Battery charger & indicator circuit

[rajrocks]

Hello again

I got three old type SUNCA sealed lead acid rechargeable batteries each of 4v 1.0Ah & 1 Amp

voltage regulation
Cycle use : 5.00v-5.20v
Standby use : 4.70v-4.90v
maximum charging current : 0.21A

Now i am combining all the three in series so as to get a net of 12volts

So i want to design a proper charging circuit diagram containing easily available components

Again i want to make an indicator circuit for the combination to indicate

1) over discgarge
2) normal discharge
3) full charge

please help sir