Batteries
UNDERSTAND HOW THEY WORK TO SET YOUR BOAT UP RIGHT
by MICHAEL CERDA
16
March, 2015
Lead-acid (flooded) batt-eries have been around since 1859. This battery contains 6 lead plates, separated a specific distance, and submerged in a dilute sulfuric acid.
Each lead plate generates 2.15 volts when fully charged to produce 12.9 volts in a norm-ally functioning battery.
As a battery discharges, a soft layer of lead sulfate (sulfation) begins to form on the lead plates. During normal charge cycles the sulfation gets re-absorbed into the sulfuric acid. However, if the battery is not immediately connected to a charger, the sulfation begins to harden and crystalize. In turn, the battery's charge capacity begins to decrease.
Under-charging, or over- charging a battery will also affect it's capacity. A rule of thumb when choosing a charge setting is not more than 1/5th of the Amp-hour (Ah) rating for the battery. In other words, for a 50Ah battery the highest charge rate recommended is 10 amps.
A sign of overcharging can be corrosion around the battery terminals. Gases will vent out through the top of the battery if the sulfuric acid starts to boil. The gas reacts with the term-inals, causing the corrosion.
Alternatively, loose terminals can also lead to corrosion. If corrosion is found check them first and clean it away.
Lead acid batteries need to be serviced occasionally by adding distilled water. Allowing a battery to run low reduces its charge capacity. Allowing the battery to run dry will cause the lead plates to corrode, making it unusable as it would no
longer generate electricity.
A fill-level indicator is usually stamped on the side of the battery case and should only be filled to that point. Distilled water is used instead of tap water because it doesn't contain minerals, or any other contaminants, which could increase the batteries self-discharge rate.
Over time all batteries slowly discharge, even without being connected to a load. The rate can vary from 3-20% per month depending on temperature, with higher temperatures leading to quicker discharge times.
All batteries should be charged at least every 6 months to avoid permanent sulfation damage and more often in warmer conditions.
Absorbent Glass Mat (AGM)batteries are very similar to lead-acid batteries, except the acid is encapsulated in a fiberglass mat material making
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Ohm's Law can be used to calculate each of the four components in the center of the wheel if you know at least two of the components. This simple formula is very handy calculating the load that gets applied to a battery for example. Click on the image for an online calculator.
Construction of a typical flooded lead-acid battery.