Laptop battery useage

[Alma J Wetzker]

Ronnie Gauthier wrote:
> On Sat, 3 Jun 2006 10:50:26 -0400
> Bruce Marshall <bmarsh at bmarsh.com> wrote:
>>On Saturday 03 June 2006 09:21, Michael Hipp 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.
>>
>>This report says they couldn't reproduce a memory effect in a test.
>>
>>http://www.repairfaq.org/ELE/F_NiCd_Memory.html
>>
>>This report says memory effect is a big problem....
>>
>>http://www.zbattery.com/memoryeffect.html
>>
> 
> I think they say the same thing. It not a memory problem but a user caused problem
> related to charging habits. Just exactly what I have been trying to stress. It's
> all how you treat your battery that determines it useful life span.

Let us please go back to the science.  A battery is a chemical reaction 
that moves anions (-) to one terminal and cations (+) to the other 
terminal.  In a rechargeable battery, the reaction is reversible.  The 
reaction to recharge the battery involves heat, usually generating a set 
amount, if you recharge fast, all that heat is generated at once.

Every battery charger that I have seen in the past decade or so has a 
trickle charge mode.  That means that once the battery is fully charged, 
only a minuscule amount of power is put into the battery, to counter the 
normal loss due to entropy as it sits on a shelf.  Trickle chargers are 
simple and have been well known since the 1980's.

Battery memory is caused by incomplete charge/discharge cycles where you 
start to get metal bridging (the anion) making little wires that short 
the battery terminals at a certain power level.  (Remember that the 
charge/discharge cause the metal atoms to move from one pole to the 
other.)  The way to recondition the battery is to apply a very short 
burst of power in the REVERSE polarity.  That treats the little wires as 
fuses, that you melt away.  NiCads have well known memory problems, NiMH 
have reports both ways, but it is still not as bad as NiCads, by a wide 
margin.  The battery does not need to be discharged to the same level to 
develop memory, it just needs to be incompletely discharged.  The 
battery memory will develop at the "average" discharge level.

LiIon should not have memory, but they are more heat sensitive and can 
only be charged (from any level) a set number of times (about 1000). 
Remember that heat can affect the efficiency of the chemical reaction, 
usually adversely

This is all theoretical stuff from my class that covered batteries a few 
semesters back.  It may not be 100%, but is should be very close.  There 
is quite a bit of mystic tradition about how batteries should be 
treated, that really make little sense.

Bottom line:
1.  If your batteries are operating at temps too hot for skin, that is bad.
2.  Make sure that your battery charger has a trickle charge mode.  All 
laptops that I am aware of back to the 286 Compaqs have this.
3.  Discharge Ni?? batteries completely occasionally (monthly?)  The 
only drawback operating Li?? batteries from a partial charge is that you 
lose a recharge without fully using it.  (About like paying for 
something and leaving without your change.)

     -- Alma