De-mystifying Lithium Ion Battery Care

While reading "Mastering the Nikon D90" recently, I came across a recommendation in the book that asked users to recharge the battery whenever it went down to 25% power. Since the recommendation ran counter to the urban legend of "completely discharging and recharging" a battery, I thought I'd investigate the topic a bit. I came up with the following do's and dont's that some of you may find useful.

Do's

1. Lithium Ion batteries do not suffer from the memory effect. So you can charge them anytime without waiting for it to discharge down to 20% or less of capacity.
2. Use the battery regularly.  As a corollary, you may want to buy batteries only when you are ready to use them, rather buying and storing them for possible future use.
3. Keep the firmware on your device updated - developers may have optimized your device to draw less power. (The last two recommendations are from Apple's iPhone page.)
4. Fully discharge (~0%) the battery and then fully recharge (~100%) approximately every 30 cycles. However, do not fully discharge the battery and then store it for an extended period of time. You may not be able to recharge it!
5. If you are storing a battery, keep it at 40% charge in a cool place, say in a refrigerator - but not the freezer! (The last two recommendations are from Battery University.)

Dont's

1. Don't continuing charging a battery after it has attained a full charge.
2. Don't expose the battery to extreme heat or direct sunlight. Be aware of the green house effect in your car or home.
3. Keep the batteries warm on cold days. When you are ready to use the battery on a cold day, you will have more of the battery charge left if you have kept it warm. (The three points above are from page 249 of the Nikon D90 user manual).
4. Don't frequently discharge the battery completely.
5. If possible, don't charge or discharge the battery at a high rate. For example, you may be able to avoid a high discharge rate in a camera by reducing the use of the LCD screen. (The last two recommendations are from Battery University.)

Related Articles

• Nikon under-documenting the D90 SLR (hitechenergy.blogspot.com)