• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

battery charger circuit for 9v pp3 battery anyone ?

Not open for further replies.


New Member
Hi all,

I've seen loads of charger circuits for AA type batterys but see nothing decent around for a 9v pp3 battery. I'm after a simple charger schematic that will fully discharge a pp3, then charge it to maximim capacity then trickle charge.

I use these batterys for my radio guitar pack, so i need to know they are charged fully before hitting the stage !

Cheers :)


Well-Known Member
Most Helpful Member
For the nOObs who are reading this old but renewed thread, you must NEVER fully discharge a rechargeable battery.
Each cell of an old Ni-Cad battery work best when fully discharged (separately) but modern Ni-MH cells do not.

If you discharge a battery too low then the weakest cell gets to 0V first and the current in the remaining cells charge it BACKWARDS which damages it.
The battery should have its load disconnected when the average voltage of each cell is 1.0V or 1.1V.

An old "9V" Ni-Cad rechargeable "9V" battery is not 9V, it is nominally only 7.2V because it has six 1.2V cells in series. Modern Ni-MH "9V" batteries are nominally 8.4V because they have seven 1.2V cells in series.
Not open for further replies.

Latest threads

EE World Online Articles