Question about laptop

[Jane]

f I connect a charger, to a laptop ,  must the  laptop start if battery is flat ( or disconnected) and charging circuit is damaged? Or the  working charging circuit is necessary for a laptop to start?

[Zero999]

f I connect a charger, to a laptop ,  must the  laptop start if battery is flat ( or disconnected) and charging circuit is damaged? Or the  working charging circuit is necessary for a laptop to start?

No, the battery doesn't have to be flat. The charging circuit in the laptop will only charge the battery, if it needs to be charged. The laptop will be happy connected to the mains power supply, whether the battery is fully charged, or flat.

If there is a fault with the charging circuit, the battery will most likely not charge. There is a risk it could overcharge, in which case, the battery should have a protection circuit, to prevent fire and leakage. Some laptops won't work without a battery, which indicates the battery charging circuitary is part of the internal power supply. If you suspect the laptop's internal battery charging circuitary is faulty, you shouldn't attempt to charge the battery with it.

[Jane]

Thanks for your reply.
But not sure I fully understand

No, the battery doesn't have to be flat. The charging circuit in the laptop will only charge the battery, if it needs to be charged. The laptop will be happy connected to the mains power supply, whether the battery is fully charged, or flat.

So if I connect power supply and laptop is without battery, the laptot usually starts. But is working charging circuit necessary  for a laptop to start without battery?

[BravoV]

Laptop will work with and without the battery.

And if the laptop is turned on without the battery, powered from the adaptor of course, it wont damage the charging circuitry, with or without the battery (full,partial or dead flat).

This assuming the laptop is the one with detachable battery designed from manufacturer.

[PKTKS]

Well .....   that depends on the circuits itself..

and they  do vary a lot across  age, manuf., model..

I have seen more recent models with "devices"
in the schematics I can not readily recognize..

Some symbols that hopefully implement some
better (hopefully)  logic in the charging port
and prevent damaged things to go weird.

Fortunately these "new" symbols (devices)  mostly
come with some code hint to try (i said try) to spot
their datasheet..

Although each day I find myself spending more time
trying so

Paul