All sealed lead acid batteries self-discharge. If the capacity loss due to self-discharge is not compensated for by recharging, the battery capacity may become unrecoverable. Temperature also plays a role in determining the shelf life of a battery. Batteries are best stored at 20℃. When batteries are stored in areas where the ambient temperature varies, self-discharge can be greatly increased. Check the batteries every three months or so and charge if necessary.

Sealed lead acid battery life is determined by many factors. These include temperature, depth and rate of discharge, and the number of charges and discharges(called cycles).
What is the difference between float and cycle applications.?

A float application requires the battery to be on constant charge with an occasional discharge. Cycle applications charge and discharge the battery on a regular basis.

Valve-regulated sealed maintenance-free lead-acid battery is different with other batteries. In fact, though less evaporation of the electrolyte and no leakage, the battery still needs a little bit maintenance work. Because the charging equipment do not reach the ideal level yet, it is inevitable that there are small amount of evaporation of distilled water. For those who know a little about the battery knowledge, if find the capacity decreased above, they could add some water in moderation to recover the concentration of electrolyte. A little bit lower concentration is also okay. Those activities are good for the plates.

During the battery charging process, electrical energy transforms into chemical energy, heat energy and other energy. It is normal phenomenon for that battery is heating during charging. But at high temperature, battery should be timely check whether charge current is too excessive or internal short circuit happen and so on. And, if there are less electrolyte, the internal resistance will increase, which also can cause the high temperature and high voltage when battery is charging. Aging battery, dry electrolyte, internal short circuit, etc. will cause heating as well. If charging equipment can’t keep invariable at the later charging period, the voltage value will exceed permission value, and the temperature will raise at the same time. Finally, the battery will be bulged seriously and at the end of its life.

Try not to mean or upend the battery which is in use, for avoiding that lots of gas produced in the battery can’t exhaust from the valve smoothly, especially don’t do it when charging, or this activity will cause cover bombing.

The battery in the charging and discharging process, will release certain heat. But a lot of  heats is very harmful to the battery. Heating will make electrolyte water evaporation and dried up at first, and then gradually reduce the charging efficiency, deform plate, increase resistance, make the mechanical components oxidation, burn out plates or clapboard, finally reducing battery capacity and shortening battery life.

Routine battery examinations detects irregularities in the charging system as well as in the batteries. The principle method is to examine the electrochemistry of the battery through hydrometric electrolyte inspection. As previously discussed, this important examination cannot be accomplished with sealed absorption or gel batteries. Voltage readings alone require experience to interpret. Hydrometric readings will uncover early warnings of overcharging or over discharging before batteries are damaged. The state-of-charge and reliability of a lead acid battery can best be determined by the specific gravity of the electrolyte measured directly with a common bulb-type hydrometer with a glass float. We do not recommend the ball float type hydrometer. Specific gravity is a unit of measurement for determining the sulfuric acid content of the electrolyte. The recommended fully charged specific gravity of marine batteries is 1.255 to 1.265 taken at 80ĄăC More than .025 spread in readings between fully charged cells indicates that the battery may need an equalization charge. If this condition persists, the cell is failing and the battery should be replaced. Since water has a value of 1.000, electrolyte with a specific gravity of 1.260 means it is 1.260 times heavier than pure water while pure concentrated sulfuric acid has a specific gravity of 1.835.

Though there is a strict battery selection procedure, after a certain period usage, the non-homogeneity will appear more and more obviously. Meanwhile, charging equipment can’t choose and recongnize the weak battery out, so it is user who can take control of how to keep the equilibrium of battery capacity. User would better test the OCV of every battery regularly or irregularly in the middle and later period of battery pack usage and recharge the battery of lower voltage separately, in order to make the voltage and capacity as the same as other batteries ,  that decrease the difference between the batteries.

OVERDISCHARGING is a problem which originates from insufficient battery capacity causing the batteries to be overworked. Discharges deeper than 50% (in reality well below 12.0 Volts or 1.200 Specific Gravity) significantly shorten the Cycle Life of a battery without increasing the usable depth of cycle. Infrequent or inadequate recharging can also cause over discharging symptoms called SULFATION. Despite that charging equipment is regulating back properly, over discharging symptoms are displayed as loss of battery capacity and lower than normal specific gravity. Sulfate occurs when sulfur from the electrolyte combines with the lead on the plates and forms lead-sulfate. Once this condition becomes occurs, marine battery chargers will not remove the hardened sulfate. Sulfate can usually be removed by a proper desulfation or equalization charge with external manual battery chargers. To accomplish this task, the flooded plate batteries must be charged at 6 to 10 amps. at 2.4 to 2.5 volts per cell until all cells are gassing freely and their specific gravity returns to their full charge concentration. Sealed AGM batteries should be brought to 2.35 volts per cell and then discharged to 1.75 volts per cell and then this process must be repeated until the capacity returns to the battery. Gel batteries may not recover. In most cases, the battery may be returned to complete its service life.

CHARGING Alternators and float battery chargers including regulated photo voltaic chargers have automatic controls which taper the charge rate as the batteries come up in charge. It should be noted that a decrease to a few amperes while charging does not mean that the batteries have been fully charged. Battery chargers are of three types. There is the manual type, the trickle type, and the automatic switcher type.

Discharge efficiency refers to the ratio of actual power to nominal capacity when battery discharges at the ending voltage in certain discharge conditions. It is mainly affected by factors such as discharge rate, environmental temperature, internal resistance. Generally, the higher the rate of discharge is, the lower the discharge efficiency will be; the lower the temperature is, the lower the discharge efficiency will be.

One cycle of a battery is a discharge from full charge to full discharge and a return to full charge again. The total number of cycles a battery can perform before failure is called its Cycle Life. Moat battery manufacturers will not discus the Cycle Life of their product. Many advertised Deep Cycle batteries have not been tested, or, which is the case with cranking batteries, were never designed for long Cycle Life .