Periods of inactivity can be extremely harmful to lead-acid batteries. When placing a battery into storage, follow the manufacturer’s recommendations and/or the recommendations below to ensure that the battery remains healthy and ready for use. The most important things to avoid:
- Avoid locations where freezing temperatures are expected. Keeping batteries at a high state of charge will also prevent freezing. Freezing results in irreparable damage to battery plates and containers. NOTE that if a battery is kept completely charged, the chances of freezing are minimal.
- Avoid direct exposure to heat sources, such as radiators or space heaters. Temperatures above 80ºF / 26ºC accelerate the battery’s self-discharge characteristics. NOTE that heat causes more damage to a battery than cold ever will so keep your battery storage area as cool as possible.
- NOTE that storing your battery on concrete will not damage your battery!
Step-by-step storage procedure
- Completely charge the battery before
- Store the battery in a cool, dry location, protected from the
- During storage, monitor the specific gravity (flooded) or voltage. Batteries in storage should be given a boost charge when they show a charge of less than 75% or approximately 12.40 volts for a 12-volt battery. See the “Open Circuit Voltage” table
- Completely charge the battery before re-activating.
- For optimum performance, equalize the batteries (flooded) before putting them back into service. Refer to the Equalizing section for this procedure.
WARNING – DO NOT EQUALIZE CHARGE GELL OR AGM BATTERIES! Equalizing is an “over voltage-over charge” performed on flooded lead-acid batteries after they have been fully charged to help eliminate acid stratification. It helps to eliminate the acid stratification and sulfation that happens in all flooded lead acid batteries. Acid Stratification is the #1 killer of flooded lead acid batteries.
Laboratory-designed, specific to Discover, “Balance” charge algorithms have been designed and are included in all Discover recommended Industrial Commercial charges offered for sale wherever our Discover AGM and GELL VRLA DRY CELL products are sold. Visually the Balance Charging curve diagram is similar to a flooded equalize charge curve in its finishing voltage. Still, it is strictly controlled to promote proper active material conversion and not to promote gassing or bubbling of the acid to help reduce acid stratification, as in a flooded battery. Discover’s Balance charging algorithms are HIGHLY recommended for batteries being installed in strings, larger batteries using taller plate groups and/or with batteries constantly being subjected to high-rate deep-cycle.
Battery Council International BCIS-04 Rev. Draft Dec02 3.8.2 states that for Flooded batteries, “An equalizing charge is allowed in conjunction with constant voltage charging to promote electrolyte mixing and to ensure complete recharge. The equalizing charge must not exceed 3 hours and should be used cautiously to avoid excessive overcharge. For VRLA DRY CELL batteries, no equalizing charge should be used unless specifically recommended by the manufacturer.”
Batteries seem to attract dust, dirt, and grime. Keeping them clean will help you spot trouble signs if they appear and avoid associated problems.
- Check that all vent caps are tightly in place (flooded batteries).
- Clean the battery top with a cloth or brush and a solution of baking soda and water.
- When cleaning, do not allow any cleaning solution or other foreign matter to get inside the battery (flooded batteries).
- Rinse with water and dry with a clean cloth.
- Clean battery terminals and the inside of cable clamps using a post and clamp cleaner.
- Clean terminals will have a bright metallic shine.
- Reconnect the clamps to the terminals and thinly coat them with petroleum jelly (Vaseline) to prevent corrosion.
- Keep the area around the batteries clean and dry.
Flooded batteries need water. More importantly, watering must be done at the right time and in the right amount or the battery’s performance and longevity suffers. Water should always be added after fully charging the battery. Before charging, there should be enough water to cover the plates. If the battery has been discharged (partially or fully), the water level should also be above the plates. Keeping the water at the correct level after a full charge will prevent having to worry about the water level at a different state of charge. Depending on the local climate, charging methods, application, etc., it is recommended that batteries be checked a minimum of once a month and/or once every seven discharge–charge cycles until you get a feel for how thirsty your batteries are. Important things to remember:
- Do not let the plates get exposed to air. This will damage (corrode) the plates.
- Do not fill the water level in the filling well to the cap. This will likely cause the battery to overflow with acid, consequently losing capacity and causing a corrosive mess.
- Do not use water with high mineral content. Use distilled or de-ionized water only.
CAUTION: The electrolyte is a solution of acid and water, so skin contact should be avoided.
Step-by-step watering procedure: (Flooded batteries only)
- Open the vent caps and look inside the fill wells.
- Check the electrolyte level; the minimum level is at the top of the plates.
- If necessary, add just enough water to cover the plates at this time.
- Put batteries on a complete charge before adding additional water (refer to the Charging section).
- Once charging is completed, open the vent caps and look inside the fill wells.
- Add water until the electrolyte level is 1/8" below the bottom of the fill wells.
- A piece of rubber can be used safely as a dipstick to help determine this level.
- Clean, replace, and tighten all vent caps.
WARNING: Never add acid to a battery.
Use this same procedure for VRLA DRY CELL batteries and Flooded batteries:
- Recharge if the open circuit voltage is below 75%.
- If you have an adjustable load tester, set the load at 3 to 3.5 times the 20-hour rate.
- Apply the load for 15 seconds. The voltage should stabilize above 9.6 volts while on load.
- If the battery has a CCA rating, you can apply a load equal to ½ the rating for 15 seconds. The voltage should stabilize above 9.6 volts while on load.
- To apply a more determined test, you may apply a load equal to 100% of the rated CCA or 5 to 6 times the 20-hour rate for 30 seconds. The voltage should stabilize above 7.2 volts while on
- If below 9.6 volts (7.2 volts for the 100% CCA test), recharge and repeat the test. If below 9.6 volts (7.2 volts for the 100% CCA test) again, replace the battery.
For accurate voltage readings, batteries must remain idle (no charging, no discharging) for at least 8 hours, preferably 24 hrs.
- Disconnect all loads from the
- Test specific gravity if possible. The OCV of the tested cell will be the specific gravity reading + .84
- Example 1.22 s.g. + .84 = 2.06V
- Measure the voltage using a DC voltmeter.
- Check the state of charge with the Table below.
- Charge the battery if it registers 0% to 75 % charged.
After a charge, if the battery registers below the Temperature Compensated values illustrated in “How can you tell if a battery is fully charged” or “How can I measure my battery's State of Charge,” the following conditions may exist:
- The battery was left in a state of discharge for too long.
- The battery has a bad cell.
Batteries in these conditions should be taken to a specialist for further evaluation or retired from service.