BATTERIES THAT SUPPORT STOP START

CAR BATTERIES

Enhanced Flooded Battery (EFB)
Enhanced Flooded Batteries were developed for use in stop-start vehicles. The reduced cost of manufacturing EFBs is attractive for manufacturers in order to help keep overall new vehicle production costs down. The EFB design incorporates a porous fibre material, sometimes called "scrim", along with plates that are thicker than a conventional flooded battery.

The use of low pressure contact material on the plates of EFBs retains the active material and improves their cycle performance which is necessary for stop-start applications. Examples of vehicles using an EFB include the Mazda CX-5, Subaru XV and the Ford Fiesta ECOnetic.

Enhanced Flooded Batteries were developed for use in stop-start vehicles. The reduced cost of manufacturing EFBs is attractive for manufacturers in order to help keep overall new vehicle production costs down. The EFB design incorporates a porous fibre material, sometimes called "scrim", along with plates that are thicker than a conventional flooded battery. The use of low pressure contact material on the plates of EFBs retains the active material and improves their cycle performance which is necessary for stop-start applications. Examples of vehicles using an EFB include the Mazda CX-5, Subaru XV and the Ford Fiesta ECOnetic.

Absorbent Glass Mat (AGM) Batteries
The fastest growing type of Valve Regulated Lead Acid (VRLA) battery is commonly referred to as the Absorbent Glass Mat (AGM) battery. This low-maintenance lead acid rechargeable battery does not require regular addition of water to the cells.
Even though AGM batteries are sometimes called Sealed Lead Acid Batteries, they always include a safety pressure relief valve. As opposed to vented batteries, a VRLA or AGM battery will not spill its electrolyte if turned over. These batteries use much less electrolyte (battery acid) than traditional lead-acid batteries, so they are also sometimes referred to as "acid starved" batteries.

Recombinant battery

The term "valve regulated" is more accurately a "recombinant" battery, which means that the oxygen produced at its positive plates will largely combine with the hydrogen that is ready to be produced on the negative plates. This creates water and prevents water loss. Since the battery system is designed to be recombinant and eliminate the emission of gases on overcharge, room ventilation requirements are reduced and no acid fumes are emitted during normal operation.

The valve is a safety feature in case the rate of hydrogen production becomes dangerously high. This is in contrast to antimony and hybrid flooded cell battery types, where gases escape before they have a chance to recombine, so water must be added on occasion. VRLA cell batteries have a pressure relief valve which may activate when the battery is recharged at a high voltage level, typically more than 2.3 volts per cell.
The battery cover has a gas diffuser built in to allow for the safe dispersion of any excess hydrogen that is formed during overcharging. An AGM battery can be oriented in any manner as opposed to traditional flooded cell batteries which must be kept upright to avoid acid spills and migration.

AGM cells may be made of flat plates similar to a conventional flooded cell battery, or it may also be made in a spiral roll form which results in cylindrical cells. At high overcharge currents, electrolysis of water occurs, expelling hydrogen molecules and oxygen gas through the battery's valves. Care must be taken to prevent short circuits and rapid charging. Constant-voltage charging is the most efficient and fastest charging method. AGM batteries may be continually "float-charged" at around 2.35 volts per cell (14.1 volts in a 12 volt battery) at 25 degrees Celsius.
One of the best reasons to use an AGM battery in hybrid and stop-start applications is its ability to deliver a very high current in a relatively short period of time. This ability is due to the slightly compressed nature of the electrolyte impregnated glass mats being held against the active material in the AGM battery's grids.

AGM battery advantages include:

• Can be mounted in the passenger compartment or other areas of a vehicle that would otherwise be sensitive to gassing produced by conventional lead-acid batteries
• Able to deliver significantly more cycles demanded by stop-start systems
• Able to support vehicle systems that experience large parasitic drains and partial states of charge