When you are boating or traveling with your RV, you want to make sure you have enough electric power to last your trip. Fully charging your deep-cycle (or deep-cell) battery can allow you to running your appliances as you need them. Batteries generate electricity by a chemical reaction of lead and and other elements, so charging safely is also important.
Determine Time Needed
Read the battery label to determine how many amp-hours your deep-cell battery will store. Smaller batteries store 30 to 50 amp-hours. Medium batteries store 55 to 100 amp-hours, and the largest batteries store more than 111 amp-hours.
Find the amp rating on the charger so you know how many amps it can charge. Battery chargers can range from 2 amps to 45 amps.
Use your calculator to divide the battery's amp-hour rating by the charger amp rating and add 10 percent to determine how long it will take you to charge your battery. For example, if your battery has an amp-hour rating of 55 and your charger has an amp-hour rating of 5, and your battery is fully drained, it would take 12 hours (55/5=11 + 1 for the 10 percent) to get it fully charged.
Protect yourself if you have a wet battery (one to which you can add water). Use eye protection to keep you from getting battery acid in your eyes in the unlikely event of an explosion.
Place the battery on a level surface, such as a driveway or sidewalk.
Determine which of the two posts on your battery takes the positive charge and which takes the negative charge. This is indicated by a plus sign near the positive post and a minus sign or dash near the negative post.
Determine which of the alligator clips on the battery charger provides the positive charge and which has the negative charge. Usually the positive clip has red handles and the negative has black handles. But this is not universally true, so make sure to check.
Plug the battery charger into an electric socket close enough to the battery that the cords will all reach.
Attach the positive alligator clip from the battery charger to the positive battery post and the negative alligator clip to the negative post on the battery.
Let the charge continue for the time you calculated.