From: ASAAR on
On Wed, 27 Jun 2007 18:26:59 -0700, SMS mendaciously wrote:

>> A low battery warning indicator that works passably well across the
>> different battery types is possible, but forget about a gauge that
>> provides any accurate information. It's like measuring with a
>> micrometer, marking with a crayon, and cutting with an axe.
>
> I added graphs of Li-Ion, NiMH, and Alkaline voltage versus capacity,
> using the same voltage scale (4 packs of AA cells, 7.4V Li-Ion pack).
> This gives a good visual picture of why the AA powered cameras generally
> have only a low-voltage indicator. You'd need so much circuitry and
> intelligence to deal with different battery types that it's impractical
> to implement.

You're only convincing yourself and the gullible. Inexpensive
battery monitoring I.C.s are available for pennies (literally, less
that $1.00) and there isn't even a need to have the owner flip a
mechanical or menu switch to specify whether alkaline or NiMH
batteries are being used in order to gain much greater accuracy.
Many inexpensive chargers have a battery type autodetect function,
to prevent trying to charge alkaline batteries, and that feature
could be easily and inexpensively added to cameras. What would
require limitless circuitry and intelligence is trying to figure out
why you've apparently dedicated your life to deifying Li-Ion
batteries and at the same time fabricating bogus or trivial AA
battery drawbacks to buttress you bias.

From: Ron Hunter on
SMS wrote:
> Ron Hunter wrote:
>
>> I HATE warning lights not accompanied by gauges. The amount of oil
>> pressure needed to prevent engine damage is usually far below the
>> setting for the oil pressure warning light. I could have avoided an
>> expensive tow charge had I had a gauge on my Honda some years ago.
>> Oil pressure is much too important a thing to trust to a stupid 'idiot
>> light'. As it turned out, I COULD have continued to drive the car
>> safely, but without a gauge, I didn't know that.
>
> An ideal addition would be an audible alarm for both temperature and oil
> pressure. My nephew did about $12,000 damage to his four year old BMW X5
> SUV by not heeding the temperature gauge (leaking water pump). Most
> vehicle owners don't have the slightest idea of how an engine is cooled
> or lubricated, or what the gauges mean, but they are used to alarms for
> emergency situations.

I agree that a visual/audible alarm is a good idea, but for those who DO
know something about how the engine actually works, a gauge can provide
much better information than a simple light. My current car can even be
run with a 'total coolant loss' at low speeds as it is able to shut down
cylinders in an alternate pattern and continue to operate at a reduced
speed. NOT something ever want to test, but a handy feature. It is
also the only car I have ever had that has a temperature gauge that is
'active'. That is, it doesn't always just reach a certain temperature,
and stay there, it fluctuates depending on many factors, with the engine
temp controlled by the computer. Rather disconcerting, at first.
Still, that temp gauge DID alert me to a cooling system failure before
anything serious happened to the engine. A leaking intake manifold
gasket was allowing oil into the water, and clogging the system.
From: SMS on
Ron Hunter wrote:

> I agree that a visual/audible alarm is a good idea, but for those who DO
> know something about how the engine actually works, a gauge can provide
> much better information than a simple light.

There's no reason not to have a gauge, a warning light, and an audible
alarm. I think most cars still have a temperature gauge, but how many
people glance at it very often? Most vehicles no longer have an ammeter,
voltage, or oil pressure gauge.

From: ASAAR on
On Thu, 28 Jun 2007 07:16:05 -0700, SMS wrote:

> There's no reason not to have a gauge, a warning light, and an audible
> alarm. I think most cars still have a temperature gauge, but how many
> people glance at it very often? Most vehicles no longer have an ammeter,
> voltage, or oil pressure gauge.

And when the gas tank is replaced with a Li-Ion battery, you'll be
in hog heaven. <g>

From: SMS on
SMS wrote:

> With NiMH, you can know when the batteries are almost exhausted, and
> completely charged, but not know much information in-between, unless you
> go to a test that is more complex than just measuring voltage under
> load. With most NiMH powered cameras, you simply get a low battery
> warning, then maybe a few more pictures, then it shuts down. If they did
> provide a gauge it would be horribly inaccurate if it was based solely
> on voltage.

One more thing that I forgot to mention. The battery gauge ICs rely on
coulomb counting, so the battery must be charged inside the device so
the charge current can be monitored. Also, the self-discharge rate must
be programmed in for the type of battery being used. On "smart
batteries" the gauge will be in the battery pack so batteries can be
swapped and the state of the battery stored in a serial EEPROM. Almost
no NiMH cameras support in camera charging, and the additional
complications of having to deal with replaceable batteries make the use
of a battery gauge IC impractical.

Even with Li-Ion batteries, a coulomb counter is more accurate than
voltage measurement, but at least with Li-Ion the voltage measurement
provides a good estimate of remaining capacity, something that isn't the
case on NiMH. Nikon annoyed some users with the EN-EL3e modification to
the EN-EL3 battery used on earlier cameras, which added a fuel gauge
interface to the battery, and temporarily eliminated after-market
batteries, but they did this to enhance the capability of the camera.