Leaf separators

The term leafseparator characterizes the customary stiff version of a starter battery separator that can be inserted individually between the electrodes on automatic stackers, in contrast to pocket separators. This processing requires considerably 

Brand name Backweb thickness (mm) Electrical resistance (mS2 cm ) Oil corrterrt (%) Porosity (%) Puncture strength (N) Supplier 

The first synthetic separator is still in use today in some geographical areas, for two reasons this separator is unchallenged in its low raw-material and production costs 

Other back web thickne.sse.s upon reque.st n.a. not available 

Sintered PVC is not at all one uniform product large differences in properties and quality are possible. Experience has shown that premium qualities require significantly higher production costs. 

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Typical pore size distributions result in mean pore diameters of around 15 //m. Even long and intensive efforts did not succeed in decreasing this value decisively in order to enable production of micropo-rous pocketing material resistant to penetration [65, 66], In practice PVC separators prove themselves in starter batteries in climatically warmer areas, where the battery life is however noticeably reduced because of increased corrosion rates at elevated temperature and vibration due to the road condition. The failure modes are similar for all leaf separator versions shedding of positive active mass fills the mud room at the bottom of the container and leads to bottom shorts there, unless — which is the normal case — the grids of the positive electrodes are totally corroded beforehand. 

The closest relative to the wood veneer surprisingly has retained some of its properties, which differentiate these separators from pure synthetic ones primarily, a positive effect in reducing the water loss in starter batteries [39, 70-72], This impact tends to decrease as the antimony content in the alloys is lowered, but it still represents an advantage over other leaf separators, unless a microporous pocket is required by the alloy anyway. 

Glass fiber leaf separators in the USA -especially at one large manufacturer-were for over a decade, between 1980 and 1995, an intermediate in the transition from conventional leaf separator to microporous pocket. The web is produced... 

Microfiber glass fleece mats are typically produced from a blend of 20 - 30 percent glass microfibers <1 //m in diameter, with the balance of the glass fibers thicker (3 - 10 //m) and longer (cf. Fig. 1), on a specialized paper machine (Fou-drinier), since this is the only way of achieving the desired tensile strength without binder. The material is supplied in roll form, even though it is normally not processed into pockets, which are not required due to the absence of free electrolyte. The classification here as a leaf separator should be seen in this sense. 

Because of the increased shedding with these alloys, pure leaf separation is hardly suitable. Separations with supporting glass mats or fleeces as well as microfiber glass mats provide technical advantages, but are expensive and can be justified only in special cases. Also under these conditions of use the microporous polyethylene pocket offers the preferred solution [40]. Lower electrical properties at higher temperatures, especially decreased cold crank duration, are battery-related the choice of suitable alloys and expanders gains increased importance. 

Polyethylene pocket separators Sintered PVC separators Cellulosic separators Cellulosic/ glass mix separators Glass fiber leaf separators... 

The simplest cell consists of one negative, one positive, and one separator between them. Most practical cells contain about 3 to 30 plates with separators in between. Individual or leaf separators are generally used. The use of envelope separators, whieh surround either the positive or negative plate, or both, is becoming more popular in small, sealed eells, SLI, motive power, and standby batteries to facilitate production and to control lead contamination during manufacture. 

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