Question regarding Laptop charging using cordless electricity

[arto]

Hello!
Sorry if this is the wrong folder - my first post up here.

I have a laptop which eats 19V 4,74A (90W max). Let's say I have a wireless power transfer system which can deliver up to 100W (19V 5,26A). When I try to power up the laptop from bench power supply, the current fluctuates constantly from about 1,5 to 3,5A depending on the laptop CPU load. The problem is that my power transfer system resets/stops working every time there is this rapid current change (due to safety mechanisms), though it works perfectly in CC mode or when the laptop is being charged when turned off (with current at around 1.5A). Same issues with 70W rated laptop.
I was wondering if there is any way to stabilize the current between my system and the laptop - since it could easy charge with 4.74A as long as it is constant current.

Thank you!

[amyk]

A big capacitor.

[arto]

Thanks!
But will it actually drop even more power or how big should it be?
Or is there any other solution?

[Kjelt]

Obviously your labsupply is not the right tool for this load.
Why not spent $25 on a compatible laptop PS? Or if your laptop does not have the difficult three pin dc jacks (communicating with the PS about the power like Dell and HP) you can buy any second hand laptop PS , going for $10 on ebay

[arto]

Thanks!
The problem is not with the lab supply - it works fine, I just use it to see the load current behavior. The problem is that my wireless power transfer system can supply enough power for laptop but only when the current is stable. In this case, as I mentioned, the laptop draws  1,5 to 3,5A  which fluctuates according to CPU load.

[tszaboo]

Thanks!
The problem is not with the lab supply - it works fine, I just use it to see the load current behavior. The problem is that my wireless power transfer system can supply enough power for laptop but only when the current is stable. In this case, as I mentioned, the laptop draws  1,5 to 3,5A  which fluctuates according to CPU load.

How much is the coupling between the wireless chargers?
I saw mobile chargers having "glorious" up to 0.5-0.7 coupling...

[arto]

Any other ideas? Anyone?

[Richard Crowley]

Any other ideas? Anyone?

You haven't really given us any useful information to work with, only symptoms.
The best we can do is to advise you to go back to the drawing board and invent a more stable scheme.