William Sommerwerck wrote:
"mike" wrote in message
...

Here's some empirical evidence.
Power tools have historically had three charge modes.
The cheapest have a trickle charger. People leave 'em on charge all the
time.
The "better" tools have a fast charger with a thermal coutout. The cell
gets HOT and the charge is terminated by the thermal cutout.

The "best" tools have a fast charger that often measures -deltaV for NiCds
or 0delatV for NiMH.

So, here's the experiment.

Go to a garage sale. Almost every garage sale has at least one battery
powered drill.
Have you EVER found a battery powered drill at a garage sale that had a
good battery? I haven't.

If it had a good battery, it wouldn't be at the garage sale.

ba-DUM!

You're letting your desire to be right overshadow your analysis.
How many battery powered drills does the average family need?
When every other garage sale has one, two or even three dead
drills, the statistics are hard to ignore.
The drills are rarely dead. It's almost always the batteries.

Take a design that was intended to be the cheapest initial
purchase cost based on the crappiest batteries available at the time.
Replace the cells with ones having 5x the capacity.
Now, even if the charger design was proper, fast charge termination
is unlikely to be anywhere near correct...as in "never terminates".

Sure, it often works. You feeling lucky?



As I said earlier, I have a Polaroid #365 electronic flash with NiMH
cells
that replaced the original nicads. The #363 rapid charger has no trouble
stopping and switching to trickle charge. It was designed almost 45 years
ago..

The bottom line is that you should always use the EXACT battery chemistry,
type, model number with the charger designed exactly for that battery.

That's no longer possible.

NiMH "behavior" is "close-enough" to nicad that replacement

often

I'm in complete agreement. The only thing we seem to differ on is the
consequences of when it DOESN'T work and if those consequences
are acceptable.


works
well.