A laptop is designed to be portable, which is why a laptop has an internal battery. Laptops can also be powered using a cable plugged into the mains. This power cable is also used to recharge the battery. One advantage of the internal battery in a laptop is, if there is a sudden power outage, the battery will continue to power the laptop until the battery runs down. In a power outage, a desktop computer would simply stop working.
The normal power back up would be a battery. Some may come with a back up battery pack already built it. Other's you may need to buy one for and have it professionally installed.
NO! where does the power (voltage and current) come from if the battery is flat/dead?
No. If the alternator is working fine, the battery power is not used.
because the battery is the source of the power for the headlights. there could be an issue with the battery or the alternator can be failing.
battery and coil
New batteries almost always come fully charged. If it was not then charge it with a battery charger and do not use your vehicle alternator to charge a dead battery. You may do harm to the alternator which is not built to charge a dead battery but is instead built to keep a good battery fully charged.
Have you tested the battery to see if it has power in it? If it has have you made sure the contacts are good? If they are is there a fuse that has blown.
Yes, otherwise it will be useless when the battery runs out.
Yes, but there may not be enough power to start the engine.
You are having fan belt problems.
All laptops come equipped with their own battery packs. When you disconnect a laptop from the mains, it automatically switches to the DC power from its battery pack.
Check your fan/accessory/serpentine belt.