I have a set of four rechargeable AA batteries for my digital camera. One of the four will not hold a charge. I recall reading that batteries should not be mixed, although I don't know if that means not to mix fully charged with partly charged, or if it refers to mixing brands or models. Can I replace the one bad one with a new battery or do I have to throw them all away and start fresh? Thanks.
First try rapping the bad battery on a table. I have had success in the past.
Lou
I mix brands all the time. I'd not mix alkaline and ni-cads though.
Some chargers custom charge each battery and others tend to charge all the batteries the same. If you have the more advanced charger then you can mix batteries by brand capacity and remaining charge when charging (See charger instructions.)
I don't recommend mixing different kinds (brands or capacities) or batteries with different current charge levels in the camera, flash etc.
It depends, how old and how many cycles do they have, what do the batteries fully charge to in volts. My new Sanyo Eneloop NiMh charge to about 1.53, when I junk them they only take near 1.3 or so. 100 charges and you have lost most of their best life. They say 1000 charges, but what you get after 100- 150 or so is only a few photos and they self drain fast overnight. For a casual shooter, like once a month try Sanyo Eneloop. mine hold charge for 4- 7 months before I even think of charging them. If you mix batteries match them by voltage after a charge and amp rating. One bad cell to me means they are all heavily used and not worth alot of effort.
With alkalines, mixing could cause leakage. That doesn't seem to be a problem with rechargeables.
I don't know what kind of charger you have and whether the cells are NiCad or NiMH. The old overnight chargers could cause serious self-discharge within a year. A cell would discharge itself within a few days of charging, or perhaps it wouldn't charge at all.
Fast chargers greatly reduce this problem, but a fast charger should have an indicator light for each cell. If it has two or more cells in one circuit, it will shut off when the first cell is charged. At that point, the other cell may be only 1/10 charged, and you might think it was a bad cell.
If cells aren't charging properly on a fast charger, fully discharging each cell before charging can fix the problem. I use a one-cell holder with a 2-ohm resistor. Memory effect can also make a NiCad look useless. Discharging overnight can restore a cell with memory effect.
I can't vouch for this, from personal experience. But, what I've read is that when one battery goes dead before the others, it does "voltage reversal" or something. Which more completely kills the battery.
The ideal answer is to replace them all as a set. With the economy being a mess, replace one might work. However, at the store, you have to buy 2 or 4 batteries. Might be easier to just get a set of 4, and be done with it. I hate being at the McDonalds playland with the kids, and have to run out to the truck for a change of batteries.
A neighbor bought a 24V NiCad drill. It came with two battery packs and instruction to switch batteries at the first sign that one was getting low.
The first time he used it, I reminded him to change batteries when I saw a reduction in power. He kept drilling. Continuing to run current through a discharged cell could ruin an expensive battery pack.
That may not be a problem with cameras. I imagine a camera will quit working if it's not getting full voltage.
Get a set of new ones, and you can mix them so long as they are all nimh.
Steve
Be interesting to know how long the battery packs last.
I'd try to keep the charge/discharge more or less even. I buy my NiMH batteries 12 at a time & keep them in a 3 sets of 4. Usually by the time one cell goes bad [hundreds of cycles] I check
If your batteries aren't holding a charge- be sure to check your charger. Make sure all contacts are clean and that it is made to maintain a charge in whatever kind of rechargeable you're using.
Jim
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