Lead Acid Battery Formatting and Priming

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Jan 31, 2006
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Not all rechargeable batteries deliver the rated capacity when new, and they require formatting.......

“What’s the difference between formatting and priming?” people ask. Both address capacities that are not optimized and can be improved with cycling. Formatting completes the fabrication process that occurs naturally during use when the battery is being cycled. A typical example is lead- and nickel-based batteries that improve with usage until fully formatted. Priming, on the other hand, is a conditioning cycle that is applied as a service to improve battery performance during usage or after prolonged storage.

Formatting a lead acid battery occurs by applying a charge, followed by a discharge and recharge. This is done at the factory and is completed in the field as part of regular use.......Lead acid typically reaches the full capacity potential after 50 to 100 cycles.

Deep-cycle batteries are at about 85 percent when new and will increase to 100 percent, or close to full capacity, when fully formatted. There are some outliers that are as low as 65 percent when tested with a battery analyzer.

The function of a starter battery lies in delivering high load currents to crank the engine, and this attribute is present from the beginning without the need to format and prime. To the surprise of many motorists, the capacity of a starter battery can fade to 30 percent and still crank the engine; however, a further drop may get the driver stranded one morning.
 
Lead acid is not in as big of need of this as NiMH is.

With lead acid it is noticeable on large battery powered equipment. Floating the bank long enough is also important to the health.
 
I've witnessed this several times on my own new batteries. Their voltage retention under light or heavy loads when new is poor compared to after they have been cycled fairly deeply and then truly fully recharged. The TPPL AGMS need this to be a full recharge with an initially high rate.

Afterwards they hold higher fully charged resting voltages and hold higher voltage during engine starting and longer discharges at much slower rates.

Those just assuming the battery they bought is fully charged and at peak performance are misinformed. The lead acid battery can benefit significantly by a a few initial intentional deeper cycles followed by prompt and true full recharges, though the latter part is often impossible with off the shelf smart chargers.
 
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