7.  WHAT DO I LOOK FOR IN BUYING A NEW BATTERY?

Battery buying strategy for use in Canada, for example, is different than in the hot climates found in Texas.  In the colder climates, higher CCA ratings are more important.  In a hot climate, higher RC ratings are more important than CCA; however, the CCA rating should be satisfied or just exceed your vehicle's OEM (Original Equipment Manufacturer) cranking amp requirements. Here are the major buying considerations:

7.1. Type

When selecting the starting battery type, it is important that you select one that will match the voltage output of your vehicle's charging system. The easiest way to accomplish this is to replace your battery with the same or compatible type of battery that originally was installed in your vehicle. If you change your replacement battery type, you might have to modify the charging system to prevent under or over charging. For example, replacing a Wet Maintenance Free with a Wet Low Maintenance battery. The five most common types of starting batteries are:

7.1.1. Wet Low Maintenance

The wet (or flooded) low maintenance batteries have a lead-antimony/ calcium (dual alloy or hybrid) plate formulation. Some battery manufacturers, such as Johnson Controls, build "North" and "South" battery versions to make up for the differences in cold and hot climates. For off road applications in trucks, recreational vehicles (RVs), motor caravans, 4x4's, vans or SUV's (Sport Utility Vehicles), some manufacturers build "high vibration ", commercial, or RV battery versions designed to reduce the effects of moderate vibration. Some also construct special batteries that have a higher tolerance to heat by changing plate or connecting strap formulations or providing for more electrolyte.

If you replace a sealed maintenance free battery in a GM vehicle, such as an ACDelco, with a non-sealed lead-antimony or lead-antimony/calcium low maintenance battery, you will need to check the electrolyte levels more often.  This is because GM sets their voltage regulators at higher charging voltage, 14.6 to 14.8 volts, to recharge the sealed maintenance free lead-calcium/calcium batteries.

7.1.2. Wet Maintenance Free

Maintenance free batteries have a lead-calcium/calcium formulation, for example, Delphi's ACDelco. The advantages of maintenance free batteries over low maintenance are: less preventive maintenance, up to 250% less water loss, faster recharging, greater over charge resistance, reduced terminal corrosion, up to 40% more life cycles, up to 200% less self discharge, and less danger to consumers because there is less to service.  However, they are more prone to deep discharge (dead battery) failures due to increased shedding of active plate material and development of a barrier layer between the active plate material and the grid metal.  If sealed, a shorter life in hot climates is often experienced because water cannot be replaced.  Maintenance free batteries are generally more expensive than low maintenance batteries.

7.1.3. Sealed Gas-Recombinant AGM (Absorbed Glass Mat)

AGM GRT (Recombinant Gas Technology) batteries have all of the advantages of the maintenance free batteries plus a lower self- discharge rate; longer life; a higher resistance to vibration, deep discharge failure, and heat; and can be used inside a passenger compartment. This is because vehicle manufacturers want to extend their "bumper-to-bumper" warranty periods, to relocate the battery from under the hood to avoid temperature extremes, to provide more weight in the rear, or to save under-hood space. They are more expensive than maintenance free starting batteries. In the future, you can expect AGM batteries in the $80 to $120 price range.

Examples of AGM batteries are Concorde's Lifeline, Delphi's Freedom Extra, and ACDelco's Platinum. An AGM battery can normally replace a wet low maintenance battery, but a wet low maintenance battery normally cannot replace an AGM battery without possibly adjusting the charging voltages. Expect to see 36-volt AGM car batteries with 14/42-volt dual or 42-volt electrical systems introduced by some of the car manufacturers in 2003.

      

[Source:  Hawker]

The following graph is a comparison of the total number of life cycle vs. average Depth-of-Discharge for a gel cell and AGM battery.

[Source: Concorde]

7.1.4. Sealed Spiralcell® GRT AGM

For excessive vibration applications in off-road operation or extreme conditions, it is best to use a Spiralcell® AGM battery because it is sealed and there is no shedding of active plate material since the plates are immobilized and longer life. In addition, it has all of the advantages of the AGM starting battery, maintenance free, smaller, faster recharging time, and does not require special shipping. Examples of Spiralcell® AGM batteries are Optima and Exide's Select Orbital.

Exide Select Orbital Construction

[Source:  Exide]

7.1.5. Marine Starting

A "dual" or starting marine battery is a compromise between a starting and deep cycle battery that is specially designed for marine applications.  A deep cycle or "dual marine" battery will work as a starting battery if it can produce enough current to start the engine.  For saltwater applications, sealed AGM or gel cell batteries should be used to prevent the formation of DEADLY chlorine gas

Starting batteries are specially designed with thinner and more plates for high initial amp applications and shallow discharges.  Cars usually start within 15 seconds and typically consumes 1%-3% of the battery's capacity. Car batteries should not be discharged below 90% State-of-Charge.  By contrast, marine starting batteries are designed for prolonged discharges at lower amperage that typically consumes between 20% and 50% of the battery's capacity. Deep cycle batteries typically are discharged in a range of between 50% and 80% of the capacity.

