As the demand for hybrid vehicles grows, Chrysler has been forced to momentarily shelve their hybrid testing. Tests found the batteries overheated in some of the pickup trucks. 109 truck models and 23 minivan models with plug-in hybrid technology are no longer currently testing.

Don't overcharge the device. Safety circuits take care of this problem but you shouldn't keep it on charger for weeks at a time anyway. Overcharging is just as bad cobalt mine as complete discharge.
 

OLithium Polymer - The latest and greatest being used in cell phones. They have a higher power density than the other types. This allows manufacturers to provide either a thinner or lighter battery, or some combination of both. They can be hard to find. They are available for several Samsung phones. Lithium mines Ontario Polymer batteries do not suffer from the poor memory effect and can be recharged anytime.

Toshiba laptop batteries are excellent for this. They make it easy to have a spare battery for a laptop for many reasons. One is that they make batteries with high capacity. They are lithium-ion batteries. A Li-ion battery lasts longer than other batteries do. Because of that, they have a longer use life as well as not having to be replaced as often.

This cordless driver comparison showed that Lithium-ion batteries hold a charge a lot longer than a nicad battery. A fully charged Lithium-ion batteries can hold a charge for up to a year. My cordless driver comparison did clarify to me that when comparing drivers its important to compare cordless drivers with similar power. Power wise a 12 volt Nicad battery has the same power as a 12 volt Lithium battery stocks ion battery and a 18 volt nicad battery has the same power as a 18 volt Li-ion battery. So don't expect the same torque found in a 18 volt nicad cordless drver from a new 12 volt li-ion cordless driver.

Why Lithium-ion battery? Because it provides high energy density, runtime, and is light in weight. To run a power-sucking laptop, a battery with high energy density is required. The runtime of a laptop battery is based on what sort of applications you run. If you run basic applications for writing, reading, copying, chatting, etc, then your laptop battery runtime will be high compared to running a complex application that has a huge number crunching requirement.

A used battery must be disposed of properly. Do not crush or throw a battery into a fire. This could lead to a major accident because the battery could explode.