Rechargeable Battery Problem

Joseph Meehan wrote:

As I said, using the definition of "smart charger" that you choose to
use then I have to divide them into too groups. Those that are more
intelligent and those that are ... intelligence challenged.

Yes - some smart chargers do a better job than others. That being
said, battery industry marketing (not me) has chosen to define
"smart/intelligent charger" as one that shuts off when it senses
a full charge, regardless of whether it has charging circuits that
work on 1,2,3, or 4 cells.

Simple fact. It is far better to charge and monitor each cell (not
groups of cells) independently. Sometimes cells are mixed and even if they
are not they are not going to end up with exactly the same
charge/discharge/capacity so we try to customize the charge for each one.

I don't disagree with that. However - fewer charging circuits means
simpler design and lower costs (I say this as an engineer). That
coupled with the fact that most people use 2/4 cell devices makes
chargers that only work with pairs an option with consumers. Smart
charging circuits in the newer hybrid cars charge over 100 cells as
a single unit. It would be impractical and cost prohibitive to
wire/charge/monitor each cell individually.

Some chargers have even stranger permutations. My Sony charger
(2 charging circuits) charges 2 cells at 1000 mA, but 4 cells at
500 mA.

There are certainly dumb charging circuits. Check any cordless
phone with a 3-cell battery pack. They're simply charged with a
low current when the handset is in the cradle.

I may be wrong, but I believe most people understand that a smart
charger is one that is smart enough to adjust for each cell. Maybe we
should classify the chargers you are talking about as almost smart. ;-)

Do you have some official reference defining smart charger?

You're not going to find one, because the language is primarily
driven by marketing types. I did find site that said "modern
intelligent chargers" worked on each cell individually. However -
I've understood "smart charger" to be one with what's known as a
processor-controlled "Delta-V" mechanism. As far as I can tell,
all this means is that it's given a charging pulse, shut off,
monitored for voltage, and the process is repeated until the
voltage reaches a cutoff point. This mechanism can be used for
charging any number of cells in series.

One site refers to individual charging as 'individual supervision'.

http://www.digibattery.co.uk/nimh_charger_faqs.htm

I expect the manufacturers to latch onto the term so they can confuse
the customers into buying their not-so-smart charger thinking it was a true
smart charger, but I would hope that we would be more particular and careful
about how we describe something.

Regardless - the Maha chargers that work only with pairs have been
highly regarded in this group. While they're not ideal, I'd choose a
well designed delta-V charger that takes two/four cells (like a Maha)
over a less than ideal charger that works on each one independently
(like my Rayovac chargers). I've had one Rayovac PS1 seriously
overcharge batteries (where they leaked), and it was replaced with a
PS3. It's not bad, but I'd trust a 2/4 cell Maha charger over it any
day.

"y_p_w" wrote in message
ink.net...


snip
Do you have some official reference defining smart charger?

You're not going to find one, because the language is primarily
driven by marketing types. I did find site that said "modern
intelligent chargers" worked on each cell individually. However -
I've understood "smart charger" to be one with what's known as a
processor-controlled "Delta-V" mechanism. As far as I can tell,
all this means is that it's given a charging pulse, shut off,
monitored for voltage, and the process is repeated until the
voltage reaches a cutoff point. This mechanism can be used for
charging any number of cells in series.

Use an Ansmann Powerline charger .. 4 AA or AAA cels (one can mix) charge
1-2-3-4 independently .. dV/dT shutoff .. never fails :-)

"Joseph Meehan" wrote in
:


Do you have some official reference defining smart charger?

http://www.panasonic.com/industrial/...Panasonic_NiMH
_ChargeMethods.pdf


I expect the manufacturers to latch onto the term so they can
confuse
the customers into buying their not-so-smart charger thinking it was a
true smart charger, but I would hope that we would be more particular
and careful about how we describe something.



Here's a smart charger that charges a string of 20 cells:

http://www.batteryspace.com/index.as...ROD&ProdID=387

Tim

--

"The strongest human instinct is to impart information,
and the second strongest is to resist it."

Kenneth Graham

"Joseph Meehan" wrote in
:


Do you have some official reference defining smart charger?

http://www.panasonic.com/industrial/...Panasonic_NiMH
_ChargeMethods.pdf


I expect the manufacturers to latch onto the term so they can
confuse
the customers into buying their not-so-smart charger thinking it was a
true smart charger, but I would hope that we would be more particular
and careful about how we describe something.



Here's a smart charger that charges a string of 20 cells:

http://www.batteryspace.com/index.as...ROD&ProdID=387

Tim

--

"The strongest human instinct is to impart information,
and the second strongest is to resist it."

Kenneth Graham

"Joseph Meehan" wrote in
:


Do you have some official reference defining smart charger?

http://www.panasonic.com/industrial/...Panasonic_NiMH
_ChargeMethods.pdf


I expect the manufacturers to latch onto the term so they can
confuse
the customers into buying their not-so-smart charger thinking it was a
true smart charger, but I would hope that we would be more particular
and careful about how we describe something.



Here's a smart charger that charges a string of 20 cells:

http://www.batteryspace.com/index.as...ROD&ProdID=387

Tim

--

"The strongest human instinct is to impart information,
and the second strongest is to resist it."

Kenneth Graham