie, I spent some time on routine maintenance of local substations (aka "dunny patrol"). Typical work included checking substation batteries, checking the tapchanger on the transformer, etc, and cleaning and reloading the toilet paper in the substation dunnies.

Anyway ... it was not unusual to work on substation batteries that were 20-30 years old. The reason for their long life was; wet-cell construction (and checked every four weeks), stable temperature, and lack of work. But they were expected to be able to go deep into their discharge cycle once every few months.

Back then (and this was nearly 40 years ago) topic of poor car battery life, particularly on replacement batteries, was an active discussion. Below is some advice an old tradie (in the 1980's) gave me;

* OEM batteries have great life because they are fresh from battery manufacture to car manufacture. More so if the car has not been sitting in the dealer's yard.

* Heat is the biggest killer of batteries. (At the time, Taxi were starting to appear with AC. Often cab drivers use to sit at the rank in summer with engines idling and AC running, and could kill a new battery in eight weeks).

* Charge/discharge cycles. A typical lead acid battery is good for around 300 charge/discharge cycles. Regularly going below 50% is no good for it. About once a month, it needs to be _gently_ brought back to 100%. In a car this implies a long road trip or a battery charger. Overcharging will also kill it quick.

* If a battery is staring to consume a lot of water, it is a sign that it is on its way out.

At the time, the old tradie was a big fan of the new Japanese batteries (for their manufacturing quality) and the local Century (for its robustness).