I could easily have spent a fortune replacing the motherboard, the memory, the processor etc when it all came down to 2 dollar battery. What's more is these batteries are easy to get. What you need is a CR2032 available at most hardware stores like home depot and I've even seen them sold in Safeways. Of course every reputable computer lithium ion battery stocks store should stock them. Just check to make sure that your PC uses a CR2032 before you go to the shops!
The battery will over-charge if left attached to the charger. The battery stops charging automatically when full lithium facts so it will not over charge. If the battery is left on charge too long it is possible that heat will damage the battery.
The price of an external laptop battery may vary from brand to brand. But they are quite affordable and very compact device. They can be recharged with an external charger so you don't have to look out for an electric supply to charge the external battery.
On the second point, iPOD batteries are smart charging. Now, you can't use your iPOD Nano battery to help study for a test! Rather, they're smart because they can tell the charger when they're almost full. When your iPOD is charging, it charges up to 80% capacity in no time flat. Then the iPOD battery tells the charger to slow down so the charging process goes lithium bettery stock from warp speed to snail's pace. This ensures that the battery doesn't overcharge, and makes certain that you're spending your time with your music, and not spending your cash on iPOD batteries.
The only drawback on this type of lithium based battery is the high cost. Since it is expensive, it makes sense to use it the right way to extend its service life.
Today, many of the latest computers have a fast recharge feature where you can recharge 90 percent of the battery power by charging it for around one hour. The balance 10 percent is recharged slowly. If your laptop has this facility, do use it. This helps to extend the life of the battery. However, do not recharge the laptop battery until it has less than 30 percent charge remaining.