With so many different battery types, how do you know whether to recharge them or flatten them every time you use them, and does it matter?

It does matter. Some batteries can be damaged if you use them wrongly, others have a reduced life. Here’s a quick guide.

• Lithium Ion Batteries (Li-ion) are found in all new Apple laptops and ipods. They are also in digital cameras and mobile phones. The more you keep them charged the better. It’s best to never let them run out. They only last about 300 full discharges, so if you let them run totally flat you have used 1/300th of their life. It’s best to charge them as often as you can. Whenever you are not using them put them on the charger. Keep them cool while charging.
• NiCad batteries are exactly the opposite. It is best to let them run totally flat each time you use them. They are found in older cordless drills, older laptops and some cordless phones. If you recharge them before they are fully flat they will ‘remember’ where you discharged them to. So if you keep charging them when they are half empty, you’ll find they will stop working when they are half empty.
• NiMH batteries are like Nicad batteries but the ‘memory’ effect is not as bad. You should still discharge them fully but it won’t hurt them quite as much if you don’t. If you cant’ do it every time, try to fully flatten them occasionally.
• Car batteries (lead acid batteries – also in some camcorders) are the worst for being damaged when fully flat. Every time they go fully flat it does irreversible damage – 3 or 4 times and they will be totally wrecked. Like a lithium ion battery, it’s best to keep them as charged as fully you can.