Watch for liquid on the battery or in the battery box. This could indicate a charger, maintenance or battery problem, which could require immediate attention. Pay attention to the length of time it takes to charge batteries. A variation may indicate a potential problem. Since you must recharge your batteries regularly it is important to use the correct charger with your batteries.
Some chargers have the capability of charging both lead acid and gel cell batteries.
There should be a clearly marked switching device on the charger. Just make sure it's switched to the right position for your batteries. If you are a traveler and plan on visiting a foreign country, plan ahead. Find out what the voltage is there. In the United States the standard voltage is 110 volts.