So I wonder if, if you charge several power-hungry devices all on a laptop computer at once (i.e., two smartphones and a Bluetooth headphone; the laptop being plugged into a power socket itself,) if that might surpass the laptop battery’s maximum power-giving ability (whatever that would be called) and fry the laptop’s battery?
Does it consume more power than the battery is meant to disburse at any given moment?
Do laptop batteries have the ability to self-ration/regulate the power they’re feeding out to devices that are eating electricity from them?
no. The battery management won’t let you over-stress the cells. if you’re trying to pull more current than it can safely deliver, the system will likely power down. You might get a warning from the operating system when you get close.
No. In general if the laptop is plugged into the wall, the power to run it is probably coming directly from the wall. It depends on the topology of the laptop’s power converters, it could be setup either way.
Any regulation is from limiters on control circuitry on the laptop’s motherboard. Those smartphones and headsets are being charged by 5 volt DC-DC converters that are fed by a power bus that comes from either the battery or the wall in this scenario. The engineers who designed it would have limited the amperage of those converters to less than what the battery can safely supply.
USB 2.0 ports can only supply 500 mA (2.5 watt). USB 3.0 ports can supply up to 900 mA (4.5 watt), but I believe most phones will only charge at 500 mA from a computer USB port. To charge faster, you need a high current power supply.
Two phones and a bluetooth headset will probably only add up to 6 watt or less. That’s pretty small compared to the power consumption of the laptop itself.
Both are true, but address different issues.
Computers are filled with DC-DC converters. Laptops more than any. These converters nominally convert voltage levels, but they are designed to protect things (including themselves) against delivering or drawing too much current. Batteries need care and feeding. Taking power from a battery to power a laptop requires a multitude of DC-DC converters to come into play to supply power at different voltages and different power requirements to the various components. Any designer will have made sure that the battery is not tasked too hard, and won’t allow these converters to draw more power than the battery can reasonably supply.
The USB ports on any computer are supposed to be current limited, and connected devices are supposed to engage in a little negotiation dance to determine what current they will draw. You see this happen with smart phones - they will draw much more current to charge themselves if they determine that the port is capable of it. However on desktop machines, many motherboard designers where much lazier than you average laptop designer, and they didn’t bother with all the niceties of current negotiation and limiting. They had a big beefy mains driven power supply to hand, so they just connected the USB ports to it (perhaps via a fuse) and let the devices have at it. This has also been true of some laptops - just attach the USB port to the internal 5 volt rail. The 5 volt supply DC-DC converter won’t hurt the battery, but nor will it limit the current the USB device draws - at least not until the converter decides to protect itself.
If the battery is old and has reduced capacity you could. This is the issue Apple hide behind with they getting caught slowing down older iPhones. Apple claims they slowed down phones to forestall this from happening (though there should be no reason to keep them slowed down if the phones were plugged in)
