Location: Maintaining Flooded Batteries

Tricks to sustaining your Flooded marine battery installation for years of use

Flooded marine batteries are the default option in most marine applications. They may be a mess, they may be less efficient, but they are cheaper. If the cost is the difference between whether you are on the water, or NOT --> Go with what you got. We publish these tricks to help you get the most out of your flooded lead acid marine batteries because it helps you, not because we can sell them to you remotely, or have vested interest.

Now when dealing with deep cycle flooded lead acid batteries, a few things should be considered. These items are best summed up by a manufacturer met along the way. This gentlemen is the Vice President of a major battery manufacturer here in the United States. He raises an interesting point:
"If folks would equalize their batteries once a month, they would last 3 times as long. If folks would charge their batteries properly, they would last 2x as long. But I can't even get them to keep from forgetting to put water them."
The point is this, flooded batteries require maintenance.
To make them work for any extended period of time requires that you perform said maintenance.
Specifically, this battery maintenance consists of cleaning, charging, and watering.
Water often, always, and then do it again.
Overcome self discharge by charging often, always, and then again.
Overcome striation with routine equalization, usage vibration, and water testing.
Lets go over each part individually...

1 Water your Flooded Batteries, or buy new ones!
Sorry to be so cruel, especially if you are faced with the purchase of new batteries now because you forgot to water them. If it makes you feel better, I have done it too. The reason a battery needs water is simple, should the plates be exposed to the air, the corrode, starting immediately. The electrolyte bath returns them to the battery, as well as protecting the battery plates. Your job is to keep those plates under water, or you will do a number of bad things. You need to check the water in your batteries routinely. This routinely means once every few days when you are "CHARGING" and "DISCHARGING" them hard. Camping for 3 weeks, plan to check the batteries in the middle or twice for good measure. When you pull the boat from storage or put it back is a great time to check the batteries, and plan to water them. Every time you think about buying a lot of water to take to the lake for your personal consumption, you should think about your batteries too.

2 Self Discharge of Flooded Lead Acid Batteries.
The trickle charger was invented to specifically address flooded lead acid batteries, and their inherent instability. The average flooded lead acid battery self discharges 10% in 24 hours, and another 10% each subsequent 30 days. Starting batteries must typically be charged over 80% to start the motor. Obviously, if you plan to store your vehicles for any period of time, you need to overcome the self discharge of your battery. For marine applications this is no different, and since you store your boat for much longer period of time than you store your commuter car, it should be a though it your mind. Shore power, at your dock or marina is there to connect a battery charger on the "float setting". A solar panel and an attached trickle charger will do fine as well. If you don't do something, you will not have charged batteries when you return.

3 Equalization: Monthly Forced Overcharge.
Flooded batteries love to be equalized for 3 reasons, striation, sulfation, and self discharge. The equalization charge overcomes all three at once, in a relatively short period of time. The high charge rate forces out the sulphate crystals too by heating them under a charge situation. The agitation of the boiling, plus the heat, and the voltage all combines to destroy them over the 10 hour period. Just like a drink on the bar, electrolyte in a flooded battery separates over time. The high rate of charge in an equalization battery charging cycle boils the plates continuously, and mixes up the acid and water electrolyte solution. This mixing ensures that your battery has the right acid mix to function properly. And finally an equalization charge ensures that the self discharge starts from the highest point, forcing the most amount of power possible into the battery prior to losses. Be sure to water your batteries before and after equalization as the process is a bit, how shall we say, active.

Cleaning up after a Flooded Battery:
Part 1 the Corrosion:
You use acid to eat an acid residue. Our favorite is the Coke, Pepsi, or Dr. Pepper in your fridge. The Phosphoric acid in these items eats the corroded residue from terminals, wires, plates, battery boxes, and the like.

Part 2 Neutralizing Acid:
Sulfuric Acid is highly corrosive and toxic stuff as it comes out of a battery. To neutralize it, making it basically into a fertilizer for the yard, is as simple as adding baking soda until the bubbling stops. If you want a mathematical formula for the neutralization, it looks like this:

Step #1- Determine the quantity of acid spilled, usually in gallons.
Step #2- Determine the specific gravity , or molarity, of the acid usually provided in MSDS.
Step #3- Determine the concentration of the acid spilled usually in %.
Step #4- The weight of water is 8.34 pounds per gallon.
Once you have a good idea what each of the above is (relatively) plug them into the following formula.
Quantity of spill X specific gravity X weight of water X concentration = weight of the spill
Example: One gallon of sulfuric X 1.84 X 8.34 X 98% = 15.04 pounds of sulfuric to neutralize.

A weak, common, household base that may be used to neutralize it, is sodium bicarbonate (NaHCO3). A thorough list of bases follows. Just plan to clean up boil over and that sulfuric acid steam residue, with a cleaner and one of these neutralizing agents. Otherwise the mess in your trash will be highly corrosive, and you will be putting that directly in our landfills...

Amount of Sulfuric Acid spilled Amount of Baking Soda to Neutralize,
NAHCO3 needed. Amount in pounds.
1 gallon 25.6
2 gallons 51.2
3 gallons 76.8
4 gallons 102.4
5 gallons 128.0
10 gallons 256.0
50 gallons 1280.0
55 gallons 1408.0
100 gallons 2560.0

Various Bases for Neutralizing Acids: (some acids cause toxic byproducts with some of these bases, careful!)

Ammonium hydroxide, NH4OH, MW = 35, clear solution, synonyms are ammonia, ammonia solution, and aqua ammonia. A strong ammonia odor emanates from these liquids. Caution should be taken as these create very high vapor pressure.

Calcium carbonate, CaCO3, MW = 100, white powder, synonyms are crushed limestone and dolomite. Low heat from most acid neutralization reactions. Gives off carbon dioxide or oxygen gas as acid is neutralized.

Calcium hydroxide, Ca(OH)2, MW = 74, white powder, synonyms are slaked lime, hydrated lime, and calcium hydrate. Flammable oxygen and hydrogen gas are given off when neutralizing acids.

Calcium oxide, CaO, MW = 56, white powder, synonyms are quicklime and lime. Most economical, lowest cost, neutralizer available for most industrial applications making it a typical choice. It's power, with a maximum pH is 12.45 at 25C, enforces this. However, chemical neutralizing reactions give off flammable Oxygen gas. Home users should take care.

Magnesium carbonate, MgCO3, MW = 84, synonyms are magnesia alba and carbonate magnesium. Carbon dioxide or oxygen byproduct from neutralization reaction.

Magnesium hydroxide, Mg(OH)2, MW = 58, white powder, synonyms are milk of magnesia and magnesia hydrate. Good neutralization agent. Reasonably powerful with a pH is 10.6 at 25C. However, chemical neutralizing reactions give off flammable Oxygen gas. Home users should take care.

Potassium hydroxide, KOH, MW = 56, white flakes, synonyms are caustic potash. High heat of reaction with toxic fumes. Maximum pH is 14 at 25C.

Sodium bicarbonate, NaHCO3, MW = 85, white powder, synonyms are baking soda and sodium acid carbonate. Low heat of reaction with carbon dioxide gas emanation.

Sodium Carbonate, Na2CO3, MW = 106, white powder, synonyms are soda ash. Being the second most economical neutralization agent, caustic soda is regularly used for industrial purposes. Maximum pH is approximately 11 at 25C. Byproduct of chemical reaction is typically oxygen or carbon dioxide based.

Sodium hydroxide, NaOH, MW = 40, white powder, synonyms are caustic soda, soda lye, caustic, and lye. High heat of reaction with toxic, explosive, and flammable fumes. Maximum pH is 14 at 25C.

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