[Novalug] Laptop Battery

Bryan J Smith b.j.smith@ieee.org
Thu Nov 12 09:31:35 EST 2009


[ I'm going to answer all future posts off-line after this one. ]

On Thu, 2009-11-12 at 01:30 -0500, John Franklin wrote:

> A matter of definitions.  A battery marketed as a "six-cell,
> self-maintatining battery" could be either:
> a) a six-cell battery that defines a "full charge" as five full cells,
> OR
> b) a seven cell battery that guarantees at least six full cells as a
> "full charge."

Again, I'm not following this logic at all.  It doesn't provide any
benefits except the negative, "less charge" than possible, with _no_,
additional longevity.  Individual Lithium-Ion cells have their own,
individual longevity issue.  So any combinational changes of the entire
circuit have no effect on that longevity.

SIDE NOTE:  You're also failing power 101 here.  How do I put a 7th
3.6-3.7V battery for the typical 6-cell, 12V output (14V input/charge)?
I.e., 6-cell is 2x3 -- 2 parallel circuits of 3 x 3.6-3.7V batteries in
series?  9-cell gives you 3 parallel circuits, with more real-time
current and longevity.

There's really no way to have a "spare battery" without unnecessary
switching complexity (that you absolutely don't want) that, again, does
absolutely nothing when it comes to individual battery cell life.

> After all, other engineered items define 100% as less than full.
> Formatted drives reserve 5% for root, bridges (for cars and
> pedestrians) are certified for weights below their real breaking
> point.

Apples and oranges.

What you are talking about with disks would -- to make an analogy --
have absolutely no impact on the longevity of individual NAND EEPROM
cells as well.  There are so many individual writes that NAND cell
blocks can sustain, just like charges of individual Li-Ion cells.

> So, why can't a six cell battery be considered "full" when 5 cells out
> of 6 are at 100%?

It means you'd just get less battery charge for the same volume.  I
don't see how this logic helps the situation at all.  ;)

> The battery is a lot smarter than I am when it comes to maintaining
> peak battery efficiency.  Why should tending to the battery be *my*
> problem?

It's chemical properties.  Nickel has its.  Lithium has its.

> I don't choose the cylinder group to allocate the next inodes.

However, if you _do_ take the time to optimize your cylinder alignment
when you manage volumes and filesystems, you _can_ get better
performance.

Same deal with battery materials.  Understanding their lifecycle
improves longevity.

> I don't choose which memory gets swapped out.

But you _can_ optimize it as well!  ;)

>  The batteries, which already have software (firmware) running, can
> manage this much better than I, a dumb user, ever could.

They already do, especially Li-Ion.  But there are some properties of
the material that still require you to use it optimally as you discharge
and recharge.  Again, I haven't heard a single recommendation here that
does anything.  That's why I'm confused and not following you.


-- 
Bryan J  Smith         Professional, Technical Annoyance 
Linked Profile:       http://www.linkedin.com/in/bjsmith 
-------------------------------------------------------- 
Only engineers can solve the growing needs of consumers
Stop being "aware" (that's so '70s) and start supporting
real solutions that actually work and sustain the planet






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