These HP power supplies come from the server market and are able to produce a nice 65 amps at 12V. Point is that the 12V minus and the mains ground are connected to the chassis. If you want to put the unit in series you have the isolate the box. This might lead to dangerous situations. It is strongly advised to avoid this and to leave mains GND connected to the box.
If you don’t know what you are doing stay away from this or find suitable help.
Luckily this power supply can be changed easily. The 12V ground is connected via 2 screws to the chassis. A bit of drilling and replacing the 2 PCB connections to the chassis with a plastic (nylon) stand off about 5mm high and a nylon M3 bolt solves this problem.
The following photos show the conversion.
NOTE: The GND is only GND before the modification. It is the – of the 12V supply. If you’re going to put these units in series only one minus can be connected to GND.
