What is the best battery for the hybrid car?
The early HEV models used lead acid batteries because there was no alternative. Today, Honda and Toyota employ nickel-metal-hydride (NiMH). This chemistry is lighter and environmentally friendlier than lead-based systems. The battery consists of cylindrical cells that are connected in series to attain several hundred volts. The cell strings are suspended in mid air to allow air-cooling.
One of the critical battery requirements for hybrid applications is longevity. Rechargeable batteries for consumer products typically last for two to three years. This short service life is no major drawback with cellphones, laptops and digital cameras because the devices get obsolete quickly. At $2000 to $3000 per battery pack, the replacement cost of an HEV battery would constitute a major expense.
Most batteries for HEV are guaranteed for eight years. To meet this long service life, the cells are optimised for longevity, and not size and weight, as is the case with portable applications. Since the battery runs on wheels, the increased weight and size is not too critical.
A NiMH for an HEV can be charged and discharged 1000 times if done at an 80% depth-of-discharge. In a hybrid vehicle, a full discharge seldom occurs, except if the owner lives on a mountain and requires all available battery power to commute home. Such a routine would add stress to the battery and the life would be shortened. In most other applications, the hybrid car only uses 10% of the rated battery capacity. This allows thousands of charge/discharge cycles. Batteries in satellites use a similar system in which the battery discharges less than 10% during a satellite night. NASA achieves this by over-sizing the batterymore info
One of the critical battery requirements for hybrid applications is longevity. Rechargeable batteries for consumer products typically last for two to three years. This short service life is no major drawback with cellphones, laptops and digital cameras because the devices get obsolete quickly. At $2000 to $3000 per battery pack, the replacement cost of an HEV battery would constitute a major expense.
Most batteries for HEV are guaranteed for eight years. To meet this long service life, the cells are optimised for longevity, and not size and weight, as is the case with portable applications. Since the battery runs on wheels, the increased weight and size is not too critical.
A NiMH for an HEV can be charged and discharged 1000 times if done at an 80% depth-of-discharge. In a hybrid vehicle, a full discharge seldom occurs, except if the owner lives on a mountain and requires all available battery power to commute home. Such a routine would add stress to the battery and the life would be shortened. In most other applications, the hybrid car only uses 10% of the rated battery capacity. This allows thousands of charge/discharge cycles. Batteries in satellites use a similar system in which the battery discharges less than 10% during a satellite night. NASA achieves this by over-sizing the batterymore info
posted by anthony m, at Wednesday, April 18, 2007
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