Last Updated on October 28, 2007
8.1. Installing Car and Marine Starting Batteries
8.2. Installing Deep Cycle Batteries
While working with car or deep cycle lead-acid batteries, please wear glasses to protect your eyes in the unlike event of an explosion. Do NOT install wet lead-acid batteries in confined area where there is ANY possibility that salt water can mix with the battery's electrolyte, like the bilge of a boat, because DEADLY chlorine gas is produced.
In a 2003 marketing study in the U.S., consumers (or non-professional battery installers) installed almost 60% of the approximately 82 million replacement car batteries that were made in 1999. Car batteries were the fourth most popular item purchased among auto parts. The same study indicated that Wal-Mart (EverStart) has surpassed Sears (DieHard) as the number one car battery seller in the United States with Auto Zone (DuraLast) as the most popular of the U.S. auto parts stores for car batteries.
Below are some questions you need to ask yourself because the installation of a replacement battery and disposal of the old one is usually included in the purchase price at some auto parts and battery stores:
If you decide to proceed, following is a list of easy steps to replace your battery and assumes that there the electrical and charging systems are in good condition:
8.1.1. In a well ventilated area, fully charge and test the new battery. Please see Section 9 for charging and Section 4 for testing the battery. If the battery is dry charged (shipped with out electrolyte), add the electrolyte but do not overfill, let stand for approximately one hour, and then slowly charge the battery at no more than 1% of the CCA or 10% of the amp hour capacity. Please see Exide's How To Charge a Dry Battery for additional information.
8.1.2. If a non-sealed wet battery, check the electrolyte levels after the battery has reached room temperature and "top off" to the proper level with distilled, deionized or demineralized water as required, but do not over fill. The plates need to be covered with electrolyte at all times to prevent an internal battery explosion or sulfation. (Please see Section 3.2 for electrolyte fill level information.)
8.1.3. Thoroughly wash and clean the old battery, battery cable lugs (connectors) and tray (case or box) with warm water to minimize problems from acid or corrosion. (Please see Section 3.3 for more information on corrosion.)
8.1.4. Mark all of the battery cable lugs or terminals so you will know how to reconnect to proper battery post and check the cables and cable lugs closely for damage. A loose terminal connection, corrosion, bad crimp (in especially a battery cable lug with multiple wires into it), or cut cable will cause high resistance and a large voltage drop when high current is running though it. If the cables are reversed, you can do extensive damage to your electrical system.
8.1.5. To prevent voltage spikes from damaging electronic equipment such as the emissions computer and to save the radio station presets, emissions computer and security code settings, temporarily connect a second 12-volt battery in parallel to the electrical system before disconnecting the first battery. If active when the key is off, a cigarette lighter plug can be used to easily connect a 12-volt parallel battery. Cigarette lighter adapters are available at electronics stores and "Computer Memory Saver" with a 9-volt battery are available at some auto parts stores, like JC Whitney for about $10.
8.1.6. Turn off the ignition switch, all electrical switches and breakers and electronic and electrical accessories and appliances. Do not use a hammer on the battery cable terminals or posts. Remove the grounded cable first because this will minimize the possibility of shorting the battery when you remove the other cables. The grounded cable is normally the NEGATIVE (-) cable, but it could be the positive cable in some older vehicles. Secure the grounded cable so that it cannot "spring" loose and make electrical contact. Next remove the remaining cable which is normally POSITIVE (+). Please remember that the battery terminal connector on the end of the POSITIVE (+) battery cable maybe "hot" (or have voltage on it from a parallel battery), so put it in a small plastic bag or cloth around it so that it will not touch the metal frame or engine components.
8.1.7. Carefully lift the old battery out and dispose of it by exchanging it when you buy your new replacement battery or by taking it to a recycling center. For additional information on recycling batteries, go to http://www.batterycouncil.org/recycling.html. Please remember that batteries contain large amounts of harmful lead, acid and other chemicals, so take great care with safety and please dispose of your old battery properly to protect our fragile environment.
8.1.8. After removing the old battery, insure that the battery tray or box and cable lugs are clean. Auto parts or battery stores sell an inexpensive brass wire brush that will clean the inside of post lug clamps and the post terminals. If the terminals, cables or hold-down brackets are corroded, replace them. A broken hold down bracket will cause excessive battery vibration and that will cause a premature battery failure. Replace any battery cables that are corroding, swelling or other damage with equal or larger diameter cable. Larger cable is better because there is less voltage drop. Please see Exide's Voltage Drop in Cables or Voltage Drop in Connections for additional information.
