14.1. Storing a battery on a concrete floor will discharge them.

All lead-acid batteries will naturally self-discharge which can result in loss of capacity from sulfation. The rate of self-discharge is most influenced by the temperature of the battery'* electrolyte and the chemistry of the plates. This self-discharge is often mistaken for concrete floor causing the battery to drain. Some experts believe that storing car or deep cycle batteries on a colder concrete floor might actually slow down the self-discharge (leakage) rate because the floor acts as a heat sink and cools the battery. (Please see Section 13 for more information on storing batteries and Section 1 for more information on sulfation.

In the early 1900s, when battery cases were made of porous materials such as tar-lined wood boxes, storing batteries on concrete floor would accelerate their natural self-discharge due to external leakage. Modern battery cases are made of polypropylene or hard rubber. These cases are sealed better, so external leakage-causing discharge is no longer a problem, provided the top of the battery is clean and free from wet or dried electrolyte and the same temperature as the floor.

Large differences in temperature could cause electrolyte stratification within very large batteries (>250 AH) which could accelerate it'* internal "leakage" or self-discharge if the battery is sitting on an extremely cold concrete, stone or steel floor in a warm room, boat or submarine. Stirrers or bubblers are often used on these types of large batteries to keep the electrolyte from stratifying. Undercharging will also cause electrolyte stratification, which can also result in loss of capacity from sulfation.

While a battery is in storage or not being used, the discharge is a result of parasitic load or natural self-discharge. Parasitic load is the constant electrical load present on a battery while it is installed in a vehicle even when the ignition key is turned off. The load is from the continuous operation of electrical appliances, such as an emissions computer, clock, security system, maintenance of radio station presets, etc. While disconnecting the negative battery cable will eliminate the parasitic load, it has no affect on the natural self-discharge of battery. Thus, permanent sulfation can be a huge problem for lead-acid batteries while sitting for long periods on a dealer'* shelf, in a basement, cellar, barn or garage, or in a parked vehicle, especially in hot temperatures.