I buy an used notebook (Sony Vaio SVF152C29X), its only defect is that it doesn't charge the battery, it only works plugged in the power supply (19.5V and 6.2A output).
I don't know if the battery doesn't charge because it's dead or if it is a notebook defect.
I used a multimeter (in DCV position) to measure the output in the notebook terminal (where I plug the battery) and it shows 19V. But the battery specification is 14.8V/2670mAh/40W (it is a Sony VGP-BPS35A).
Is there something wrong with the notebook or it do exists batteries 14.8V that charges with 19V voltage? Or the battery can have a smaller transformer inside it?
Best Answer
There must be 1 step down converter with current and voltage control for the battery pack ( which is most likely dead or very weak) and then many step down regulators for the motherboard for CPU, GPU, RAM, I/O. So the 19V is just a universal charger + mobo driver voltage and you're just reading the voltage just stored by the charger there recently, which you ought to be able to pull down with xx K resistor as it ought to be reverse current diode protected.