Laptop battery useage

[Ronnie Gauthier]

On Sat, 03 Jun 2006 07:21:39 -0600
"Michael Hipp" <michael at hipp.com> wrote:

> > From: "Ronnie Gauthier" <ronnieg at chartermi.net>
> > "Michael Hipp" <michael at hipp.com> wrote:
> > > Generally on Nicad and NiMH batteries it is best to do a full discharge 
> > > once and a while. Helps prevent that so-called "memory effect".
> > 
> > Have you ever seen a battery take a memory set outside of an industrial 
> > setting?
> 
> Yes. Frequently. Almost predictably. The old Nicads were especially bad about this, NiMH seems quite a bit more forgiving.
> 

I would think that was just the effect of an old battery losing output 
capability or a severly mistreated battery. Storing a near dead battery 
or leaving a battery in a charger past its fill will kill even a new
battery in short order. Yet its common practice for people to plug them 
into a charger and leave them overnight. Batteries then get far to hot and
the life expectancy is shot. Get in that habit and you will most likely 
need a new battery every 6 mos to a year. Almost every charger for home 
use does not stop charging when the battery is full but just keeps on 
charging and the battery gets hotter and hotter. Another problem is 
under-charging. Everyone is in a hurry and when they have enough charge 
to get going they stop and are on their way, happily using whatever and 
not even knowing they are killing their battery.

> > Not likely. Here's why. To take a memory set a battery needs to be 
> > discharged to
> > the same level each time and then recharged to the same level. After repeated
> > cycles of this the battery gets lazy and only uses from the discharge level
> > to the charge level. This usually happens when someone makes their own 
> > automatic
> > charging system and the bottom control and the top control are hard set and 
> > not
> > random within a range.
> 
> I won't pretend to be any kind of expert on battery chemistry, but this does not jibe with the emperical data. Especially on Nicads, the memory effect will begin to show itself after only a few cycles of incomplete discharge. (Born simply of a desire to not let the batteries run down on that beloved cell phone, laptop, music player.) The same is true of NiMH but to a lesser degree.
> 
> I don't know anyone that's built their own automatic charger. Well, other than that industrial charger manufacturer that I wrote all that embedded PICmicro code for a few years ago. Most of those batteries were gel or liquid lead-acid.
>
> > If a Ni battery is overcharged you in effect "recondition" the battery.
> 
> NIcad or NImh? I've always heard this but never been able to make it work in the real world. The only way to recondition them was in the trash can (er, recycle bin) :-)
>

NiCd are more prone to problems associated with discharge/charge cycles than
MiMH but both are sensitive to over-charging. The reconditioning is actually 
just a draining and a super fast quick charge.

If you were a manufacturer would you design a home charger to allow a super
fast charge? They can get very hot and must be controlled, not like 90% of
home users would do, plug it in and check it in the morning. Problem
is it would explode long before morning. Not to mention that you have to 
pay to have a battery zapped, reconditioning is a huge business.

Good page for info, http://www.ciwmb.ca.gov/WPW/Power/RechBattInfo.htm

Ronnie