Can 2 power supplies be connected?

Question

Electronics

Is it possible to connect 2 power supplies from laptops in series to get 40v and what is the risk?

Answer 1

You can do everything, but not everything can be done a second time.
for reliability, at least one power supply must be powered from a 220/220 transformer (galvanic isolation from the network is needed - the autotransformer will not work), otherwise a short circuit through the outlet is possible.
If it is not possible to use a transformer, you should at least check the presence or absence of voltage between the outputs of the power supply unit with a 24v light bulb, if it lights up, you can only connect if there is a transformer. And if it does not light up, this does not guarantee the absence of problems.