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Battery Maintenance



Visually inspect your battery every two to six months to ensure its life-longevity. Below is a list of factors that directly influence battery performance, and should be checked periodically:
  • Corrosion, dirt and/or oil on the battery case, connectors, and/or posts – Can lead to blockage in the flow of electric current (connectors and posts) or promote resistance (battery case). If dirty or corroded, clean the connectors using a wire brush dipped in a water/baking soda solution (Use one pound of baking soda to one gallon of water). Rinse with water and dry with a clean cloth. A thin coat of battery corrosion inhibitor or petroleum jelly (Vaseline) can be applied to the posts and connectors to help avoid future corrosion.
  • Fluids on or around the battery – This may be an indication that electrolyte is spilling or leaking out. If this is the case, repair or replace the battery immediately.
  • Loose or damaged battery cables and connections - Battery cables should be intact, and the connectors tight at all times. Broken or frayed cables can be extremely dangerous. Replace any cable that appears damaged.
  • Electrolyte level - Check the fluid level in your battery. If necessary, refill with water. Distilled water is most recommended, although any water that is safe to drink (with the exception of mineral waters) is safe to use in a battery. Do not use water with a known high mineral content. Metal impurities in the water will lower the performance ability of the battery. Be cautious not to overfill the battery cells, particularly in warm/hot weather. The natural fluid expansion that occurs with heat will push the electrolyte from the battery.
  • Inactivity - Lack of use can be very harmful to lead-cell batteries. If not using on a regular basis, periodically recharge the battery fully and store it in a cool place. Avoid extremely hot or cold temperatures. If storage time exceeds two months, it may be necessary to fully recharge the battery before re-installing it.


In addition to visual inspection, periodic battery testing is an important preventative procedure. These are common tests used to determine the charge status of your battery:

Open Circuit Voltage (OCV) Test:
  • In order to get an accurate reading of the battery’s charge, remove the battery from the vehicle, or lift the non-grounded lead, so as to turn off all electrical loads. CAUTION: This will cause memory settings, such as clocks, automatic seat adjustments, etc. to be lost.
  • Allow the battery to sit idle for a period of 4-6 hours.
  • Connect a voltmeter to the positive and negative terminals and measure the terminal voltage with no loads or chargers connected to the battery.
  • Compare the OCV reading on the voltmeter with the table below. Please keep in mind that this table assumes a fully charged specific gravity of 1.265.




















  • If the volt reading registers below 75%, the battery needs to be re-charged. If the volt reading is lower than the values shown on the chart, take the battery to a battery specialist for further inspection.

Specific Gravity Test (Wet/Flooded cell batteries with removable vent caps only):

Check the electrolyte level to ensure it is above the top of the plates. If not, add water accordingly and charge before taking readings.

If electrolyte is above the plates, make sure not to add any water to the battery cells to ensure an accurate reading.

Remove the vent caps from the cells.
  • Insert a hydrometer into one of the battery cells and draw liquid into the syringe a few times before pulling out a sample, so that the float reaches the same temperature as the electrolyte. This will increase the accuracy of your reading.
  • Draw enough liquid from the cell such that the hydrometer is full enough to fully support the float.
  • Take a reading, record it, and return the electrolyte to the battery cell.
  • Repeat this procedure with each individual cell.
  • Replace the vent caps and neutralize any liquid that might have spilled using a water/baking soda solution (Use one pound of baking soda to one gallon of water). The solution will fizzle when in the presence of acid. When the fizzing stops, wipe it off with a damp cloth and then dry.
  • Adjust each reading to 80°F. Hydrometers are calibrated at this temperature, so in order to get the accurate gravity measurement, add .004 to each reading for every 10o above 80o F and subtract .004 for every 10o below 80o F.
  • Compare each reading to the chart below. If any fall below 1.155 the battery needs to be recharged. A variation of 0.050 or more between the highest and the lowest cell indicates internal damage in the battery. If such is the case, the battery needs to be replaced. Please keep in mind that this table assumes a fully charged specific gravity of 1.265.














Load Test:

This test is used by professional technician to determine whether a battery needs replacement or not. It consists of a 15-second discharge of the battery at 1/2 the cold cranking amp level. It is a more accurate method than the ones listed above.

  • New batteries should be given a full charge before use.
  • Not recharging a battery after each use causes the battery to sulfate and affects performance and longevity.
  • Avoid charging at temperatures above 120ºF.
  • Do not charge a frozen battery.
  • As batteries age their maintenance requirements change. This could mean longer charging time and/or higher finish rate (higher amperage at the end of the charge). Usually their capacity decreases and they need to be watered more often (if they are vented with removable vents to allow watering).
  • Always use a matched voltage charger and battery pack system. An undersized charger will never get the job done no matter how long you let it run. An oversized charger will cause excess gassing and heat; this situation could cause explosions and/or other damages.
  • Do not overcharge batteries.
  • The alternator is a battery charger. It works well if the battery is not deeply discharged.
  • Deeply discharged batteries can be recharged using these three steps:
1.   Bulk charge – This stage is performed to return 80% percent of the battery energy quickly. Amperage is kept as high as the battery and the charger allow. When the battery voltage reaches approximately 2.41 volts per cell (14.5 volts for a 12-volt battery) absorption charge is initiated.
2.   Absorption charge - current into the battery is limited to hold the terminal voltage at a constant 14.4 V. During this time, the battery is allowed to slowly absorb approximately 20% of the electricity being returned in the charging process.
3.   Float charge: the battery is held at a specified voltage that is well below its gassing point, but high enough that the remaining 5% of capacity can be returned. Typical float voltage for a 12 volt lead acid battery might be 13.1 volts. A battery can be left on float charge for extended periods of time without damage or excessive water loss. However, since there will be some water loss, periodically check electrolyte levels and water when necessary. This type of charge will maintain the battery at 100% readiness and prevent cycling during long term inactivity.


This process should be carried out periodically on wet/flooded batteries ONLY to prevent stratification and sulfation. It consists of running a low-current overcharge after the normal charge cycle has been completed. The extra charge helps keep all cells in balance.

1.   Make sure that you are working with a flooded/wet type of battery.
2.   Remove all current sources from the battery
3.   Connect battery charger (Make sure you are working with a charger that has an equalizing setting)
4.   Set the charger at the proper equalizing voltage.
5.   Start charge.
6.   Batteries will begin to gas and bubble vigorously.
7.   Take gravity readings every hour.
8.   Equalizing is complete when the gravity values no longer rise during the gassing stage.


Sulfation is the formation of lead sulfate crystals on the plates of a lead acid battery that can occur in the following conditions:
  • Battery sits too long between charges. This can mean anywhere from a 24-hour period in extreme hot weather to several days in cooler weather
  • Battery is stored without some type of energy input.
  • Deep cycling a starting battery.
  • Battery is undercharged – even at 90% charge, sulfation can occur with the remaining 10% of battery chemistry not reactivated.

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