moderator pls help me w/ this., it possible to connect a diode at positive/negative side of the output to prevent the current from battery entering the circuit? if yes is there any effect to the circuit? thanks in advance
man ofcourse u can't cz this circuit needs to test the voltage on the battery so if u used a diode ull prevent that from happening so Q2 will never turn on
That's only partially true. With a diode fitted the circuit will see 0V battery volts so it will assume the battery is flat and switch on the charger. Once the circuit is charging and the diode is conducting then it will 'see' battery volts plus 0.7V.
All you need to do is set up the potentiometer to give a charger output 0.7V higher than without the diode.
another question.., i have a NiCd and NiMH batteries and it's require a 12V charger to charge it, so its possible that i can use this 12V Lead Battery Charger to charge my NiCd and NiMH batteries? thank's in advance
Ni-Cad and Ni-MH batteries need a completely different charger circuit from the lead-acid battery charger.
Usually a regulated current is used and the small voltage peak-dip is sensed or the rapid rise in battery temperature is sensed to stop the charging when the battery is fully charged. ICs are made to charge these batteries.
A 12V Ni-Cad or Ni-MH battery is fully charged at 14.0V to 15.0V depending on the charging current. Maxim-IC have some battery charger ICs and the schematic for the battery charger is in their datasheets.
The charger circuits are automatic to charge quickly but avoid the battery exploding if it is overcharged.
Why should resitors R4,R5,R7 and R8 be of high wattage yet they send current to the gate and the gate draws little current and also why are they four in number cant two of them of 2watts connected in series serve the purpose? Also these resistors are always very hot why is this? Thanks Dennis