April 2002 — By Capt.
The Tao of Power
|Part 2: Neglect will lead to discharge and damage|
You also should have cleaned the terminal posts with a wire brush, coated them with white grease, and regularly wiped down the top of the battery with a neutralizing solution of baking soda and water. (This not only gets rid of any acid residue, but cleans as well. A trail of dirt can create a circuit between terminals that can eventually drain a battery.) And while the jury is still out on the pluses and minuses of storing them on a concrete floor in your garage or basement versus on wooden slats, the one thing that is sure is that neglect will lead to discharge and damage.
With lead-acid batteries you should keep the electrolyte topped off to within 1š4 to 1š8 inch below the vent/fill holes and check the state of charge with a hydrometer. (When storing, check the electrolyte level monthly; during your operating season, I’d recommend doing it weekly.) A fully charged battery will have an open-circuit charge–one read with a voltmeter after no load has been on the battery for several hours–between 12.6 and 12.8 volts and a specific gravity reading on the hydrometer scale ranging from 1.265 to 1.290 per cell at 80F. (If you’re storing your battery for an extended period of time, a trickle charge now and then will maintain this level.) A cell reading below the accepted range is most likely shorted out or damaged beyond repair, and the battery will have to be replaced.
A lead-acid battery should never be allowed to discharge to less than 50 percent of its capacity. The farther past this point the process is allowed to go and the more frequent the discharge cycles, the more long-term damage will be done to the plates. In addition, constant discharging and recharging can also damage the battery.
Sulfation is the problem. As the energy level of the battery decreases, the chemical reactions going on within produce deposits that adhere to the plates. Each time a battery is cycled–that is, discharged and recharged–a small amount of sulfate is left on the plates. The more deposits, the less surface area available for energy production. Left to continue, this leads to cell failure and eventually, a dead battery.
State-of-the-art electronic battery chargers can keep things on an even keel. And if you don’t have one of these neat gizmos as part of your boat’s electrical system, you should look into one. Equipped with fully automatic microprocessors, they will watch over your batteries like a mother hen over her chicks, including monitoring the three stages of charging: bulk, acceptance, and float.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.