Re: Whatever happened to fast-charge batteries? What about Hybrid NiMH?

ASAAR wrote:
On Tue, 28 Aug 2007 06:41:45 GMT, mike wrote:

Last few weeks I've picked up some AA battery chargers at garage sales.
got a 30 minute one, a 15 minute one and a 8.5 minute one.
Went looking for batteries and can't find any in the local stores.
Is the 15 minutes of fame over on fast charge batteries?

I've seen 15 minute chargers on racks in several stores recently
but haven't looked to see if any "fast charge" batteries were also
being sold. But that shouldn't be a problem, because as far as I
know, only the old RayOVac 15 minute chargers required special "15
minute" NiMH batteries. Their "15 minute" chargers, btw, reverted
to an extremely slow, near trickle charge rate with any other
batteries. Other brand 15 minute chargers should work with any of
the recent high capacity NiMH batteries. If you have a local
Rite-Aid, it may have the 15-minute Duracell chargers that I saw on
display, possibly Walgreens as well, and the included batteries are
visible in the unopened packages, which should let you see they use
standard NiMH batteries.

I never heard of an 8.5 minute charger though. I've seen some mp3
players (Sony) that advertise using a Li-Ion battery that can get a
significant charge in only a few minutes, for people with not enough
time to wait for the much longer amount of time for a full charge.


I found zero information on the Sakar CH-7900 8.5 minute charger. Lots of
google hits, but all copies of the same press release. Product has been
discontinued.
From the Sakar site, came this jewel:
"Fully compatible lithium ion battery.
Meets or exceeds all manufacturers’ specifications.
This product has been fully tested by the institute
of bench marking excellence
to perform at the highest standards."

Wrong battery technology, but at least it has been
tested by the...WTF?

I tried charging an ordinary NiMH battery with it. It does
indeed stuff 8.5 Amps into the cell. No obvioius current
interruption to measure stuff. Had to terminate the test
after a few seconds because my current measuring loop
started to melt.

There is a thermistor in the negative contact, but I don't
think ordinary batteries will heat up enough before they vent.
Not surprised the product was discontinued. No special batteries,
you got a doorstop. But came with a nice 12V 3.5A wall wart...
so the 25-cents wasn't wasted.

The 15minute RayOVac PS6 pulses 1Amp with 5% duty factor.
Has a sensor that senses the resistance of a band on the
high rate batteries. No 15-minute batteries...you got a doorstop.
But it came with a nice 14.5V 4.5A wall wart...so the 25-cents wasn't wasted.

The 30-minute Duracell CEF90NC charger appears to be making some measurements.
It stuffs almost 4 amps into the cell, but interrupts every two seconds or so. Also seems to be doing some current steps...assume they're measuring resistance or something. Most of my random collection of
cells it won't charge. But for the ones it accepts, it seems to do
a reasonable job without overheating. Some of the cells I experimented on seem to have a higher than normal self-discharge rate. Maybe
caused by the charger, but the experiment was largely uncontrolled.
When I inquired of Duracell about a manual, there is none. Guess it's so
foolproof that you don't need one.

The 1-hour Duracell CEF12N charger also seems to be doing some measurements.
Won't charge some of my random cells, but does a good job on the ones
that it does. Cells get hotter than the 30-minute one because it doesn't have a fan.

I'm pretty happy with the Duracell chargers. They'll charge an odd
number of cells which most of my devices use.

I'm not really interested in fast charging batteries. Just fell into
some really cheap chargers.

My current interest is the new hybrid NiMH cells that claim to retain
their charge for a year. I've had a set in a digital camera for six months. Every time I pick up the camera to take a picture...it works.
With the old-style NiMH, the camera was always dead. With these,
I get ample warning so I can take a bunch more shots and recharge
at my leisure.

Anybody got any experience with 1-hour charging Hybrid NiMH cells?
The charger that came with 'em charges in pairs. But my mp3 player
uses one. I'm afraid to put them in the 1-hour charger and mess
up the excellent charge retention by overheating them.

Experiences?
Thanks, mike

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