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subject: Tips On Choosing A Marine Battery For Your Boat [print this page]


Tips On Choosing A Marine Battery For Your Boat

The most common kind of battery in marine use today is the standard lead acid battery. The wet cells can store a large amount of energy in a small package using just sulfuric acid. This energy is stored within lead grids mounted inside the battery. The lead explains the massive weight of lead-acid batteries.

Battery choices are further divided along three methods of construction. Currently, there are three common battery technologies: Wet-cell, Gel, and AGM.

As we stated earlier, wet-celled technology is the most commonly used battery. They offer the most size and design options and are developed for many different uses. The grids in wet-celled batteries are only supported along the edges, hence these are the weakest mechanically. And since these batteries are not sealed, you must be certain to insure you do not touch the acid when filling (chemical burns) or come in contact with sea water (chlorine gas) or create and explosion from the vented gas, hydrogen. The USCG requires that wet cell batteries be stored in an spill-proof box.

Gel cell batteries use a thickened electrolyte . So if the container is broken, the cell will continue to perform as normal. In addition, the thickening agent prevents stratification by preventing the electrolyte from splashing around. Gel cells are sealed and cannot be re-filled so controlling the rate of charge is important. Over charging will destroy them in short order..
Tips On Choosing A Marine Battery For Your Boat


AGM or Absorbed Glass Mat batteries are the latest generation of batteries. Instead of a gel, fiberglass mats hold the cells and electrolyte in place. The bond between the fiberglass mats, the lead plates and the battery housing makes them spill proof and the most impact resistant batteries on the market today. They were originally designed to be used in aircraft.

Basically, an AGM can do anything a gel-cell can, only better. However they are too sealed and charging must be carefully regulated. I currently use them on my trawler..

Absorbed Glass Mat batteries are relatively new but are rapidly getting acceptance. There are some good reasons to use them:

Absorbed Glass Mat (AGM) batteries can dispense an electrical charge at a higher rate than flooded cells.

2 - No gassing under normal conditions: Unlike wet cells, AGMs are sealed and function under pressure to recombine the oxygen and hydrogen produced during the charge process back into water. You find AGM batteries on high-end new yachts such as Hinckley, Hans Christian, Viking, Island Packet, and Broward.

If AGMs are stored in cool bilges (they can operate under water too) their lives are prolonged; Remember that for every 15 degrees over 77F, a battery's life will be cut in half

AGMs can function in any orientation (although you may lose some capacity that way) and even if a container is broken, an AGM will not leak. This should be of special importance to blue-water cruisers that could find themselves tossed around; you would not want sulfuric acid in your boat. And as always, proper tie-downs are always recommended.

AGM batteries will require no upkeep.

There is one issue that must be considered however and that is the price of an AGM battery:

Let's review prices

-Wet cell 8-D - $150.00
Tips On Choosing A Marine Battery For Your Boat


-Gel - 8-D - $250.00

-AGM - 8-D $365.00 (Marine centers have them for $501.00)

So choose the battery that's best for your needs and have fun on the water

by: Marinetrader




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