MCA is the commonly used rating for marine/RV starting power. It is the number of amperes a lead acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). This lets you know how much power you have to start your boat's engine. Top of Page

This rating applies to deep cycle marine batteries. Amp hours are simply a unit of measure for a battery's electrical storage capacity. This is obtained by multiplying the current in amperes by the time in hours of discharge. For example: A battery delivering 5 amperes for 20 hours, delivers 5 amperes X 20 hours = 100 Amp Hr of capacity. Top of Page

Put another way, this rating lets you know how many amps, for how long, you can draw from your deep cycle battery.

Reserve capacity is the time in minutes that a new, fully charged battery will deliver 25 amperes at 80 degrees F and maintain a terminal voltage equal to, or greater than, 1.75 volts per cell. This rating represents the time the battery will continue to operate essential accessories if the alternator or generator of a vehicle fails. Put another way, reserve capacity is a battery's ability to sustain a minimum vehicle electrical load in the event of a charging system failure. Top of Page

These batteries are designed to provide "deep cycle" power - and that makes them very different from ordinary car batteries. Starting a car requires a high amount of energy for a short period of time (about 5 seconds). Only a small amount of the battery's capacity is used. Once the engine starts running, the battery is recharged quickly by the alternator, which carries the basic electrical load.
On the other hand, deep cycle batteries supply a relatively low amount of current for a long period of time. They are specially designed to power electric trolling motors and other electrical accessories in boats and RVs. Unlike ordinary car starting batteries, they can be run down and recharged (deep cycled) repeatedly with minimum loss of capacity.
When a car starting battery is deep cycled, it loses capacity very rapidly and in some cases has lost its useful capacity in 50 cycles (discharges and recharges) or less. These limitations make car batteries a poor investment when used for marine and RV deep cycle applications. A single deep cycle marine/RV battery will outlast 2-4 car batteries. Top of Page

Yes! Deep cycle batteries are specially designed with denser active material and thicker plates to withstand deep discharge-recharge service. They are also reinforced by envelope and glass mat separators to reduce shedding of the active material and damage from the jolting vibration of a boat on choppy water.
Car batteries, on the other hand, use porous active material and thin plates so that high-amp energy can be quickly delivered for maximum starting power. Repeated cycling weakens the positive plates and makes the active material shed from the grids. Thus, in repeated deep discharge-recharge applications, the capacity of the car battery drops below desired levels in about 50 cycles. They are not built to withstand the heavy buffeting experienced by marine batteries. They are simply designed to do a different job. Top of Page

Deep cycle batteries can be used wherever the battery is continually discharged for an extended period of time, and then recharged:
1. In boats for powering trolling motors, fish finders, depth finders, lighting and other accessories.
2. In motor homes, travel trailers, and tent campers to run accessories, radios, TVs, fans, refrigerators, etc.
3. In outboards and sailboats to power lights and accessories. Top of Page

The life of a battery is determined by a number of factors, with the most important being proper maintenance. Amount of use, proper charging and climate are other elements that also need to be considered. A battery that is stored for prolonged periods of time without use or recharging can develop sulfation on the plates which will greatly reduce the time a battery will perform. Top of Page

A graduated-float hydrometer will display the battery’s specific gravity level. A fully-charged, flooded electrolyte deep-cycle battery will have a specific gravity of 1.265 or higher. Keep in mind that some hydrometers require temperature correction to 80° F. You can check the specific gravity only in batteries that are of the "flooded" acid design with removable vent caps (accessible cells). Using a voltmeter is another option that can be used to check a battery's state of charge voltage. A fully charged deep cycle, lead acid battery will have a voltage of 12.6 volts or higher when measured across the terminals. If the battery is being discharged during the voltage test or has been discharged recently, you will read a lower voltage or state of charge than is actually available. On the other hand, if your battery is being charged when tested or has been charged within a 24 hour period, a "surface charge" effect will play a role indicating a higher voltage or state of charge than is actually available.

Some manufacturers sealed design batteries are "flooded" types and some are valve regulated lead acid (VRLA), AGM or Gel types. If you are checking a sealed or non accessible battery, it is impossible to measure the specific gravity in these battery types. Here you will have to accept the voltage meter reading as your only indicator of state of charge voltage. When using a voltmeter, if a battery has been charged or discharged in the past 24 hours, it helps to let the battery sit disconnected to "stabilize" for 24 hours. This reading will be your most accurate reading with a voltmeter.

NOTE:

Standard "flooded" lead acid batteries state of charge (SOC) is as follows:

12.6=100%, 12.4=75%, 12.2=50%, 12.0=25%, 11.7=0%.

