Desulphater for Car Batteries

Even if you take great care of your car or motorbike battery, you're bound to have noticed that its life is considerably shorter than the high purchase price and sales pitch probably led you to expect. Of course there are several reasons for this, and high on the list is the phenomenon of slow but inevitable sulphating of the plates. Here' a circuit to prevent as well as combat sulphation.

R1 = 470kΩ
R2 = 22kΩ
R3 = 330Ω
R4 = 220Ω
Capacitors
C1 = 100μF 25 V
C2 = 100nF
C3 = 2nF2
C4 = 47nF
C5 = 100μF 25 V, low ESR
Semiconductors
D1 = 15 V 0.4 W zener diode
D2 = BYW29-100
IC1 = NE555
T1 = IRF9540
Inductors
L1 = 220μF 3.5A
L1 = 1mH 1A