General Laptop AC adapters
Most laptop ac adapters put out 15 Volts to 20 Volts. The ones for more modern laptops usually put out greater than 3 Amps. Older laptop adapters tend to put out 1.5 Amps to 3 Amps. Laptop adapters can put out power up to 6 or 7 Amps.
Sorting AC Adapters
At the laptops station there are drawers under the desk for storing AC adapters, they are sorted by brand plus a bin for everything else. Individual brands have different common tip type/voltage combinations. It is usually only necessary to keep four or five of a given adapter type, above that quantity can be sold.
Any HP or Compaq branded adapter goes in this bin, common ones are 18.5V 3.5A with a small barrel tip. 18.5V under 3.5A with that same tip are for older machines, and can be set aside for sale only.
All apple adapters go in this bin, if they are tested and known good please label them with green tape. The power cord often fails and should not be kept, a standard dog bone cable works with them just fine.
Dell laptop adapters fall into two general types, plus a few more unique types. The common ones are 19.5v 3.34A/4.62A with a large barrel tip and 20v 3.5A/4.5A. It is handy to keep one or two of the 3.x A ones of each type around, they are not used particularly often. The 4.x A of each type should have up to 5 kept, over that number can be sold.
IBM adapters are almost exclusively 16V 3.5A/4.5A. The 3.5A adapters are not worth keeping for our build purposes, there is enough 4.5A to use instead and most newer laptops used 4.5A anyway. Keep 7 or so 4.5A adapters for build use, any 3.5A or 4.5A adapters over the 7 can be sold. Keep 1 or 2 of any other types of IBM adapters.
Toshiba adapters are almost exclusively 15v with a short wide tip. Older Toshiba adapters are 3A or 4A, we do not need any 3A adapters for building, two or three 4A adapters are worth hanging on to, no more. Hold on to 5 or so 5A adapters. There are additionally a few 19V Toshiba adapters all of which should be kept unless there is excessive duplication.
Sony adapters come in 16V and 19V varieties with tip similar to the dell 19.5/4.62 adapters but not compatible. These are fairly rarely used so three or so are all that need to be kept of each type.
The rest of the adapters, like the rest of the bins 5 or so of a given type is sufficient. 19V 4.74A/4.9A are always valuable. 18.5V 3.5A are also quite handy to keep. Adapters under about 3A are not likely to be worth holding on to as they are for to old of laptops for building.