Re: Battery Management

[Paul Stenquist]

I have a lot of experience with nicads from the days when my son and I 
raced electric radio control cars. Slow charging would give you maximum 
run time. However, fast charging delivered maximum amperage, which is 
what we were after. We charged at 6 amps until the battery voltage 
peaked. Then just before setting the car down on the track, we would 
peak the batteries once more. We kept a cooling fan on them all the 
time, but they still got very warm. Some of the very serious 
factory-backed racers used to go to the starting line with a push cart 
that held their battery charger and power supply. They would keep the 
charger in place until the last possible second. After a race, the 
batteries would be connected to a device that virtually shorted them 
out. It provided about 1.5 ohm resistance on a dead short circuit. This 
drained the batteries in seconds. This device was also used to 
condition new batteries, to "teach" them to discharge quickly at very 
high amperage. Those factory racers would sometimes discard a set of 
batteries after only a few five minute races, because they lost their 
ability to deliver peak voltage and high amperage in a hurry.  It 
wasn't unusual to cause cells to vent while charging. After that, they 
were toast. There was one series where maximum run time was important 
because the heats were longer. For that kind of racing, slow overnight 
trickle charging was the order of the day. I don't know if any of this 
applies to nimh batteries, but I slow charge mine.
Paul
On Apr 10, 2005, at 10:52 AM, Shel Belinkoff wrote:

Mark,
I don't know squat about batteries, especially these newer types, 
however,
I recall reading somewhere that rapidly charging a battery is not the 
ideal
way to recharge, and that doing so can shorten battery life.  IAC, it's
always been my impression that a slower charge is better for 
longevity.  I
just wonder if there's any truth to that, or if there ever was.

That said, the rechargeable lithium ion bats that are in the various 
Sony
cameras that I've used have lasted a very long time .... years, 
actually.
The bat on my first camera lasted three or four years before finally
getting to the point where it wouldn't hold a charge for a long time, 
and
the bats in my current Sony, which are at least two years old, are 
still
going strong.  In both instances the charging process used is on the 
slow
side, taking about four hours or so to fully recharge.

Shel

[Original Message]
From: Mark Cassino

From: "Alan P. Hayes"
I get the impression that a lot of what people describe as memory
problems
are really just out and out battery damage due to overheating and
probably
other stuff.
....
I have an Energizer 30 minute charger. The batteries are HOT when they
come
out - they won't physically burn your fingers, but they are too hot to
comfortably hold in your hand.
I bought this a couple of years ago to replace an older Rayovac 
charger
that
took about 8 hours to charge up a set of NMHi batteries. Unfortunately
the
Rayovac was damaged when a battery leaked inside of it.
I've been tossing NiHI that are in the 3 year old range - they won't 
take
a
charge from the energizer charger. It's hard to say how much use they 
get
since they have been used in the *ist-D, CoolPix 990, and lots of
flashes.
But could the high temps of the charger be a problem?