DIFFLOCK.com - Buyer's Guide

Standard Car Battery Frequently Asked Questions (FAQ)

This FAQ assumes 12-volt, six cell, negative grounded, lead-acid SLI batteries used to start petrol or diesel engines found in most cars, 4x4s, light trucks, vans and caravans. The information contained within the FAQ would also apply to starting batteries found in trunks, motorcycles, boats, snowmobiles, jet skis, farm tractors, lawn and garden tractors, SUVs, etc. Aircraft, busses and larger vehicles use higher volt systems. Some aircraft use special purpose AGM and Ni-Cad batteries for starting because of the extreme cold. For 6-volt batteries, divide the voltage by two; for 8-volt batteries, divide by 1.5; for 24-volt batteries, double the voltage; and for 36-volt batteries, triple the voltage. The technical stuff is in italics

Deep Cycle Battery Frequently Asked Questions (FAQ)

This FAQ assumes a 12-volt, six cell, negative grounded, deep cycle lead-acid batteries found in most recreational and deep cycling applications. The information contained within the FAQ would also apply to deep cycle batteries used in motive, traction, stand-by and float applications. For six-volt batteries, divide the voltage by two; for eight-volt batteries, divide by 1.5; for 24-volt batteries, double the voltage; for 36-volt batteries, triple the voltage; and for 48-volt batteries, multiple by four. The technical stuff is in italics

Storing Car, Motorcycle, Deep Cycle and Other Lead-acid Batteries

Why bother?

Deep cycle and other lead-acid batteries are perishable. During the discharge process, soft lead sulfate crystals are formed in the pores and on the surfaces of the positive and negative plates inside a lead-acid battery. When a battery is left in a discharged condition, is continually undercharged, or the electrolyte level is below the top of the plates, some of the soft lead sulfate re-crystallizes into hard lead sulfate. It cannot be reconverted during subsequent recharging. This creation of hard crystals is commonly called "lead sulfation". It the leading cause and accounts for over 80% of the deep cycle lead-acid battery failures. The longer sulfation occurs, the larger and harder the lead sulfate crystals become. The positive plates will be light brown and the negative plates will be dull, off white. These crystals lessen a battery's capacity and ability to be recharged. This is because deep cycle batteries are typically used for short periods and then are stored the rest of the year while they are slowly discharging. In contrast, a starting battery is normally used several times a month, so sulfation rarely becomes a problem unless it is storged for over two weeks.

Sulfation is a result of lead-acid battery discharge while in storage, which is a consequence of parasitic load and natural self-discharge. Parasitic load is the constant electrical load present on a battery while it is installed in a vehicle even when the power is turned off. The load is from the continuous operation of electrical appliances, such as an emmisions 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 other problem, the natural self-discharge of battery. Thus, sulfation can be a huge problem for lead-acid batteries while sitting on a dealer's shelf, in a basement, or in a parked vehicle, especially in hot temperatures.

How do I prevent sulfation?

The best way to prevent sulfation is to keep a lead-acid battery fully charged because lead sulfate is not formed. This can be accomplished three ways. Based of the battery type you are using, the best solution is to use a charger that is capable of delivering a continuous "float" charge at the battery manufacturer's recommended float or maintenance voltage for a fully charged battery. 12-volt batteries, depending on the battery type, usually have fixed float voltages between 13.2 VDC and 13.6 VDC, measured at 70° F (21.1° C) with an accurate (.5% or better) digital voltmeter. For a six-volt battery, measured voltages are one half of a 12-volt battery. This can best be accomplished by continuously using a three stage or four stage, microprocessor controlled charger, such as a Battery Tender (Deltran), Truecharge (Statpower), BatteryMinder, Schumacher, etc., or by voltage-regulated charger, such as a ChargeTek, etc., set at the correct float voltage. By contrast, a cheap, unregulated "trickle" or a two stage manual charger can overcharge a battery and destroy it.

A second and less desirable method is to periodically recharge the battery when the State-of-Charge drops to 80% or below. At 70° F (21.1° C), a battery with 100% State-of-Charge measures approximately 1.261 Specific Gravity or 12.63 VDC and 80% State-of-Charge measures 1.229 Specific Gravity or 12.47 VDC. Maintaining a high State-of-Charge tends to prevent irreversible sulfation. The recharge frequency is dependent on the parasitic load, temperature, a battery's condition, and plate formulation (battery type). Temperature matters! Lower temperatures slow down electrochemical reactions and higher temperatures speed them up. A battery stored at 95° F (35° C) will self-discharge twice as fast than one stored at 75° F (23.9° C).

A third technique is to use a voltage regulated solar panel or wind generator designed to float charge batteries. This is a popular solution when AC power is unavailable for charging.

So how do I store my battery?

There are four simple steps. First, if the battery has filler caps, check the electrolyte (battery acid) level in each cell. If required, add only distilled water to the recommended level, but do not overfill and clean the top of the battery and posts. Second, fully charge the battery. Third, store the battery in a cool (above freezing), dry place where it can be easily recharged. Finally and most importantly, prevent sulfation by keeping the battery charged at 100% State-of-Charge level by continuously float charging or by frequently recharging the battery.

CAR & DEEP CYCLE BATTERY INFORMATION