2 19VDC laptop chargers in series

[Al Skierkiewicz]

Guys,
I would really like to get a handle on this discussion. It is OK to add power supplies in series. It is not OK to add battery chargers in series. Luckily I believe we are talking power supplies. Current flow will will be supplied by both power modules and since they are in series there is no need to add anything to smooth or share current flow. It will occur naturally. Ether, I am going to guess you did not measure low resistance from the third pin to both outputs. Likely what you measured were output protection devices like MOVs or some other device meant to keep ESD spikes to a minimum. As long as the resistance was a couple of kohms you are fine. Good practice would suggest that the three pin supply provide ground to the circuit you are powering and the two pin supply provide the higher voltage. Since the two pin supply has no continuity to primary wiring, connecting it as the higher supply should be just fine. As additional protection, a fuse in one leg of each supply might be a good idea in case something should happen with one supply, it would isolate the fault from damaging the other supply.