Selecting a battery for your RV can be confusing. Do you need a battery to start the engine or a deep cycle battery to operate the furnace, lights, water pump, and other appliances in the RV. Next we need to know whether we will use a flooded cell battery, an oil filled battery, a gel cell battery, or an absorbed glass mat battery.

In general engine starting batteries have many thin plates separated by fibreglass sheets, to prevent the plates from touching, immersed in electrolyte ( a combination of 36% sulfuric acid and 64% water) that will supply up to 300-amperes of current to the starting motor for a short period of time. Most engines start within 30 seconds. As soon as the engine starts, the battery begins to recharge from the alternator and the battery is not used as long as the engine keeps operating.

A deep cycle battery is made from plates that have a thicker layer of chemicals coating their surface. These batteries allow smaller currents to be drawn for a long period of time. This is especially necessary when the weather is cold and the furnace needs to run all night long.

Flooded cell batteries have two sets of lead plates coated with chemicals completely immersed in a liquid electrolyte. The larger the total surface area of the plates that are covered by the electrolyte, the longer the battery can supply current. As the battery is used over a period of time, or during recharging, the water in the electrolyte evaporates, the electrolyte level falls below the top of the plates, the plates dry out and the battery becomes sulfated or impossible to recharge. Therefore the level of electrolyte needs to be check on a regular basis and replenished only with distilled water when necessary. Since these batteries give off hydrogen gas and water vapour, the top of the battery needs to be cleaned often to prevent electrical charge from leaking from one terminal to the other across the top surface of the battery. These gases also cause corrosion at the terminals on the top of the battery. Flooded cell batteries are popular because of their lower price and the fact that they are available almost anywhere in North America when you need a replacement. (Top)

Deep cycle batteries with an oil layer on top of the electrolyte were introduced in the Arctic to operate equipment on the Distant Early Warning Line in a hostile cold weather environment. These batteries did not allow the hydrogen gas that is produced during normal use to escape, or allow the electrolyte level to fall below the plates. As a result, the batteries had a long lifetime, and were able to hold a charge for many months until the battery was needed to start up a generator. These batteries have been very successful as deep cycle house batteries in Rvs and for wheelchairs. If a battery was to give off corrosive gases in a wheelchair environment, it would not be good for the wheelchair rider.

Gel cell batteries were originally designed for use in boats and portable equipment where the batteries are subjected to heavy vibration and the possibility of being operated in a non-vertical position where ordinary liquid electrolyte might spill out. The electrolyte in the gel cell is suspended in a gelatin type material so that it will not spill even if the battery is operated upside down. Gel cells are often called recombinant batteries because oxygen gas given off at the positive plate is recombined with hydrogen given off at the negative plates to keep the electrolyte moist. If the cell is not kept under constant pressure inside the casing this effect will not take place. Not all the hydrogen created during overcharging is recombined and can build up pressure inside sufficient to open the vents. When this happens, the hydrogen vents to the outside air with the possibilities of an explosion if an ignition source is available at this time. A special regulator is needed to prevent the gel cell battery from being damaged by the high voltages necessary to recharge flooded cell batteries. The use of temperature compensation during charging is recommended. The benefit of the gel cell battery is that it recharges in a short time, but the reserve capacity is normally lower than that of a flooded cell.

Absorbed Glass Mat batteries have a highly porous micro fibre sponge-like glass mat between the plates to absorb the electrolyte and have no free liquid. Similar to gel cells they are sealed, use positive pressure to allow recombinant gas effects, so they do not lose liquid during use or recharging. AGM batteries offer twice the expected life cycles as a gel cell and can withstand higher voltages during charging. If the charging voltage is too high then the life of any battery may suffer. You need to check with your battery supplier to be sure that the charging voltage of your RV is not too high for proper charging. If the voltage is too low, then the battery will not charge completely. Many AGM batteries are built with a spiral plate construction so that more area of the plate is available for connecting the electrodes which lowers the internal resistance of the battery. (Top)

Lifeline batteries built by Concorde Battery Corporation are the first batteries delivered to the US Air force for use in Stealth bombers, F-18 fighter jets, and other demanding military applications. They are the most advanced RV batteries manufactured and are subject to the same stringent standards demanded by FAA and Military specifications. Since AGM batteries do not gas or leak electrolyte they are maintenance free, can be mounted in any position, do not need to be vented like conventional batteries, and can be charged at higher currents than other types.

Deep cycle batteries are not suitable for engine starting as they are not designed to supply large currents for short times. Many motorhomers are replacing their two 12-volt deep cycle batteries with two 6-volt golf cart batteries that have greater reserve capacity and still provide 12-volts when connected in series with each other. They are slightly taller than a group 27 battery but will fit in most battery compartments. They are more cost efficient because they can withstand more charging cycles. When one goes bad when you are on a trip, you need to replace both of them. They may not be as easily found when you are away from the cities.

Always install the largest capacity batteries that will fit in your battery compartment. You can never have too much capacity. Bigger batteries may only be depleted by 25% of their total capacity where a smaller battery that loses the same amount of charge will be down by as much as 40%. Batteries will last longer if they donŐt have to spend as much time on the recharger.

Lifeline batteries are available from dealers in your area and distributed in Canada by Mobile Power Solutions For more information, call (877)841-3770 or www.lifelinebatteries.com (Top)