Hi, Christian0649!
Thanks for reaching Microsoft Community and posting your concern regarding the 3 different chargers you have for your Surface devices. Kindly visit this page to check the article on Charging your Surface device.
The chargers for your Surface Pro 4, Surface Pro 6, and Surface Laptop 3 have the same connector. So, you can use them on either of the 2 devices you have. You are right, it's the charging speed that will be different. Here is a table of the differences between the 3 chargers you have.
| Power supply unit model # | Surface model | Main charger | USB port on charger | Total wattage |
|---|---|---|---|---|
| 1800 | Surface Pro 6 | 15 volts @ 2.58 amps = 39 watts | 5 volts @ 1 amp = 5 watts | 44 watts |
| 1706 | Surface Laptop 3 | 15 volts @ 4 amps = 60 watts | 5 volts @ 1 amp = 5 watts | 65 watts |
| 1625 | Surface Pro 4 | 12 volts @ 2.58 amps = 31 watts | 5 volts @ 1 amp = 5 watts | 36 watts |
If ever you have a USB-C charger, you can use it on your Surface Laptop 3 as well. Just check out the page I shared for more details on what will work with USB-C charging.
We hope this helps you out, we highly encourage you to inform our Community by clicking on Yes or marking my post as an answer. This will help other members who may have the same issue as you. Otherwise, don't hesitate to update us so we can further assist you.
Kind regards,
Janette_Z