How to Know When a Sealed Gel Cell Lead Acid Battery Is Charged

A sealed gel cell battery differs from the conventional wet cell battery in that its electrolytes cannot be replaced or refilled. Rather, as its name suggests, the gel cell battery is permanently sealed, while the electrolytes are suspended using a thickening agent such as silica. Thus, if the battery’s shell is breached, it will not leak. However, if you own a gel cell battery, you must take special care when recharging it. A special battery charger is needed, preferably one with voltage protection and a variable amp rate. 

 

Purchase a digital 12-volt voltmeter at most any automotive supply store. This instrument will give you an accurate reading of the battery’s voltage, and thus tell you when it has been fully charged. Depending on the exact type of voltmeter, it is generally inexpensive, often costing less than $40.

 

Charge your sealed gel cell battery slowly. Again, a battery charger specifically designed for sealed gel cell batteries should be used. If you do not have such a charger, try using one that has voltage protection, meaning it shuts off when the battery is completely charged, and a setting that allows you to adjust the amp rate. Charging the battery at two amps should suffice, though the exact time needed to achieve a full charge will depend on how severely depleted the battery is.

 

Turn off the charger, if you haven't already done so, and attach the positive clamp or probe of the voltmeter to the positive terminal/post on the gel cell battery. Then connect the negative clamp or probe to the negative terminal/post. Make sure the voltmeter has a good connection with the battery, otherwise your reading may be inaccurate.

 

Read the digital display on the voltmeter. You should see a reading of approximately 12.8 or 12.9 volts when the gel cell battery is fully charged. With a reading less than 12.8, you may continue charging. However, if you get a reading above 12.9 volts, stop charging the battery immediately. Overcharging a gel cell battery can permanently damage it, even to the point where it’s no longer functional.

 

Check the battery frequently if you must continue charging and stop as soon as you hit 12.8 volts on your voltmeter.