This is a simple 12V Lead Acid Battery Desultorily Circuit Diagram. Lead acid batteries often fail prematurely due to over-charging,
under-charging, deep discharging and low electrolyte level. All of these
can lead to sulphation of the plates which leads to high internal
resistance and eventual failure. Normally, this process is regarded as
irreversible but this circuit is claimed to reverse the process by
applying high voltage pulses to break down the lead sulphate compounds.
The circuit is essentially a high-voltage pulse generator which is
powered directly from the battery in question. If the battery is badly
sulphated, it will be necessary to connect it to a low power charger as
well, say 2A. We have strong doubts about whether battery sulphation can
be effectively reversed but we are publishing this circuit because the
subject is of particular interest.
This circuit has been submitted to us from a number of sources so we do
not know who is the original designer. More information can be found at http://shaka.com/~kalepa/desulf.
The 555 timer is connected as an astable oscillator with its output
frequency set by R1, R2 and C2. Its output pulses drive the gate of
Mosfet Q1 which turns on to charge inductors L1 and L2. At the end of
each pulse, Q1 turns off and the inductors develop a high-voltage
high-current pulse which is applied across the battery via fast recovery
diode D1 and the 100µF capacitor. The 555 is protected from the high
voltage pulses via its isolated supply, by virtue of the 15V zener diode
ZD1, the 47µF capacitor and the 330Oresistor R3.
Author: Silicon Chip – Copyright: Silicon Chip Electronics Magazine
