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| Can power supplies be linked together like batteries for higher voltages/amps? |
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| ArthurDent:
As others have said, unless you absolutely know that the output of a power supply is designed to be floated or put in series/parallel, assume that it can only be used the way it was in the original application. There are some supplies that are designed to be floated but these are generally higher end supplies and it will say, either near the terminals or in the manual, how the supply can be used. Here are some examples. |
| JohnPen:
As others have said Isolated outputs with maximum current equal to the lowest current rating power unit is fine for PSUs in series. For parallel no need for Isolated but tricky voltage matching adjustment to share the load with relatively equal amounts of current. However for something like charging a car battery, which pulls the output voltage down, and assuming each power supply has an adjustable constant current output you can just wind the volts to greater than say 16v and set the constant current of each supply to supply the current they can handle quite safely. I didn't have a battery charger at the time and my home built linear power supply gave out 2 x 2A . :) I wouldn't recommended for everyone to try this because some PSU designs might be very unhappy with this type of operation. However for my PSU this method was used a number times over the years with no problems. The supply in question is now over 38 years old, used a lot for hobby, and has only needed replacement electrolytics so far. :) |
| james_s:
Hot swap server PSUs are designed to operate in parallel and share the load. With modification to float the DC ground they can be operated in series, they're not really designed for that but lots of people including myself do it. Cheaper supplies like wall warts and such are not designed to run in series or parallel however I've done that with success. I consider that to be one of those things you shouldn't really do but if you don't care about possibly damaging a power supply there's a reasonable chance it will work. |
| Zero999:
Load sharing is unimportant. In order to be safely connected in parallel, only three things are required from the two power supplies: * The power supply will go into constant current mode when overloaded * A slightly higher voltage, than its set-point can be connected to its output, without damage or instability. * It's stable when unloaded. The power supply with the higher voltage setting will provide all of the current, up until the current limit is exceeded, its output voltage will fall to the same level as the other power supply which will supply the extra current. |
| Brumby:
--- Quote from: Zero999 on January 13, 2019, 07:15:50 pm ---Load sharing is unimportant. In order to be safely connected in parallel, only three things are required from the two power supplies: * The power supply will go into constant current mode when overloaded * A slightly higher voltage, than its set-point can be connected to its output, without damage or instability. * It's stable when unloaded. The power supply with the higher voltage setting will provide all of the current, up until the current limit is exceeded, its output voltage will fall to the same level as the other power supply which will supply the extra current. --- End quote --- The Op was talking about ATX power supplies, not lab style. Current limiting in the form of which you are speaking would certainly address the load sharing issue - but this is not a feature of ATX supplies, in my experience. |
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