Lead-acid gel batteries are considered safer than regular fluid-filled lead-acid batteries. Each battery cell contains a thick gel, if the battery gets dropped or damaged and the case splits open, the gel remains in place, whereas a fluid-filled battery would leak dangerous sulfuric acid. Lead-acid gel batteries are sealed units, you can't access the cells and replenish the electrolyte. It also means they need to be charged and discharged differently from a regular lead-acid battery. If you find you have trouble getting your battery charged properly, try a refurbishment process to repair it.
Use whatever energy is left in the lead-acid gel battery. This process helps refurbish the cell structure. If there's not enough energy to power equipment requiring a lot of energy, turn on lights. Leave the battery to discharge until the lights are very dim.
Place your battery charger near your lead-acid gel battery. Check your battery charger for a low charge setting such as "trickle charge." Some battery chargers have a setting for "Gel." It's important the battery receive a slow charge as charging it fast will damage the battery beyond repair. If your battery charger doesn't have a slow charge rate, obtain or borrow a charger that does.
Select the lowest charge setting on the battery charger. Use "Gel" if it has the setting. Connect the two battery cables attached to the charger to the lead-acid gel battery terminals. Use the clamp on the end of the red cable and attach it to the positive "+" terminal of the battery. Use the clamp on the end of the black cable and attach it to the negative "-" terminal of the battery.
Turn on your battery charger to begin charging the lead-acid gel battery. The slow charge rate on a totally discharged gel battery allows the cell structures to repair themselves. Leave it for five to six hours and then touch the side of the battery with your hand. If it is charging correctly, the battery is getting warm. Leave it for another five or six hours then touch the battery again and you should find it is warmer, but not hot. If it is hot, turn off the charger immediately and let the battery completely cool before restarting the charge.
Turn off the charger after a total of 12 hours. Don't leave it too much longer, as unlike regular lead-acid batteries you can overcharge a gel battery. Disconnect the battery charger cables.
Use your lead-acid gel battery in the usual way and it should hold a full charge. Repeat the steps at least once or twice a year to prolong the life of a lead-acid gel battery.