7.2. CCA (Cold Cranking Amps)

The second most important consideration is that the battery's CCA rating meets or slightly exceeds, your car's OEM cranking requirement, for your climate.  CCA are the discharge load measured in amps that a new, fully charged battery, operating at 0° F (-17.8° C), can deliver for 30 seconds and while maintaining the voltage above 7.2.  Batteries are sometimes advertised by their CA (Cranking Performance Amps), MCA (Marine Cranking Amps) measured at 32° F (0° C), or HCA (Hot Cranking Amps) measured at 80° F (26.7° C). These measurements are not the same as CCA.  Do not be misled by the higher CA, MCA or HCA ratings.  To convert CA to CCA, multiply the CA by 0.8.  To convert HCA to CCA, multiply HCA by 0.69.

To start a four cylinder gasoline engine, you will need approximately 600-700 CCA; six cylinder gasoline engine, 700-800 CCA; eight cylinder gasoline engine, 750-850 CCAs; three cylinder diesel engine, 600-700 CCA; four cylinder diesel engine, 700-800 CCA; and eight cylinder diesel engine, 800-1200 CCA. To convert CCA, a SAE (Society of Automotive Engineers) standard, to an EN, IEC, DIN or JIS standard, please refer to the conversion table found at www.midtronics.com

In hot climates, buying batteries with double or triple the cranking amps that exceeds your starting requirement is a waste of money.  However, in colder climates the slightly higher CCA rating is better, due to increased power required to crank a sluggish engine and the inefficiency of a cold battery.  As batteries age, they are also less capable of producing CCA. According to the BCI (Battery Council International), diesel engines require 220% to 300% more current than their gasoline counterparts and winter starting requires 140% to 170% more current than the summer. These increased requirements are account for in the OEM CCA recommendation.

[Source:  Exide]

If more CCA capacity is required, two identical 6-volt large starting batteries can be connected in series or two identical 12-volt starting batteries can be connected in parallel.  Please refer to the diagrams in Section 7.2 below for more information about connecting batteries in series and parallel.  If you connect two 12-volt batteries in parallel, and they are identical in type, age and capacity, you can potentially double your original capacity.  If you connect two that are not the same type, you will either over charge the smaller of the two, or you will under charge the larger of the two. Connecting two batteries in series is better that two in parallel. Within a BCI group size, the battery with more CCA will have more plates because a larger surface area is required to produce the higher current.

7.3.  Reserve Capacity (RC)

The third most important consideration is the RC (Reserve Capacity) rating because of the effects of increased parasitic (ignition key off) loads while long term parking and emergencies.  RC is the number of minutes a fully charged battery at 80° F (26.7° C) can be discharged at 25 amps until the voltage falls below 10.5 volts.  European and Asian starting and deep cycle batteries are usually rated in Ampere-Hours.  To convert Reserve Capacity and Amp hours, check the battery manufacturer's specifications. More RC is better in every case!  In a hot climate, for example, if your car has a 360 OEM cold cranking amps requirement, then a 400 CCA rated battery with 120 minutes of RC and more electrolyte for cooling would be more desirable than one with 600 CCA with 90 minutes of RC. There is also a relationship between the weight of the battery and the amount of RC. A heavier battery has more lead and is better.

The following Concorde graph shows the effects of temperature vs. percentage of capacity:

CAPACITY vs. TEMPERATURE

[Source:  Concorde]

Adding more Reserve Capacity can be done in three ways.  The best way is to add a deep cycle battery and a diode isolator to your existing starting battery.  This is a standard setup in most RVs (Recreational Vehicles).  The advantage of this multi-battery setup is that the high-powered accessories can be connected to a deep cycle battery (or batteries) and the car battery is available to start the engine.  A second advantage of using a deep cycle battery to power the high-powered accessories is that it can be discharged and recharged hundreds of times without damaging the battery.  A starting battery is not designed for deep discharges and will have a very short cycle life if it is abused by deep discharges. A third advantage is that both batteries will be recharged automatically when the charging system has power available. 

A second way of increasing Reserve Capacity is by replacing the existing car battery with two identical larger six-volt deep cycle batteries connected in series or a larger, 12-volt deep cycle battery. The deep cycle batteries must have enough cold cranking amps to start the engine in your climate. The third way of increasing Reserve Capacity is by connecting two identical 6-volt large starting batteries in series or two identical 12-volt starting batteries in parallel.  Please refer the diagrams below for more information on connecting batteries in series and parallel.  If you connect two 12-volt batteries in parallel and they are identical in type, age and capacity, you can potentially double your original capacity.  If you connect two that are not the same type, you will either over charge the smaller of the two, or you will under charge the larger of the two. Connecting two 6-volt batteries in series is always better that two 12-volt batteries in parallel.

The recommended parallel and series connections are as follows:

  

[Source: Interstate Batteries]

By connect this way, the batteries will discharge and charge equally.  When connecting in series or parallel and to prevent charging problems, do not mix old and new batteries or ones with different types or capacities.  Battery cable lengths should be kept short and the cable diameter should be sized large enough to prevent significant voltage drop (.2 volts (200 millivolts) or less) between batteries.

