Battery Maintenance

With Christmas, winter, toys, and a time when battery replacement seems to be a forethought on our minds, I thought it apropos to write an article on battery care and maintenance.

The commercial use of the lead acid battery is over 100 years old. The same chemical principal that is being used to store energy today is basically the same as that which was used in the first Model A Ford.

If you can grasp the basics of battery technology you will have fewer battery problems with your generator and will get better performance, reliability, and longevity.

Analysis of emergency generator set failures shows that battery problems cause at least half of all failures to start. These failures don't need to happen. Generator set maintenance requirements frequently give detailed attention to the engine, the generator, and peripheral equipment but little more than voltage requirements for the starting battery. Reliability of a generator requires a good battery and charger and periodic maintenance. Proper maintenance can prevent almost all battery failures.

Battery failure can be the result of an old battery reaching the end of its expected life, but more often lead acid batteries die prematurely and suddenly because of improper charging or lack of a preventive maintenance program. A good preventive maintenance program should catch a battery nearing its end of service. All too often batteries fail to provide the expected life, because the individual responsible did not recognize and address the conditions that cause failure.

A few things on safety when working around batteries. First, remove all jewelry. After all you don't want to melt your wedding band into your finger. Also, lead acid batteries create hydrogen gas which is very explosive. One spark and you'll think Kingdom come has arrived early. I recall seeing a battery literally blow its top, drenching everything near it with sulfuric acid. So, safety goggles are strongly encouraged. Sulfuric Acid likes to eat holes in anything containing cotton, too, so don't do any battery maintenance in your good clothes. And, when doing work on a generator, always disconnect the ground cable, but not before disabling the battery charger.

The Lead Acid battery is made up of plates, lead, and lead oxide with a 35% sulfuric acid and 65% distilled water. This mixture is called electrolyte, which causes a chemical reaction that moves electrons.  Those electrons move when a load is connected, say the starting motor.

Basically there are two types of lead acid batteries; The two main types are Starting (cranking), and Deep Cycle (marine/golf cart). Sealed AGM, Gel-Cell and NiCd batteries aren't discussed in this piece. The starting battery is designed to deliver quick bursts of energy (such as starting engines) and therefore has a greater plate count. The plates are thinner and use different materials. The deep cycle battery has less instant energy, but greater for the long haul. Deep cycle batteries have thicker plates and can survive a number of discharge cycles. Starting batteries should not be used for deep cycle applications because the thinner plates are more prone to warping and pitting when discharged.

So what is CCA, CA, AH and RC you may ask? These are the battery standards used to rate the output and capacity of a battery.

Cold Cranking Amps (CCA) is a measurement of the number of amps a battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is especially important in starting battery applications, and in cold weather.

Cranking Amps (CA) is the cranking amps measured at 32 degrees F. This rating is also called marine cranking amps (MCA).

Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops below 10.5 volts.

An amp hour (AH) is a rating usually found on deep cycle batteries. If a battery is rated at 100 amp hours it should deliver 5 amps for 20 hours, 20 amps for 5 hours, etc.

Now the moment you've been waiting for; Battery Maintenance. The battery should be cleaned externally using a baking soda and water solution (with the caps on). Cable connections need to be cleaned and tightened because battery problems are often caused by corroded and/or loose connections. Batteries need to have the fluid level checked periodically. If you need to add water, use only distilled mineral free water. Minerals in the water will contaminate your cells. Don't overfill battery cells because fluid expansion migrates to the top of the battery causing a parasitic draw. To prevent corrosion of the terminals and cables use a felt washer on the posts. Also, you should coat the exposed cable end with the grease or petroleum jelly (Vaseline). The reason is gases from the battery will condense on metal parts and cause corrosion.

When it comes time to test the battery, what do you do? Good question. So, let's attack that. Though the most accurate method of testing a battery is the measurement of specific gravity and battery voltage, you can also perform a load test. However, I don't feel a load tester is necessary since your engine starter can serve as a sufficient load for a basic voltage drop test.

For any of these methods, the battery must first be fully charged and the surface charge then removed. Sitting for 12 hours (without a charge) or using a short crank cycle (without starting the generator) will do the trick. Remember, a load test can only be performed if the battery is near or at full charge. Once this is done, an Open Circuit Voltage (OCV) test can be performed.

	State of Charge	O.C.Voltage
		12V	24V
	100%	12.7	25.4
	75%	12.4	24.8
	50%	12.2	24.4
	25%	12.0	24.0
	Discharged	11.9	23.9

So, the battery and its posts are clean, the electrolyte is topped off and you've tested the OCV (Open Circuit Voltage).  There's also a voltage drop test that should be performed as well. To do this, you'll need a Digital Multimeter (preferably a Fluke 87) with a Min/Max feature.  The procedure is simple; connect the voltmeter with it set to record via the Min/Max feature and attempt to start the generator (ignition disabled) for 15 seconds. Then press the Min/Max button to view the Minimum voltage realized during cranking.  On a 12 Volt system, anything lower than 9.7 volts at 80°F lends suspicion to the battery that it may be on its way out.  On a 24 Volt system, the minimum would of course be double that of the 12 Volt system.

Battery life is dependant on many factors. Only 30% of batteries sold today reach the average 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous. Here are just a few.

• Batteries sit too long between charges. As little as 24 hours in hot weather and several 
  days in cooler weather.
• Battery is stored without some type of energy input.
• "Deep cycling" an engine starting battery. Remember these batteries can't stand deep discharge.
• Undercharging of a battery to only 90% of capacity will allow sulfation of the battery using 
  the 10% of battery chemistry not reactivated by the incompleted charging cycle.
• Low electrolyte level - battery plates exposed to air will immediately sulfate.
• Incorrect charging levels and settings. Most cheap battery chargers can do more harm than good.
• Cold weather is also hard on the battery. The chemistry does not make the same amount of 
  energy as a warm battery. A deeply discharged battery can freeze solid in sub zero weather.

Another anomaly with respect to battery failure is the effects of elevated electrolyte temperatures on lead-acid batteries shorten battery life significantly. A four year battery can lose as much as 50% of its life expectancy when ambient temperatures average 92°F over a 12 month period. Therefore, life expectancy of a lead-acid battery in the Arizona heat is less than half of the manufacturers intended life expectancy.  That is why we recommend a 2-year replacement cycle, regardless of the test results.

Before I bid you adieu, here are some battery do's and don'ts.

First, the Do's...

• Do think safety first.
• Do regular inspection and maintenance especially in hot weather.
• Do recharge batteries immediately after discharge.
• Do disable the battery charger before disconnecting the battery (overvoltage will fail a control panel).
• Do buy the highest RC reserve capacity or AH amp hour battery that will fit your configuration.

And now the Don'ts.

• Don't forget safety first.
• Don't add new electrolyte (acid).
• Don't use unregulated high output battery chargers to charge batteries.
• Don't place your equipment into storage without some type of device to keep the battery charged.
• Don't disconnect battery cables while the engine is running (your battery acts as a filter).
• Don't add tap water as it may contain minerals that will contaminate the electrolyte.
• Don't discharge a battery any deeper than you possibly have to.
• Don't let a battery get hot to the touch and boil violently when charging.

As you can see, there's a lot to a little battery and there are many points and details that I didn't write about because I wanted to keep this simple. More information, should you wish to advance your studies on batteries, can be found at http://www.batteryfaq.org/.

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