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.
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
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.
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
http://thomasdistributing.com/ and find out that the new NiMH's have
significantly higher milli-amps so I get a new set.
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.
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