USB C trickle charging a laptop?

[david151]

Many laptops now have the ability to charge by usb C, but many of these seem quite strict in their requirements. For example I believe the Dell XPS 13 still needs around 20V at 3A (even when off) or it refuses to charge. I believe the Macbook also requires relatively high power before before the charging circuit kicks in.

Does anyone know if there are any laptops that support the ability to trickle charge from much lower power sources e.g. small phone chargers? Granted it will take a long time to charge, but I want to know if any of them make this possible?

From my research I believe the Google Chromebook Pixel can accept a trickle charge from a low powered device. Does anyone know of any other laptops?

 

[XavierMace]

I would suspect the requirement is due to the fact that most devices don't actually completely shutdown these days. It's just in a low power sleep mode. Therefore the charger would need to have at least enough power to offset the sleep usage plus some extra to actually charge it. For example I know I have a car charger that struggles to charge my Galaxy Tab S2 even with the screen off.

 

[bryanl]

Lithium-ion batteries can be charged slowly but cannot be trickle charged because overcharge is not tolerated virtually at all. Any charging mechanism must sense full charge and shut off completely.