On Tue, 18 Mar 2008 10:07:45 +0700, Bruce in Bangkok wrote:
....
While there is no question that high voltage will damage a battery, in
real life most battery chargers will be perfectly suitable since a
battery's internal resistance increases as the battery is charged making
the system is pretty much self limiting.

Internal resistance vs. charge depends a bit on battery type and
history. [1][2] For lead-acid batteries, internal resistance
decreases (not increases) as charge goes up. For typical car
battery chargers, current drops as charge approaches 100% because
the difference between charger voltage and battery voltage drops
toward zero. Open-circuit charger voltage and charger resistance
will be the main limiting factors.

Try connecting a volt meter and an amp meter in parallel with the
battery charger. Turn the charger up to about a 10 amps charging current
and watch the volt meter. As voltage climbs the amperage decreases. With
about a 10 amp initial charging current by the time the battery voltage
reaches about 13.5 volts the current will have decreased to about 1 or 2
amps. Hardly a battery killing combination.
....

[1] http://www.arttec.net/Solar_Mower/4_...20Charging.pdf
in section "Lead-acid Internal Resistance and SOC" at bottom of 4th page
says "A fully discharged lead-acid cell has virtually no sulfuric
acid in its almost pure water electrolyte" [so would have high resistance]

[2] Near end of http://www.batteryuniversity.com/partone-22.htm ,
the paragraph before Figure 6 (resistance vs. voltage) says
"The resistance of lead acid goes up with discharge", etc.
-jiw