7.4. Size

Manufacturers build their batteries to an internationally adopted Battery Council International (BCI) group number (24, 34, 35, 65, 75, 78, etc.).  These specifications, which are based on the physical case size, terminal placement, type and polarity is used primarily in North America. In Europe, the EN, IKC, Italian CEI, and German DIN standards are used. In Asia, the Japanese JIS standard is used. The OEM battery group number is a good starting place to determine the replacement group.  Within a group, the CCA and RC ratings, warranty and battery type will vary within models of the same brand or from brand to brand. Batteries are generally sold by model, so the group numbers will vary for the same price.  This means that for the same price, you can potentially buy a physically larger battery with more CCA or RC than the battery you are replacing.  For example, a 34/78 group might replace a smaller 26/70 group and give you an additional 30 minutes of RC.  If you buy a physically larger battery, be sure that the replacement battery will fit, the cables will connect to the correct terminals, and that the terminals will NOT touch metal surfaces such as the hood when it is closed.

BCI and the battery manufacturers publish application selection guides that contain OEM cold cranking amperage requirements and group number replacement recommendations by make, model and year of car, battery size, and CCAs and RC specifications.  You can also find BCI size information online at www.exidebatteries.com and some of the selection guides at www.uuhome.de  Manufacturers might not build or the store might not carry all the BCI group numbers.  To reduce inventory costs, dual terminal "universal" batteries that will replace several group sizes are becoming more popular and fit 75% or more of cars on the road today.

7.5. Terminals

There are six types of battery terminals: SAE Post, GM Side, "L ", Stud, combination SAE and Stud, and combination S.A.E Post and GM Side.  For automotive applications, the SAE Post is the most popular, followed by GM Side, then the combination "dual" SAE Post and GM Side. "L" terminal is used on some European cars, motorcycles, lawn and garden equipment, snowmobiles, and other light duty vehicles.  Stud terminals are used on heavy duty and deep cycle batteries.  The positive SAE Post terminal in slightly larger (by 1/16 inch;) than the negative one.  Terminal locations and polarity will vary.

[Source: BCI]

Battery manufacturers or distributors will often "private label" their batteries for large chain stores.  An alphabetical list in order of the largest battery manufacturers/distributors and some of their brand names, trademarks and private labels maybe found at www.uuhome.de or email Bill Darden at bjb_darden@yahoo.com. Ownership, branding, Web addresses and telephone numbers are subject to change.  Exide is the largest battery manufacturer in the world, and Johnson Controls is the largest manufacturer in the Americas.

7.6. Freshness

Determining the "freshness" of a battery is sometimes difficult. Never buy a non-sealed wet lead-acid battery that is more than three months old or a sealed wet lead acid battery that is more than six months old. This is because it has started to sulfate, unless it has periodically been recharged or it is "dry charged".  The exceptions to this rule are AGM and Gel Cell batteries that can be stored up to 12 months before the State-of- Charge drops below 80%.  Please see Section 16. for more information on sulfation.  Dealers will often place their older batteries in storage racks so they will sell first.  The fresher batteries can often be found in the rear of the rack or in a storage room.  The date of manufacture is stamped on the case or printed on a sticker.

Some of the manufacturer's date coding techniques are as follows:

7.6.1. Delphi (ACDelco) and some Sears DieHard

Dates are stamped on the cover near one post. The first number is the year. The second character is the month A-M, skipping I. The last two characters indicate geographic areas. For example 0BN3=2000 February.

[Source:  Interstate Batteries]

7.6.2. Douglas

Douglas uses the letters of their name to indicate the year of manufacture and the digits 1-12 for the month. D=1994 O=1995 U=1996 G=1997 L=1998 A=1999 S=2000 For example S02=2000 Feb.

7.6.3. East Penn, Exide (Champion), and Johnson Controls Inc. (Interstate and some Sears DieHard)

Usually on a sticker or hot-stamped on the side of the case. A=January, B=February, and the letter I is skipped. The number next to the letter is the year of shipment. For example B0=Feb 2000.

[Source:  Interstate Batteries]

7.6.4. Exide (some Sears non-Gold DieHards)

The fourth or fifth character is the month. The following numeric character is the year. A-M skipping I. For example RO8B0B=Feb. 2000.

[Source:  Interstate Batteries]

If you cannot determine the date code, ask the dealer or contact the manufacturer.  Because of sulfation, fresher is definitely better and does matter.

7.7. Warranty

As with tire warranties, battery warranties are not necessarily indicative of the quality or cost over the life of the battery.  Some dealers will prorate warranties based on the list price of the bad battery, so if a battery failed half way or more through its warranty period, buying a new battery outright might cost you less than paying the difference under a pro rated warranty.  The exception to this is the free replacement warranty and represents the risk that the manufacturer is willing to assume.  A longer free replacement warranty period is better.

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