dc power supplies

Old 06-12-15, 12:43 PM
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dc power supplies

I was told I could use a switching power supply that is equivalent to the battery pack that has a short run time. In my case I was told I need an 18 volt with 20 amps available in the 300 - 500 watt range. I cannot find anything I can afford in this configuration.

This brings up the question. If I use a power supply that is a quad, each supply rated at either 18 or 24, with 5 amps each connected in PARALLEL, will the available amperage go from 5 to 20,5x4, stay the same as the voltage does, or go down by a factor of 5? In series same question. If I use multiple single power supplies at 18volt/5amp same rules apply? I have many printer power supplies in the 18 volt, 3 amp range. I could use those in parallel if the available amps of each is multiplied by the number of supplies. Advice please.
Old 06-12-15, 01:56 PM
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Power supplies don't always like to be connected in parallel or series; they have to be designed for that application. So you can't assume you can take any old supply and series or parallel them. You can blow stuff up pretty easily if not designed right.

Having said that, if you connect them in parallel, the voltage will stay the same and the current ratings will add.

If you connect them in series, the voltages will add and the current rating will be equal to the lowest current rated supply (say you had three 5amp and 1 4amp in series, the current rating would be 4 amps).

If I were going to try paralleling several random power supplies, I'd put a low value resistor (maybe 0.1 ohm) in series with each supply along with a fuse appropriate for the rated current of the supply.

Good luck! Oh, you may want to check some of the surplus electronics places online...you might find what you need at an affordable price.
Old 06-12-15, 09:36 PM
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