Voltage

• Some hybrid car batteries are constructed of metal hydrides which use very high voltages. This level of voltage could electrocute people in a collision if the battery wires become exposed.
  
  

Inconvenience

• Older hybrid models use batteries that require recharging at least every two weeks can be inconvenient.
  
  

Replacement Cost

• Another disadvantage of hybrid car batteries is they may need replacing after 150,000 to 200,000 miles. This is much less frequent than for a standard car battery, but hybrid car batteries also are much more expensive, running up to $3000 as of 2009.
  
  

Cold Weather

• Some hybrid car batteries do not work as efficiently in cold weather, so the hybrid car owner does not save much on gas in these conditions.
  
  

Speed

• Drivers looking for high-performance speed will not want a hybrid. The heavy batteries add excess weight to the car, and the cars have a smaller internal combustion engine to maximize efficiency.