On 27 Dec 2005 18:49:53 -0800, Kyle Evans wrote:
> Thanks, everyone, for the replies. I started charging the batteries
> earlier today and it actually took a few hours. What I really wanted to
> know was how do I do a quick charge versus a standard charge? The
> charger just mentions a quick charge but the batteries have both (2.5
> hours and 14 hours). Also, on the batteries, are the times listed the
> amount of time it should take to charge or the amount of time they will
> last with each respective charge? I guess I was thinking that the time
> meant how long they would last with each type of charge, but now
> thinking about it I can see if it means how long it will take to charge
> then it doesn't matter if the charger does a quick or standard charge
> as long as both will give me the same battery life.
Unless you have one of a very small number of chargers (I'm fairly
sure that you don't) that allows the selection of charge rate,
you'll get only what the charger was designed to do. This usually
amounts to the default "quick" charge rate for the first part of the
charge cycle. If you have a so-called "smart" charger, this will be
for a variable amount of time, depending on the capacity of the
batteries, typically ending when the batteries are about 85% to 90%
charged. If you have a no-so-smart charger, the amount of time will
be based on a timer circuit, and when the time limit has been
reached, the batteries might not be fully charged or they might be
overcharged, depending on the batteries that were used. For both
types of chargers, they will then often switch to a much slower
trickle charge rate. What you should know is that you usually have
no say in the matter.
The batteries mention the 2.5 and 14 hour charge times, but that's
pretty meaningless, and is only provided as a clue to how long it
should take to charge the batteries (from a fully discharged state)
if they are charged at the given rates, and usually if you do the
math, you'll see that the charge rate (in amps or ma) times the time
(in hours) is about 40% greater than the capacity of the batteries,
due to inefficiencies in the charging process:
> "Standard Charge: 14 Hrs at 200mA
> Quick Charge: 2.5 Hrs at 900mA"
14 hrs * 200ma == 2,800 maHrs (40% greater than 2,000 mah)
2.5 hrs * 900ma == 2,250 maHrs (only about 10% greater)
I think that this means that to prevent heat damage to the
batteries when quick charging, the manufacturer wants the batteries
to be charged for only 2.5 hours at the 900 ma rate, leaving them
undercharged, but avoiding heat damage. Then the chargers should
switch to a trickle charge rate in order to complete the charge,
even if it takes several additional hours to finish. For the
charger to fully charge the batteries using the quick charge rate,
they'd have to be charged longer than 2.5 hours, about 3.11 hours at
the 900 ma rate, but the heat generated at the end of the charge
cycle would probably substantially shorten the life of the
batteries. When charging at the much lower 200 ma rate, which isn't
much greater than a trickle charge rate anyway, heat damage won't be
much of a concern.
> By the way, the batteries are NiMH rechargeable (2000 mAh).
Yep, I calculated that and mentioned it in the previous message,
based on the recommended charge rates that you quoted.
> Thanks again, and sorry for not being that clear. I don't know a lot
> about this stuff. Also, if you think I need to buy better batteries or
> whatever, let me know. I plan on using this pretty frequently but
> nothing serious.
You do NOT have to buy better batteries. The best NiMH
rechargeable batteries are currently about 2500 or 2600 mah, and
they'll last longer in your camera, but only about 25% longer. In a
year or two you'll probably be able to buy 3200 mah NiMH cells, and
while they'll last even longer than today's batteries, if 2000man or
2500mah does an adequate job, there's no reason to waste money on
higher capacity batteries. As you use *any* battery, its capacity
will decline with time. In two years, your 2000mah batteries may
provide no better service than new 1600mah batteries would. If you
find that that has you recharging the batteries more often than
you'd like, it might be time to replace the batteries. But if your
batteries, reduced to only 1600mah capacity, last all day on a
single charge (for *your* camera, using your shooting style), then
there won't be an urgent reason to replace them. Only you know will
know when the time will come to replace them, and if you're not
sure, then it probably hasn't reached that time yet . . .