Sealed AGM or Gel VRLA batteries have a state of charge (SOC) as follows:

12.8=100%, 12.6=75%, 12.4=50%, 12.0=25%, 11.8=0%

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The maximum service life and performance of a deep cycle battery will depend on how often if is used and how well it is maintained, including recharges. Batteries that are rated in the cycle life should deliver that number of cycles. Cycles are defined as one complete discharge and recharge. If the battery meets the daily usage requirements, you can assume that you will get one day of use for each cycle the battery is rated at. This may not apply if your battery is stored for long periods of time or if it is not well maintained. Top of Page

The battery's state of charge can be tested using a hydrometer or a voltmeter. A hydrometer will determine the specific gravity of the electrolyte in each cell, while a voltmeter will give you a voltage reading. There are some batteries that come with a state-of-charge indicator eye built in the battery's cover. Top of Page

No. But properly charging a deep cycle battery is a very important factor which can affect battery performance and life.

1. The electrical capacity of the battery charger determines how long it will take to charge your battery. In most applications, a 10-25 amp charger is recommended. First, determine the battery's state of charge using a hydrometer, voltmeter or state-of-charge indicator.
2. Check electrolyte level before charging. Add distilled or good quality drinking water if the electrolyte level is below top of the plates.
3. Follow the instructions provided with the charger. There are many chargers on the market, each with their own features.
4. Be sure the battery is completely recharged. Use a hydrometer to determine the percent of charge, following the manufacturer's instructions.
5. Recharge within 24 hours after each use. Discharged batteries can freeze.
6. Do not overcharge your battery. Overcharging causes grid corrosion and reduces battery life. A charger with a timer switch is best.
7. Do not use a fast boost charger. A slow charge is best for a deep cycle battery.
8. Unhook the charger when the battery is fully charged.

Note:  special instructions for charging of gel products

Gel products are charged according to use or application. Use in backup applications where the battery is charged continuously (float) requires a different charging method than in discharge-charge cycling applications where the battery is not continuously charged.

Float charging

The float voltage range recommended for Exide Gel product is:

Operation at elevated temperature of 122°F (50°C) requires a reduction in charging voltage to 13.2 to 13.5 volts (2.20 to 2.25 volts per cell for series connected, multi-battery strings.)

Recharge

All batteries should be recharged as soon as possible following a discharge with a constant voltage charger. However, to recharge in the shortest period of time, raise the charging voltage to 14.40 volts for a 12 volt battery (2.40 volts per cell for series strings of batteries). The charger should incorporate a current limit feature. The maximum recommended charging current for the battery is shown below:

Operation at elevated temperature of 122°F (50°C) requires a reduction in charging voltage to 13.8 volts (2.30 volts per cell for series connected, multi-battery strings.)
 
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Overcharging a battery occurs when the battery remains on charge after it has reached full charge. Overcharging causes excess heat that can cause the plates within the cells to buckle and shed their active material. Also, the battery will react to the overcharge by producing excess hydrogen and oxygen as the water within the electrolyte breaks down. The water that is lost due to overcharging can be replaced in a non-sealed battery; in a sealed battery the water loss is permanent and will negatively effect the battery's service life. Top of Page

A battery will not lose its state-of-charge strictly from placing it on a concrete surface, but will discharge it over a period of time, due simply to neglect. Top of Page

There is no real evidence that aspirin will prolong life. However, some other additives will clog up your hydrometer. Top of Page

While your battery is maintenance free, it is also maintenance accessible. For optimal performance the electrolyte level should be checked approximately every 30 days. The electrolyte level should be maintained between the top of the plates and the bottom of the vent cap openings.

In an emergency, can a deep cycle battery be used to start an outboard motor? Yes. But ONLY IN AN EMERGENCY! For maximum battery life, a two-battery system is recommended. Top of Page

Yes. Install a solid-state battery isolator to the vehicle's electrical system. This allows the trailer's batteries to be charged while driving and prevents discharge of your vehicle's starting battery. The isolator is becoming standard equipment on many motor homes. Top of Page

Clean battery case and terminals with baking soda and water, being careful to make sure the solution does not get into the battery. Always check to ensure the battery is fully charged before storing. Batteries stored in a discharged state are susceptible to freezing and an increased rate of further discharge. Store in a cool dry place (not next to a furnace or other heat source) and out of reach of children and pets. Check the state of charge every 45-60 days and add distilled water if needed. Top of Page

Exide Technologies, conscientiously applying a comprehensive business approach called Total Battery Management (TBM), plays a leading role in one of America's most effective and successful recycling programs.
TBM encompasses manufacturing and distribution of lead-acid batteries, responsible collection and storage of spent batteries, safe transportation and reclamation of battery materials, and use of those materials in the production of new batteries.
Every year, Exide recycles the components lead, acid, and plastic back to the production of new batteries. These post consumed material represent a 90+% recyclable rated. Higher recycling than lead, acid, or glass. Top of Page