New Slim 65W Dell Charger Replacement HF991 19.5V 3.34A PA-2E Family
Compared to laptop battery, AC adapter HF991 has more complex internal circuits, transformer in particular. First of all, it has achieved voltage filter on the new coming input voltage to ensure the power supply can be kept in a stable good condition. And then the voltage after stabilization will be divided into two parts, one for notebook computer and another for lithium-ion battery. As a matter of fact, these two devices have different receiving mode. Comparatively, the motherboard has simpler work principle and battery has to be examined and gone through the protection circuits before the energy reach the lithium-ion cells. That is why usually, 19.5V HF991 laptop charger output voltage is higher than those Inspiron and XPS batteries as the remaining voltage is prepared for the protection circuit. So please be easy with this 65W AC adapter for Dell. The final power energy, voltage and current that reach the laptop battery are just accurately set according to what the cells need.