8.1.9. Check the positive and negative terminal markings on the replacement battery and position it so that the NEGATIVE (-) cable will connect to the NEGATIVE (-) terminal. Reversing the polarity of the electrical system can severely damage or DESTROY it. It can even cause the battery to explode.
8.1.10. After replacing and tightening the hold-down bracket, remove any plastic caps or covers on the terminals of the replacement battery, and reconnect the cables in reverse order, that is, attach the POSITIVE (+) cable first and the NEGATIVE (-) cable last. For General Motors-type side terminals, check the length of the bolt and do not tighten more than 4.2 to 5.8 foot pounds, or you could crack the battery case. For top terminals, do not tighten more than 5.8 foot pounds and 10 to 15 foot pounds for stud terminals. Connections need to be periodically checked for corrosion (or oxidation) and retightened, including the grounding cables between the vehicle's frame and engine block. If a parallel battery or "Computer Memory Saver" was used, disconnect it.
8.1.11. To prevent corrosion, coat the terminals and exposed metal parts with high temperature grease or silicone. Please see Section 3.3 for more information on corrosion.
8.1.12. Remove the parallel battery and reset all the switches and breakers, if required.
8.1.13. Test the new battery by starting your engine or with an electrical load.
Some vehicles have battery electrolyte level sensors. For Toyota and Nissan, use the sensor bypass information at http://www.exide.com/products/trans/na/battery_care/toyota_nissan.pdf and for Mazda use http://www.exide.com/products/trans/na/battery_care/mazda.pdf.
Most of the steps above for installing car batteries apply to installing deep cycle batteries with these notable exceptions. Wire sizing and cable lengths are very important because wiring that is not large enough or different lengths will cause excessive voltage loss and undercharged batteries or, in some cases, a fire. Wiring size (and fusing) should be based on the maximum possible current carried through the wire. Good sources of information for surface vehicles (RV's, trucks, etc.) for measuring maximum cable and connector voltage drops can be found at Exide's Caring For Your Battery. Please note that SAE (Society of Automotive Engineering) wire is up to 12% smaller than AWG (American Wire Gauge) wire. To better balance the voltage with batteries in parallel, wire the connections from the POSITIVE (+) battery terminals to a single positive (+) distribution point and the connections from the NEGATIVE (-) battery terminals to a single NEGATIVE (-) distribution point. All of the interconnecting leads between the battery terminals and distribution points need to be exactly the same wire size and length so the voltage is the same. For parallel and series wiring diagrams, please see Section 7.3.2. Use of bus bars is highly recommended for larger deep cycle battery bank installations.
Other good sources of information of wire sizing can be found in the Technical Information section at Ancor Products for boats and other marine applications, PowerStream or Solar Expert for solar applications. Using properly sized fuses or circuit breakers is also very important because they can provide protection for the wiring from over heating and for the electrical appliances. Good sources of basic information on connectors, fuses and wire can be found on howstuffworks or Perry Babin's Basic Car Audio Electronics Web site at http://www.bcae1.com/fuses.htm and http://www.bcae1.com/wire.htm. Most rotary A/B battery selector switches are not recommended because the heavy inrush of current during the first few milliseconds that a switch is closed can burn the contacts or arc. Series, parallel, and series-parallel battery connection wiring diagrams can be found in Section 7.3.2. Connections will need to be periodically retightened. Another good source of information on measuring for maximum voltage drops can be found at Exide's Caring For Your Battery.
Insure there is adequate ventilation for the batteries so gases can dissipate while recharging and batteries can stay cooler. In other words, do NOT use sealed battery boxes, even with sealed Gel Cell (Ca/Ca) or AGM (Ca/Ca) VRLA batteries, because if there is shorted cell, a great deal of gassing could occur. Some batteries will require up to 50 "preconditioning" cycles before they will produce their rated capacity. This is because the acid needs to fully penetrate the pores of the newly formed plates. When mixing sulfuric acid and water to make electrolyte for dry charged batteries, always slowly add the acid to the water and NEVER add water to acid as it may boil violently and splatter.