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.

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.

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.

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.

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.

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.