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Battery School

General Battery Care Procedures

General deep cycle battery care procedures

Reasons Why Batteries Fail

General Difference Between Gel and Wet Batteries

State of Charge and Sulfation

Connect Your Batteries for Optimum Efficiency

Just A Little Corrosion Causes Big Voltage Drops

Don't Be Misled By Battery Ratings

Which Deep Cycle Battery Do I Choose?

Daily Amphere-Hour Consumption For Your RV

Safety Tips on Charging Batteries

Determining When A Battery is Fully Charged

Why Are My Batteries Discharged

What is the difference between series battery connections and parallel battery connections and how do they increase battery capacity and voltage?
Answer: In the SERIES CONNECTION, batteries of like voltage and Amp-Hr capacity are connected to increase the Voltage of the battery bank. The positive terminal of the first battery is connected to the negative terminal of the second battery and so on, until the desired voltage is reached. The final Voltage is the sum of all the battery voltages added together while the final Amp-Hr, Cranking Performance and Reserve Capacity remain unchanged.

Battery System: 12 Volt, 225 AH 
Using Two T-105 Deep Cycle Batteries 
(6 Volts, 225 AH each)

Answer: In PARALLEL CONNECTION, batteries of like voltages and capacities are connected to increase the capacity of the battery bank. The positive terminals of all batteries are connected together, or to a common conductor, and all negative terminals are connected in the same manner. The final voltage remains unchanged while the capacity of the bank is the sum of the capacities of the individual batteries of this connection. Amp-Hrs, Cranking Performance and Reserve Capacity increases while Voltage does not.

Battery System: 6 Volt, 450 AH 
Using Two T-105 Deep Cycle Batteries 
(6 Volts, 225 AH each)


COLD CRANKING AMPS (CCA):  The maximum amperes that can be continuously removed from a battery for 30 seconds at zero degrees F before the voltage drops too low to use (7.2 volts).  This term is used only for engine starting batteries, and has little to do with the amp-hour capacity or deep cycle batteries.  This rating will also appear on many deep cycle marine batteries.

CRANKING AMPS (CA):  A rather optimistic market driven rating, especially for “economy” or “value priced” batteries.  The same CCA, but a 32 degrees F (0 C) temperature.  The standard Battery Council International rating is CCA, at 0 degrees F (about -18 C).  The MCA, or Marine Cranking Amps is basically the same at CA.  CCA is about 20% less than CA or MCA.

RESERVE CAPACITY (RC): Reserve capacity is sometime used to rate deep cycle batteries.  It is the number of minutes that a battery can maintain a useful voltage at a constant 25 amp discharge rate at 80 degrees that run heavy loads, although most batteries also have tables that show the AH capacity at different discharge rates.  AH is approximately equal to RC X 0.60)

Jump start procedures

Preparing your batteries for winter

Advantages and Disadvantages of using two 12 volt batteries connected in parallel or two 6 volt batteries connected in series.

Testing the battery