A rechargeble cell is 1,2 V, nominal. A battery - say a 7,2 v battery - is =
A
BATTERY of 6 such cells. The problem is that the cells are not equal. (The=
y
can differ +/- 30%!!)
And a chain is never stronger than it's weakest link.
"Weak" means here both driving capacity and charging capacity. Not exactly
equal, means (among other things) - that the inner resistance of each cell
is different, that is - one cell will charge quicker than another, and one
cell will discharge quicker than another.
Finally it means that the cells will "age" differently, and that - if you
match cells in a new battery pack, they will quite soon be different anyway=
.
In my experience: Suppose a cell manufacturer tells that his cell will
charge and discharge at least 1000 times. This is true.
But when 6 such cells are put together, the entire BATTERY (all cells
together!) will perform 100% perhaps only 10 times!! Especially when
fast-charged, the capacity of such a BATTERY may lower very quickly!
This is something that is seldom told publically. Neither is it told that
one battery pack may be excellent, while another may fail almost
immediatelly, and that this is more or less a gamble, out of control also
for the manufacturer!!
When one cell out of 6 is no good, the entire battery is no good.
The solution: All high-current consuming aparatus, such as DAT's, MD's and
videos should - of course!! - run on single, regular 1,2 or 1,5 v cells.
Then you could choose to run it on alkaline or NiCad's or whatever, and you
could choose to charge each cell individually, and in 14 hours, and save
yourselves a lot of money and trouble.
Especially big aparatus should be constructed that way, as there is place
for such a holder.
But it is much more complicated to make a good battery holder for 6 single
batteries, than a holder for a battery pack. And people don't always like
such solutions as "I don't want to have a lot of hazzle with a lot of small
batteries - why can't they have a decent battery pack like everybody else."
For the ones of you who have problems with batteries: Make an external
battery holder for single cells, and slow charge them individually.
A number of such cells, slow charge, individually, will run your equipment
troublefree for at least 500 times. The cells will get old by age before
they are run out.
Klas.
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