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Phone: 503-362-2684
Fax: 503-362-2787

2725 Portland Rd. NE,
Salem, OR 97301


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

To ensure proper testing of batteries and to avoid premature battery replacement, the consumer should be aware of some critical information based upon the "state of charge". Nationally, between 30% to 50% of all batteries picked up as "junk" batteries are actually good, useable batteries (taken from Battery Council International source). There are many reasons for this alarming statistic but as a consumer, if you know some "rules" about battery testing and battery state of charge, you’ll be informed and will avoid the pitfalls that many fall unto.

Below is a very important table which compares battery "state of charge", "specific gravity" and "voltage". The line passing through the "75%", "1.225", and "12.40" represents important information for the consumer. If your battery has a measured specific gravity of less than 1.225 and a voltage less than 12.4, it usually will fail the prescribed "load test" that battery specialists use as their most important diagnostic test. As a consumer, if the battery does not have a "dead cell", you should insist that it be charged to a level above 1.225 specific gravity (where it can be measured) and then tested before purchasing a new battery. We recommend that you focus on specific gravity (for serviceable batteries) as this measurement provides a more accurate reading of state of charge than open circuit voltage. Accurate voltage readings require that the battery sit up to 2 hours before measurements can be made. Why buy a new battery just to simply replace a discharged one?

For those of you who store your batteries or let them sit without use, be aware that a process called "sulfation" occurs if the battery’s specific gravity falls below 1.225 or below 12.4 volts. Sulfation is actually a hardening of the battery’s internal plates which need to remain soft and porous so that acid can flow through them. If the flow of acid is reduced, the battery performance is greatly reduced regardless of how much you attempt to charge the battery. Monitoring your batteries for these parameters, particularly specific gravity as it changes less rapidly than voltage, will ensure you get maximum life from them.

100%   1.265   12.62(6.3)
90%   1.251   12.54
80%   1.236   12.45
75%   1.225   12.40(6.2)
60%   1.206   12.27
50%   1.190   12.18
25%   1.155   11.97(6.0)
DISCHARGED   1.120   11.76

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?

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