Charging Batteries 2

Lead-acid batteries fall into two camps – automotive batteries and deep discharge batteries such as for use in golf carts, trolling motors, or wheel
chairs.

The automotive batteries are cheap, but can only be drained to approximately 80% of their capacity before they start suffering damage. They are designed
to provide 30 seconds of high capacity current to start a engine.
The deep discharge batteries can be discharged to around 20% of their capacity before they start suffering damage. This is best shown by using a
good voltmeter to measure the battery charge. When it reaches approximately 10.5 volts (for a 12 V system) shut them down!
Do not confuse marine ‘deep cycle’ batteries with deep discharge batteries. They are different.

Lead Acid batteries, and nickel-hydride batteries, do not have a ‘memory’ effect where they act like they only the capacity that they were last
drained to before recharging. Ni-cads do, and after sustained use should be completely discharged before recharging.

Charging:

Lead-acid batteries should be charged with a 14.2V charge once every 6 months for approximately 3-4 hours to agitate the electrolyte within them
(otherwise it will segregate into different layers) and equalize the charge on the different plates. To maintain a charge on them, drop the charging
voltage to ~13.3 volts. In the telecom industry we call these two charging voltages ‘equalize’ and ‘float’. We also ‘equalize’ if we have been running
on batteries for any appreciable length of time and need to recharge the batteries once power returns.
NEVER allow lead-acid batteries to sit without at least a ‘float’ voltage on them for more than 6 months; otherwise, they start to deteriorate.
Do not ‘equalize’ batteries for extended periods of time; it will use up excessive amounts of water in the electrolyte and shorten battery life.
Unfortunately, most car alternators always ‘equalize’ when running.