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Old 11-07-07, 09:18 AM   #1
dekindy
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Several battery questions

I read in wikopedia that Li-ion batteries experience permanent capacity loss beginning at date of manufacture, regardless of use. It outlined a 20% loss per year if stored at room temperature with a 100% charge. Only 2% loss per year was experienced if stored in the refrigerator with a 40% to 60% charge. Are these facts true?

I am planning two night rider per week. I could do both without recharging between the rides. Should I fully charge the battery, ride both rides without recharging, store the battery in the refrigerator, and wait to full charge right before my next ride?

Should I store fully charged nihm batteries in the refrigerator to slow the discharge?

I have the Fenix L2D CE Premium Q5 flashlight and various blinkies.

Should I get the highest capacity rechargeables for the flashlight or hybrids? I am concerned about the discharge rate and the resulting damage to the cells. I will be using the flashlight a couple times a week in the winter but none at all in the summer and have no frequent high use applications. I suppose I could keep them on a charger all the time, but that might be a hassle that would not be justified by the longer run time. I need at least 2 to 2.5 hours run time without changing batteries. I think the RayOVac hybrids are 2100 mah and are currently the highest capacity hybrid?

Are rechargeables okay for blinkies or stick with regular batteries? I am thinking the hybrids would be best for the blinkies if rechargeables are appropriate?

Last edited by dekindy; 11-07-07 at 09:29 AM.
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Old 11-07-07, 10:42 AM   #2
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Carry rechargeable spares, that should take care of your runtime. Buy the highest quality batteries and charger you can afford that meets your needs. Rechargeables are fine for blinkies, less cost long term, and less waste versus alkalines.

Don't overthink discharge rates, putting them in a refrigerator won't help unless you're not using them for 6 months. A good charger will minimize those drawbacks and maximize the performance and lifetime of your batteries.

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Old 11-07-07, 10:51 AM   #3
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Rechargeable AAs are fairly cheap. Buy some and use them. When they die replace them. It's really easy to over think these things.....
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Old 11-07-07, 01:47 PM   #4
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Quote:
Originally Posted by dekindy View Post
I read in wikopedia that Li-ion batteries experience permanent capacity loss beginning at date of manufacture, regardless of use. It outlined a 20% loss per year if stored at room temperature with a 100% charge. Only 2% loss per year was experienced if stored in the refrigerator with a 40% to 60% charge. Are these facts true?
All batteries work by a chemical reaction to produce electrons. Some of the reactions are reversible and the battery can be recharged. Some of the reversible reactions go wrong and become irreversible, eventually leading to the cell dying because it can't be recharged. Lead and NiCd can take a very long time, if properly treated, to die from this kind of problem. NiMH takes less time than NiCd and Li-ion even less. Storing the battery in cool conditions can slow down the aging process but not stop it. NiMH has a problem with being stored in high ambient temperatures but stored under 'normal' conditions aging really isn't an issue.

Buchmann says that Li-ion should be stored for long periods of time because they do degrade. I don't use Li-ion partly for this reason. NiMH will degrade over time but they are much cheaper to replace.

Quote:
Originally Posted by dekindy View Post
I am planning two night rider per week. I could do both without recharging between the rides. Should I fully charge the battery, ride both rides without recharging, store the battery in the refrigerator, and wait to full charge right before my next ride?
The battery is going to age no matter what you do. Li-ion don't have issues with being recharged after being partially discharged like NiCd. Personally, I rather have a fully charged battery in case something goes wrong and I'm out longer than expected then trying to get home on that last little bit of energy. Or, alternatively, forgetting to recharge and not having the light. Recharge it after use and have peace of mind.

If you are not using the battery for a while...weeks to months... discharge to about 40% and store it in the 'fridge or a cool place. Otherwise, use the battery as much as you can before it ages out on you

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Should I store fully charged nihm batteries in the refrigerator to slow the discharge?
They don't need to be that cold. Don't store them in the attic in the summer but you could store them in the basement.

Quote:
Originally Posted by dekindy View Post
I have the Fenix L2D CE Premium Q5 flashlight and various blinkies.

Should I get the highest capacity rechargeables for the flashlight or hybrids? I am concerned about the discharge rate and the resulting damage to the cells. I will be using the flashlight a couple times a week in the winter but none at all in the summer and have no frequent high use applications. I suppose I could keep them on a charger all the time, but that might be a hassle that would not be justified by the longer run time. I need at least 2 to 2.5 hours run time without changing batteries. I think the RayOVac hybrids are 2100 mah and are currently the highest capacity hybrid?

Are rechargeables okay for blinkies or stick with regular batteries? I am thinking the hybrids would be best for the blinkies if rechargeables are appropriate?
A year ago, I would have said not to use NiMH in blinkies. The self discharge rate was just too high. Self discharge of Ni chemistry batteries is what kills 'em. But the new low self discharge NiMH batteries are changing all that. They use an new separator that keeps them from discharging so quickly and makes them better for applications like blinkies where you don't use much power each time and they need to sit idle for long periods. However the cost of the batteries isn't cheap and you'll need a charger for them. If you only have one blinky...i.e. 2 batteries...it makes sense. If you have 2 blinkies, it still might make sense. But if you have 8 to 10 of them (3 on me, 1 on 4 bikes and maybe a couple of others) and various battery configurations and sizes, it could get expensive pretty fast. A pack of 4 batteries at Radio Shack is $4. For 10 lights that's $20...pretty cheap.
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Old 11-07-07, 02:02 PM   #5
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I have no scientific knowledge of the breakdown, etc . . . but here is my $.02 (hi Dwight)

I agree with others . . . do not over think it. Nothing is going to last forever and really the price of most of this stuff is not that significant, especially when you look at the value you get. You ride 2 nights a week for a few hours. You are getting your money out of the equipment.

I also recommend a fully charged light every time you go out. The alternative is just not worth it, even if this practice would be harder on the batteries.

I personally do not expect any battery to be of much use after 2 or 3 years. This is for bike lights, cell phones, laptop batteries, etc. If I could slightly slow the decay process but it took me more effort (only charging at certain levels, storing in fridge, etc) then it is not worth it to me.

I charge my batteries and ride. I do nothing special otherwise. One day they will need to be replaced. Life goes on.
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Old 11-07-07, 04:00 PM   #6
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Don't forget to recycle those batteries instead of throwing them out!

I use Li-Ion because I like to top up the battery every night when I get home. If I had to wait until they were sufficiently discharged I'd probably end up riding without lights 20% of the time.
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Old 11-08-07, 07:36 AM   #7
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How do you like your Fenix?
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Old 11-08-07, 08:06 AM   #8
dekindy
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How do you like your Fenix?
http://bikeforums.net/showthread.php?t=359541
review here.

Do a search on fenix. Limiting it to titles only will get you plenty of information.
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Old 11-09-07, 06:40 AM   #9
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A excellent source of reliable battery information is the Battery University. More than you ever wanted to know. See it at http://batteryuniversity.com/partone.htm. There is discussion in both part one and part two about Lithium Ion batteries as well as all other battery chemistries. Try it you'll like it!
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Old 11-09-07, 07:17 AM   #10
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A excellent source of reliable battery information is the Battery University. More than you ever wanted to know. See it at http://batteryuniversity.com/partone.htm. There is discussion in both part one and part two about Lithium Ion batteries as well as all other battery chemistries. Try it you'll like it!
Thanks.
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