Almost all kinds can be restored to some extent. Below is a simple way to restore your laptop's battery in 4 steps.
1. Identify the type.
Remove the battery from your laptop and identify what type it is. It will be printed on the case somewhere, and will be either a Nickel Cadmium (NiCd,) Nickel Metal Hydride (NiMH,) or Lithium Ion (LiON.). If it is one of the first two types then this technique is the one to use. If however it is a Lithium Ion type then do not use the following technique, as it will have at best no effect, or at worst can damage your battery.
Nickel Cadmium and Nickel Metal Hydride types both suffer from what is called a memory effect, repeated partial discharge and recharge can cause the battery to 'remember' the point at which recharging usually starts, and set this as its base point. This false empty reduces the amount of charge the unit can hold.
The following technique resets the battery, and removes any memory effect, restoring it to near full capacity.
2. Fully Discharge.
There are two ways to achieve this, one involves shorting out your batteries terminals using a special resistive circuit, this fully discharges the power stored safely, and fast. It is important you either buy this tool, or make one from plans (if you are technically gifted.) Never just short out the terminals without this special circuit, as a massive current would be produced, which is dangerous, and can cause a fire or damage the battery beyond repair.
If you don't have this tool then you can fully discharge it by placing it in your laptop, and then entering its setup screen. Usually this is achieved by pressing Del just after switch on. Leave the laptop in this settings mode until it switches itself off due to low power, as this screen bypasses any power saving settings it will be fully flat.
Overnight place your battery in the freezer. Place it in a zip lock bag to prevent it coming into contact with any moisture first. Doing this will cool the gel in it and this will remove any memory effect. Once you remove the unit from the freezer, allow it to return to room temperature, make sure it is dry and then recharge it in your laptop.
Repeat the last two steps, and fully discharge and freeze the cell once more. After the second charge you should see a vast improvement in the performance of your unit.
This is just one of the many techniques you can use to recondition rechargeable batteries. By following these methods you can restore your laptop's battery in 4 steps. Laptop batteries can be expensive, so doing this will save you money, and also keep them out of landfill so you help the planet too.
If you want to to discover more about how to restore or recondition old batteries that you thought were dead, and were going to throw away. Go to the recondition old batteries guide. Take a look at www.reconditionoldbatteries.blogspot.com for more information.