Sealed batteries are known as maintenance free batteries. They are made with vents that (usually) cannot be removed. A standard auto or marine maintenance free battery is sealed, but not fully leak proof. Sealed batteries are not totally sealed since all batteries must allow gas to vent during charging. There are sealed lead acid (SLA) batteries that are non-spillable. Please information on our SLA batteries, see AGM and Gel batteries below.

The newer type of sealed nonspillable maintenance free valve regulated battery uses 'Absorbed Glass Mats' as separators between the plates. This is a very fine fiber Boron-Silicate glass mat. AMG batteries is very popular in stand by applications such as UPS,EPS.

The advantages of AGM batteries are no maintenance, sealed and non-spilling. AGM batteries are 'recombinant' – which means the Oxygen and Hydrogen recombine inside the battery. These use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost. Since the internal resistance is extremely low and very compact construction, there is very good high rate performance and energy density, also can be faster recharge. AGM batteries have a very low self-discharge rate (from 1% to 3% per month). So they can sit in storage for much longer periods without charging. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.

A gel battery design is typically a modification of the traditional flooded lead acid battery. A gelling agent is added to the electrolyte to reduce movement inside the battery case to make the electrolyte as a immobilized state. Many gel batteries also use one way valves in place of open vents, this helps the normal internal gasses to recombine back into water in the battery like a AGM battery, reducing gassing. 'Gel ' batteries also are non-spillable like a AGM battery. Gel battery must be charged at a lower voltage (C/20) than flooded or AGM to prevent excess gas/heat from damaging the cells.

The reserve capacity of a battery is defined as the number of minutes that it can support a 25 ampere load at 80°F until its terminal voltage drops to 1.75 volts per cell or 10.50 volts for a 12V battery. Thus a 12V battery that has a reserve capacity rating of 100 signifies that it can be discharged at 25 amps for 100 minutes at 80°F before its voltage drops to 10.75 volts.

The cold cranking ampere (CCA) rating refers to the number of amperes a battery can support for 30 seconds at a temperature of 0°F until the battery voltage drops to 1.20 volts per cell, or 7.20 volts for a 12V battery. Thus, a 12V battery that carries a rating of 600 CCA tells us that the battery will provide 600 amperes for 30 seconds at 0°F before the voltage falls to 7.20V.

The marine cranking ampere (MCA) rating refers to the number of amperes a battery can support for 30 seconds at a temperature of 32°F until the battery voltage drops to 1.20 volts per cell, or 7.20 volts for a 12V battery. Thus, a 12V battery that carries a MCA rating of 600 CCA tells us that the battery will provide 600 amperes for 30 seconds at 32°F before the voltage falls to 7.20V. Note that the MCA is sometimes referred to as the cranking amperes or CA.

The marine cranking ampere (MCA) rating of a battery is very similar to the CCA rating; the only difference is that while the CCA is measured at a temperature of 0°F, the MCA is measured at 32°F. All other requirements are the same — the ampere draw is for 30 seconds and the end of discharge voltage in both cases is 1.20 volts per cell.

The full form of HCA is hot cranking amperes. It is the same thing as the MCA or the CA or the CCA, except that the temperature at which the test is conducted is 80°F.

Unlike CCA and MCA the pulse cranking ampere (PCA) rating does not have an 'official' definition; however, we believe that for true engine start purposes, a 30 second discharge is unrealistic. With that in mind, the PCA is a very short duration (typically about 3 seconds) high rate discharge. Because the discharge is for such a short time, it is more like a pulse.