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Self-discharge is a chemical reaction, just as closed-circuit discharge is, and tends to occur more quickly at higher temperatures. Storing batteries at lower temperatures thus reduces the rate of self-discharge and preserves the initial energy stored in the battery.
Stage 3 is called the U-phase or float charge state, the voltage is reduced to a value that is safe to be applied for long periods (weeks) without significantly reducing the lifetime of the battery. During this phase, the charge current decreases gradually to a small residual value that compensates for any self-discharge of the battery.
The lead sulfate first forms in a finely divided, amorphous state and easily reverts to lead, lead dioxide, and sulfuric acid when the battery recharges. As batteries cycle through numerous discharges and charges, some lead sulfate does not recombine into electrolyte and slowly converts into a stable crystalline form that no longer dissolves on ...
Peukert's law brings a certain degree of fire-safety to many battery designs. It limits the maximum output power of the battery. For example, starting a car is safe even if the lead–acid battery dies. The primary fire hazard with lead–acid batteries occurs during over-charging when hydrogen gas is produced.
Trickle charging is the process of charging a fully charged battery at a rate equal to its self-discharge rate, enabling the battery to remain at its fully charged level. This state occurs almost exclusively when the battery is not loaded, as trickle charging will not keep a battery charged if current is being drawn by a load.
Cycle durability % # 100% depth of discharge (DoD) cycles Lead–acid: 50–92 [2] 50–100 [62] ... Self-discharge Memory Cycles Times Temperature Weight
Batteries suffer from cycle ageing, or deterioration caused by charge–discharge cycles. This deterioration is generally higher at high charging rates and higher depth of discharge. This aging cause a loss of performance (capacity or voltage decrease), overheating, and may eventually lead to critical failure (electrolyte leaks, fire, explosion).
Generally a rechargeable battery system will tolerate more charge/discharge cycles if the DOD is lower on each cycle. [9] Lithium batteries can discharge to about 80 to 90% of their nominal capacity. Lead-acid batteries can discharge to about 50–60%. While flow batteries can discharge 100%. [10]