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Old Jan 29, 2010, 8:37 AM   #1
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Default Battery Shelf Life

When I purchased my Canon 40D & 7D cameras they came with an extra battery.

If I never charge the 2nd battery how long will it an last? Basically how long would a new battery last on a store shelf. I do not see any use by dates on the new batteries.

Also, what is the typical life of battery that is being used and charged on a regular basis? I have know idea but I am guessing the lithium batteries would last at 2-3 years?

I have not been in a situation where one battery would not last for the whole event so my thought was I would just use one battery until it started to die and then use the second battery. When I am at a sporting event I save power by turning off the display picture function so it only comes on when I want to look at a picture or check something on the menu. My concern with “saving” the second batter would be having a useless second battery after the first battery dies.

Thanks

Tom
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Old Jan 29, 2010, 12:38 PM   #2
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"If I never charge the 2nd battery how long will it an last?" I believe the correct answer is just about as long as the 1st battery. Li-Ion batteries start to decay from the date of manufacture, and not necessarily from use, as opposed to NiMH batteries whose decay is proportional to the number of discharge/recharge cycles.. I believe you can expect closer to 5 years from your batteries.
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Old Jan 29, 2010, 3:49 PM   #3
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Thank you rinniethehum.

“Decay” that was the key word missing in my goggle search to find this information. After a search on Google it appears that my idea for “saving” the spare battery may even be worse than using it. The website http://www.batteryuniversity.com/parttwo-34.htm provides guidelines that partial discharges are better than larger discharges. So it seems that using two batteries in the battery grip could actually extend battery life of both batteries.

Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory.




Guidelines from http://www.batteryuniversity.com/parttwo-34.htm
  • Batteries with fuel gauge (laptops) should be calibrated by applying a deliberate full discharge once every 30 charges. Running the pack down in the equipment does this. If ignored, the fuel gauge will become increasingly less accurate and in some cases cut off the device prematurely.
  • Keep the lithium-ion battery cool. Avoid a hot car. For prolonged storage, keep the battery at a 40% charge level.
  • Consider removing the battery from a laptop when running on fixed power. (Some laptop manufacturers are concerned about dust and moisture accumulating inside the battery casing.)
  • Avoid purchasing spare lithium-ion batteries for later use. Observe manufacturing dates. Do not buy old stock, even if sold at clearance prices.
  • If you have a spare lithium-ion battery, use one to the fullest and keep the other cool by placing it in the refrigerator. Do not freeze the battery. For best results, store the battery at 40% state-of-charge.
Also see
http://en.wikipedia.org/wiki/Lithium-ion_battery
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Old Jan 30, 2010, 10:48 AM   #4
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Tom, in your original message here you said...

Quote:
Originally Posted by schent1 View Post
I am guessing the lithium batteries would last at 2-3 years?Tom
I assume this was a slip, and you meant "lithium-ion" rechargeable batteries. "Lithium" batteries, e.g., Li AAs, throwaway CR-V3, many button cells, are all primary, single-use batteries with a completely different chemistry, involving the permanent oxidation of lithium metal, and have a very long shelf-life.

Lithium-ion batteries do not intentionally contain any metallic lithium, though it can unintentionally and catastrophically appear if they are seriously abused or badly manufactured. It's actually complex cobalt and manganese compounds that are oxidised, and lithium ions that carry the current through the cell.

Safe use involves (a) not trying to recharge lithium primary batteries, and (b) charging lithium-ion batteries using only appropriate charging circuitry!

Wikipedia has excellent articles on both types.

Last edited by Alan T; Jan 30, 2010 at 11:11 AM.
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Old Jan 30, 2010, 12:53 PM   #5
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Quote:
Originally Posted by Alan T View Post
Tom, in your original message here you said...
Originally Posted by schent1
I am guessing the lithium batteries would last at 2-3 years?Tom
I assume this was a slip, and you meant "lithium-ion" rechargeable batteries.
Alan,
Yes, Lithium-ion. Actually it was not a slip at all, I just did not know what I was talking about.
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