Rechargeable: Difference between revisions
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===Lithium Iron Phosphate (LiFePO<sub>4</sub>) - 3.3V/cell=== | ===Lithium Iron Phosphate (LiFePO<sub>4</sub>) - 3.3V/cell=== | ||
New | New LiFePO<sub>4</sub> batteries have about 20% lower energy density than Li-ion, but also have much longer life (typically about 10 years, as opposed to 2-3 years for Li-ion) and can endure almost double the number of charge/discharge cycles of Li-ion. They also have lower self-discharge rate, are able to deliver higher current, and are more resistant to thermal runaway. However, as they are not as popular as Li-ion, they are still somewhat more expensive. Because they can not be charged to 4.2V, they require a special charger (or hobby charger that can be set to 3.6V max). Walmart sells 3.2V AA-sized LiFePO4 cells by Westinghouse for solar lighting (so no charger included). | ||
===Lithium Manganese (LiMn) 3.7V/cell=== | ===Lithium Manganese (LiMn) 3.7V/cell=== | ||
These cells allow higher drain (5C) than li-ion cells without some of the dangers. AW sells these as IMR, and Sony as Konion. They can be charged in most li-ion chargers, but some li-ion chargers will overcharge LiMn cells. LiMn cells should be charged at 1C to 2C. Due to lower overall capacity, these batteries fill a niche with flashlights demanding very high current where runtime isn't that important. While they are safer than lithium-ion cells, they can still be made to explode if provoked sufficiently, unlike the | These cells allow higher drain (5C) than li-ion cells without some of the dangers. AW sells these as IMR, and Sony as Konion. They can be charged in most li-ion chargers, but some li-ion chargers will overcharge LiMn cells. LiMn cells should be charged at 1C to 2C. Due to lower overall capacity, these batteries fill a niche with flashlights demanding very high current where runtime isn't that important. While they are safer than lithium-ion cells, they can still be made to explode if provoked sufficiently, unlike the LiFePO<sub>4</sub> cells which cannot. | ||
=== Sealed Lead-Acid (SLA) - 2.0V/cell=== | === Sealed Lead-Acid (SLA) - 2.0V/cell=== | ||
A classic rechargeable battery where cells are hooked up in series to generate higher voltages. A 6V battery would have 3 cells and a 12V would have 6. They are sometimes used in [[Terminology#HID|HID]] lights, but not for more portable lights due to poor size/weight characteristics. However, SLA batteries are very reliable if kept topped up, cheap, and as such, often still used in cars, if not torches. | A classic rechargeable battery where cells are hooked up in series to generate higher voltages. A 6V battery would have 3 cells and a 12V would have 6. They are sometimes used in [[Terminology#HID|HID]] lights, but not for more portable lights due to poor size/weight characteristics. However, SLA batteries are very reliable if kept topped up, cheap, and as such, often still used in cars, if not torches. | ||