Re: Charging A Lead Acid Battery

On Feb 13, 9:09 am, James Beck <j...@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
In article <6194982a-5fc6-406e-b08d-dd15013ba985
@y5g2000hsf.googlegroups.com>, redbell...@xxxxxxxxx says...

Why is your simple charger so complicated? Why not use a 12 volt DC
wall transformer and 13 ohm resistor (5 watt)? You get 540mA when the
battery is low at 5 volts, and about 400mA as the battery voltage
rises to 7 volts.

-Bill

If you forget to turn off a charger like that, it will seriously
overcharge a 6V battery! On the other hand Ed's charger will not do
that

It won't?
It should continue to charge the battery up to the wall wart voltage,
which is still too high if you leave it plugged in too long.
I would, and do, just use a CV source that is set to the float voltage
of the battery. Pick a regulator that has over temp and current
limiting and let it float.

Jim

What about all the voltage drops between the wall wart and battery:

1 to 1.5V drop-out voltage of regulator
1.2-1.3V between regulator "out" and "adj" pins (across 2.5R resistor)
0.6-0.7V diode drop across 1N400x

Mark
.

Relevant Pages

  • Re: 12 volt power source?
    ... and Greg Procter instead replied: ... A 12 volt battery will never be at a 13.8 volt potential. ... The nominal voltage is the one you want. ... volts safely for long periods of time for keeping the battery ...
    (rec.models.railroad)
  • Re: Outboard Motor Charging System.
    ... >>> Since the terminal voltage of a good lead acid 12 volt battery doesnt ... >>> missing in the description of the voltage. ... >>> terminal voltage might go as high as 17 volts while the battery ...
    (rec.crafts.metalworking)
  • Re: Charging A Lead Acid Battery
    ... battery is low at 5 volts, and about 400mA as the battery voltage ... It should continue to charge the battery up to the wall wart voltage, ...
    (sci.electronics.basics)
  • Re: voltage low on car battery
    ... What is the CHARGING voltage at 2.5 amps after several hours? ... A typical auto battery these days has six cells each, nominally, 2 ... Hence such systems are called 12 volts systems. ... Also one bad cell in the series of six can spoil the battery. ...
    (alt.home.repair)
  • Re: voltage low on car battery
    ... What is the CHARGING voltage at 2.5 amps after several hours? ... A typical auto battery these days has six cells each, nominally, 2 ... Hence such systems are called 12 volts systems. ... Also one bad cell in the series of six can spoil the battery. ...
    (alt.home.repair)