how can you care for your battery to get the maximum life out of it

Always use your laptop on a hard surface.
Laptops are portable and it's easy to set your laptop on your ibm thinkpad r52 battery or on your bed and use it at your lesiure. That's one of the benefits of having a portable computer. Flexibility. But if you want to extend your battery life you have to watch out for overheating your laptop.
Heat is one of the biggest obstacles to battery life longevity. Your laptop computer fan cannot circulate the air properly when your laptop is sitting on soft surface.
2.) Do not keep your battery installed when you use your laptop on AC for an extended period of time.
While your laptop is undoubtedly using a smart charger to charge your battery even a constant trickle charge over months can reduce your battery life. For best results, only charge your ibm thinkpad t41 battery when you need to charge it, don't leave the laptop battery plugged in all the time.
More importantly than the trickle charger affect is the 'storage' of a Li-Ion battery at elevated temperatures. The optimum storage temperature for a Li-Ion ibm thinkpad t61 battery is at 0 deg. C. The optimum storage charge level is about 40%. Unfortunately we tend to store fully charged and at the temperatures found in a running laptop you'll find a significant reduction in battery for your laptop performance after only 12-18 months.
3.) Use a full charge cycle before recharging
Li-Ion and NiMH battery (ibm thinkpad t61p battery), do not have a memory which you might find in NiCad batteries. However, each chemistry has a limited number of charge cycles, so use a full charge cycle before re-charging to maximize your IBM ThinkPad R52 Battery usage.
Because this may be very difficult to manage, you'll need to consider the cost-benefit ratio for keeping track of how far discharged the battery is before you charge it again.
4.) Be careful where you store your laptop
This goes back to the heat issue. Don't leave your ibm thinkpad x41 battery in the car where it can get very hot.Batteries hate heat and your battery will go on strike permenantly if you expose it to too much heat.
Remember that all laptops are not created equal. You may have gotten 4 hours from your last laptop while on laptop battery , but your new laptop might pull more juice to run that gaming quality processor, or the power hogging programs you're running now. Read your owner's manual to find out what you should expect from your laptop battery and be sure to compare apples to apples when purchasing a replacement lenovo 3000 c100 battery. Not all laptop batteries are made to the same specs. We recommend buying a battery that has at least as much capacity as your original battery (that's the mAh rating), and preferrably the same chemistry as well.