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Battery Terminology

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Alternating Current

The type of power sent over the grid, available in your house, or inverted from DC. In the USA this is typically 110 or 220 volts


Absorbed Glass Matt

AGM, short for Absorbed Glass Matt. Refers to batteries manufactured by using a form of Fiberglass Matt sandwiched between the lead plates. This serves to Absorb the acid, making the battery highly leak proof, and adding to its durability


Amp hours are a unit of...

Amp hours are a unit of measure for a battery's electrical storage capacity. The standard rating is an Amp rating taken for 20 Hours. What this means, say for a 100 AH rated battery is this: Draw from the battery for 20 hours and it will provide a total of 100 amps. That translates to about 5 amps an hour. 5 x 20 = 100. However, it's very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64 Amp Hours.


Discharge or Charge current...

Discharge or charge current, in amperes, expressed in multiples of the rated capacity. For example, C/10 for a 100AH battery would be 10 amps, while C/4 would be 25 amps.


Cold Cranking Amps

Cold Cranking Amps is a rating used in the battery industry to define a battery's ability to start an engine in cold temperatures. The rating is the number of amps a new, fully charged battery can deliver at 0° Fahrenheit for 30 seconds, while maintaining a voltage of at least 7.2 volts, for a 12 volt battery. The higher the CCA rating, the greater the starting power of the battery. This number is not relevant in a non-starting application!


Direct Current

The type of electrical current which a battery can supply. One terminal is always positive and another is always negative.


A generic term.

A cell with immobilized electrolyte. This is used for a number of applications. This term can suit any number of applications, including AGM and Gel


Battery Acid

A solution of sulfuric acid and water which conducts current through the movement of ions (charged particles in the electrolyte solution) between positive and negative plates. It supplies sulfate ions for reaction with the active material of both positive and negative plates.


Like trickle charge, only completely different...

Commonly referred to as trickle charge, but in reality quite different. A proper float charge will adjust the current to the battery while maintaining a pre-determined voltage level.



Gel batteries are constructed similar to standard wet cell batteries, except that the acid has a silicate stiffener that prevents the acid from vacating the lead plate



1/1000th of an amp. or, 1 amp equals 1000 milliamps


Expected operating range

The normal, expected operating range of a device.


Open Circuit Voltage

The voltage of a battery when it is not delivering or receiving power. It is 2.11 volts for a fully charged battery cell.


A measure of resistance

A measure of resistance that causes one volt to produce a current of one amp



When two or more batteries are hooked together by connecting all the positive terminals, and then all the negative terminals together. This retains the original voltage but adds together the capacity of each battery.



Reserve Capacity is a battery industry rating, defining a battery's ability to power a vehicle or device with an inoperative alternator or charging system. The rating is the number of minutes a battery at 80 degrees F can be discharged at 25 amps and maintain a voltage of 10.5 volts for a 12 volt battery. The higher the reserve rating, the longer your vehicle can operate should your alternator or fan belt fail.


What is series connection?

When batteries are connected together by connecting the positive of one to the negative of the other. The voltage of each battery adds up, but retains the same capacity


Specific Gravity

The measurement used to express electrolyte strength. SG compares the weight of the electrolyte to water, which has a SG of 1.000. A full charge should be about 1.265 per cell at 77 degrees F (25 degrees C). This changes with temperature. This cannot be measured in sealed batteries. Pure acid has a SG of 1.835. A fully discharged battery will have a SG of about 1.12. SG should not be measured right after water is added as the reading will not be accurate until the electrolyte is fully mixed. This could take hours or days - an equalization charge will speed this up considerably. The SG in many AGM batteries may be as high as 1.365, but there is no practical way to measure it.


Battery Sulfation (sul-fay-shon)

Even though Lead Sulphate is created in the materials of plates during normal discharging, this term is used to describe the generation of a different form (large crystals) of Lead Sulphate, which will not readily convert back to normal material when the battery is charged. Sulfation occurs when a battery is stored too long in a discharged condition, if it is never fully charged, or if electrolyte has become abnormally low due to excessive water loss from overcharging and/or evaporation.


Typically refers to a charge that...

Typically refers to a charge that applies a constant, but small, current to the battery. This is different than a Float charge, though often the term is misused to construe one or the other.

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2 people commented, Tech, Joe
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  • Joe
    I have a old motorcycle 1940, It is 6 volt/ kick start. It calls for a 29 amp battery, I am using 14 amp/ It works fine . Why do I need 29 amps.

    Reply  •  March 23, 2012 at 9:20 am
    • BatteryStuff Tech
      Are you referring to CCA (Cold Cranking Amps) or AH (Amp Hours)? The CCA rating is important for turning the engine over. Since your bike is a kick start, there really is no need for burst power. AH, however, refers to the capacity the battery can supply power for extended period of time. The more AH, the longer you can run your lights and have your radio playing off the battery, for example. If 14 AH is working for you, it‘s because you‘re not drawing on the battery too much. 29 AH, I guess, is what the factory calculated would be good for standard use.

      Reply  •  March 23, 2012 at 12:24 pm