How To Equalize Charge And Prevent Stratification

Golf courses and businesses that incorporate a fleet of golf cars know that extending the service life of the deep-cycle batteries powering their fleet can significantly lower annual operating costs. But the simple process of regularly recharging batteries with a charger using a constant voltage or a fixed charge algorithm, often leads to a condition called electrolyte stratification. Stratification occurs during discharge and recharge when the acid in the electrolyte fails to mix with the water and settles to the bottom of the battery case. Over time, the concentrated acid at the bottom of the cell can damage the battery plates and significantly reduce the service life of the battery.

View of a severely stratified plate.

To reduce stratification and possibly recover a low-performing battery, you can add an equalization charge at the end of the normal charging process. An equalization charge is simply adding a higher-voltage, extended charge at the end of the normal charging process. Charging the battery at a higher voltage level promotes gassing (bubbling) of the electrolyte. The bubbling “re-mixes” the acid and water and prevents stratification from occurring.

The Equalizing Process
The method used to properly equalize batteries is as easy as using a high-quality battery charger that features an automatic equalizing mode or has the capability to extend or restart the charging process as needed. Because the process causes the electrolyte to gas, make sure you perform it in a well ventilated area and wear personal protective equipment including safety glasses and gloves. Follow these procedures to properly equalize your batteries.

1.       Make sure the battery is a flooded Lead-Acid type.

2.       All electrical loads to the battery must be removed.

3.       Connect your charger and charge the batteries until the normal charge
cycle is completed.

a.) If the charger is equipped with an automatic equalizing mode, make sure the charger is
connected and powered up long enough to complete the equalization.

b.) If the charger is not equipped with an automatic equalization mode, assure the charger
completes a full, automatic charge and then restart the charger by disconnecting AC
power and reconnecting. The charger should restart and extend the charge time by 1-3

4.       Correct equalizing will cause gassing and bubbling of the electrolyte.

5.       Take specific gravity readings every hour.

6.       You will know that the equalization process is complete when the specific gravity values no
longer increase during the gassing stage.  If the charger terminates the charge automatically
before the hourly specific gravity readings are constant, restart the charger and continue the
process until specific gravity readings are constant.

7.       Make sure to replace any water lost during the process.

Equalizing is just one of several procedures you should be adding to your maintenance schedule every time you service the batteries.  This regular service, including watering, should be performed at least once a month, or more frequently during periods of heavy use. For more information, contact U.S. Battery Manufacturing, 1675 Sampson Ave. Corona, CA 92879. (800) 695-0945. Visit

New Carbon Additives May Not Be The Best Answer For Battery Sulfation Issues In Renewable Energy Applications

There’s been some talk recently about the use of carbon additives to reduce the effects of sulfation in renewable energy batteries. Sulfation can occur when batteries are operated in a partial state of charge (PSOC) application, common when batteries are charged with solar cells, wind turbines and other unpredictable power sources.  Even though these systems regularly recharge the batteries, they don’t always provide a sufficient level of overcharge. The effect of continual undercharge can, over time, cause “hard sulfate” crystals to form on both the positive and negative battery plates.  These crystals can reduce the capacity of the battery and make it even more difficult to fully charge, resulting in short battery life.

Sulfation related to PSOC applications is a phenomenon that was first observed in electric vehicle and hybrid electric vehicle applications using sealed valve regulated lead acid batteries (VRLA).  When AGM (or GEL) VRLA batteries are used in PSOC applications, the recombination process occurring at the negative plate disproportionately discharges the negatives in relation to the positives and creates an imbalance in their relative states of charge.  Normally this imbalance is corrected by providing enough overcharge during normal charge, and/or providing an equalization charge, to bring them back into balance.  In PSOC applications, the batteries are not overcharged or equalized enough to re-balance the state of charge, and the negative plates become severely sulfated.

Several battery research groups have found that by using various new types of carbon in the negative plates of VRLA batteries, the sulfation issue could be addressed.  “These new carbons are often referred to as smart carbon, hyper carbon, ultra carbon, graphene or nano-carbon,” says Fred Wehmeyer, Senior VP Engineering at U.S. Battery Manufacturing. “But they may or may not be composed of carbon nano-tubes that are still too expensive for large scale applications.”

The significance of this is that negative plate sulfation is a phenomenon that applies specifically to VRLA (AGM & GEL) batteries.  Smart carbon technologies intended to address negative plate sulfation in VRLA batteries do nothing to address sulfation of the positive plates in a flooded deep cycle battery, which is the primary issue when these batteries are undercharged or used in PSOC applications.
U.S. Battery has developed a different approach to address sulfation using the company’s exclusive Outside Positive (OSP™) plate battery design.  The OSP™ plate construction is designed to balance the capacity of the positive plates versus the negative plates.

This balanced active material ratio allows the positive and negative plates to reach full charge at the same time, thus preventing sulfation of one plate versus the other.  Most batteries with conventional OSN (outside negative) plate construction end up with an excess of negative active material.  Adding “Smart Carbon” to the negatives does not address this active material imbalance problem.  Balancing the active materials with OSP™ addresses the disparate sulfation problem in addition to the other benefits.

“The battery industry is continually looking for ways to improve the current technology. Sometimes the latest and greatest idea isn’t always the best for every application,” says Don Wallace CMO Executive Vice President at U.S. Battery Manufacturing. “At the end of the day, you often find that new versions of old ideas are the most productive. Either way involves exhaustive testing to prove or disprove, and in the end, it will ultimately be the customer who makes the determination. It is our job to do the background work necessary to provide customers with the necessary data and quantifiable analysis so that they can make the most educated buying decision. This recent news about carbon has been touted as something that can drastically improve the overall performance of the flooded lead acid battery. But the facts should be completely understood before buying flooded batteries with a carbon additive when sold as a value added feature.”
For additional information on U.S. Battery’s OSP™ battery design for Renewable Energy applications, visit