Originally published at: http://www.howtogeek.com/179486/ask-htg-should-i-store-my-batteries-in-the-fridge/
Some people swear by storing their batteries in the refrigerator to extend the lifespan of the battery and, apologies for the obvious food-storage joke, keep them fresh. Does it actually help? Is there any legitimate reason for putting your batteries in cold storage?
The storing of batteries in the refrigerator goes way back to the days of carbon-zinc batteries.
Photographers would do this quite frequently as their high priced batteries for the strobes that were in use in the 50s and 60s were subject to self-discharge.
In recharging my NiMH batteries, I notice that at the end of the charge cycle that the batteries are quite warm to hot. As batteries charge and become warm they increase in resistance as with all electrical devices heat cause resistance. Letting them cool down allows me to recharge them once again. Repeating this process several times (generally 4) allows the batteries to take on more charge (current) which gives a longer use (up to 25%). For a quick cool down I sometimes place them in the freezer not exceeding a half hour. When I use the batteries (AA) I have noticed that they have exceeded the normal use of 45 minutes in my camera to 1 hour sometimes 1:20. Again as current is removed they tend to heat up to a point of uncomfortable to touch. The uncomfortable to touch is a danger point of any electrical device and use should be terminated. I do NOT recommend long term storage of batteries in cold for the same reasons previously stated. However in the method I have described, a bit of an extra charge may be obtained. Remember the uncomfortable to touch thought. Always check your charger for excess heating as often as possible and the device in which they are being used.
You are killing your batteries! If they are getting anything more than slightly warm at the end of the charging cycle, you are charging them at too fast a rate with too high a charging current. 200mA is the fastest you should ever charge AA NiMH batteries. While your method of charging batteries may seem to be giving you more charge life, in the long run, your batteries are going to die sooner than they would have otherwise. Besides, all that cool down and recharge again rigmarole is more work than the little gain you get will justify. It would be much easier to just carry some spare batteries and change them out when they run down.
If you don't have one already, get a good "smart" charger, such as the La Crosse BC-700. A smart charger does a better job of regulating charging current and will taper off the charge toward the cycle to avoid overheating, preventing damage to the battery (as you seem to already be aware of, heat is deadly to batteries). Even though the BC-700 has charge rates higher than the default 200mA, you should use them only if you get a "stuck" battery, one that doesn't want to reach full charge. The handful of "stuck" batteries I've run into responded to 500mA, then could be recharged after that at the safer default 200mA.
If you aren't using low self discharge NiMH batteries, I highly recommend Sanyo Eneloops. I have some that are several years old and are still going strong. Unlike regular NiMHs, which can drain themselves in as little as a month, LSD NiMHs, such as the Eneloops, will hold a large percentage of their charge for as much as a year or more. Since a rechargeable battery's life is measured in number of discharge/recharge cycles, the LSDs will last far longer than conventional NiMHs since they will not have to be recharged as often. I have Eneloops that are several years old and still going strong; out of over a hundred AAs and AAAs, I have yet to have one die on me.
Generally at the end of the charge, they are comfortably warm. The ones (2) that have gotten Hot, were immediately discarded, as the heat indicated a potential problem. This probably resulted from having used them in a device that most likely had developed a near short or a short internally as they were very hot when removed from the device. Upon recharging they again got hot and were discarded. The charger was also discarded as it developed a problem as a result. As a veteran electrician of 43 years I do NOT recommend or promote storage of batteries in the fridge or freezers. Though I will check out your device recommendations.
Duracell small batteries now all come with a label that claims a 10-year storage life. I guess you'll have to wait and see.
Duracell makes a recharger that has an auto shutdown on completion. The charging lights change from red to green. I've never had warm batteries with this charger, so I'm guessing it works. The model name isn't on the charger but it's the one that is a clamshell device.
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