Connecting Two Power Supplies

[Sanghera]

Hi all,
I was just wondering if it is possible to wire two power supplies together in such a way to increase the voltage. Kind of like wiring two batteries, or does it not work this way for power supplies? I have two 12 volt power supplies, one is 4 amps and the other is 10 amps, I want to join them so that they make a 24 Volt supply, would I also add the amperage? And how would you wire this?
Thank you very much for the help.
I really appreciate it.

[H500]

If you hook them in series you will get 24v, but you need to limit the current to the smaller of the two (4 amps). Otherwise, you could burn out the transformer.

[Sanghera]

Why would I have to limit the smaller of the two, what would the output amperage be in the end when mixing a 10 amp and 4 amp?
Thanks.

[Sanghera]

Also, what would I have to limit the smaller of the two to? Would I limit the bigger to the exact same? Also, would I need any diodes to make sure no crossover happens if that is even possible?
Thanks.

[murphy625]

Your voltage doubles but amperage can only be as much as the weekest link. (in this case, its your 4 amp supply)

An example: If you hooked up your two supplies and for some dumb reason, you had only a tiny wire to connect the output with, your amperage would be limited to the amount of current (amps) that tiny wire could carry. (assuming the tiny wire is only big enough to carry something less than 4amps). If you draw more amps than that tiny wire can handle, it will heat up and melt into two pieces like a fuse does.
The components of your power supply are more or less just like that tiny wire example.

Hope this helps.
Murphy

[JFettig]

Thats something to be VERY careful of, if its a switching power supply, a lot of times it wont work, you must be aware of the max voltage of the capacitors in these power supplys, the capacitors will blow up, and when I say blow up I mean big bang, stuff flying, possible injury. You may want to consider getting a couple of transformers and running those in series and getting a proper size capacitor and bridge rectifier. The capacitor shoudl be almost 2x the voltage max than your voltage ratings on the transformers because they will put out 1.414 times the rated voltage I think it was.
My '48v' power supply on my mill that I bulit is putting out ~70v

Jon

[Al_The_Man]

Another thing to watch out for with separate supplies is if the commons are at ground potential. If they both are then you cannot do it. Only if one is or neither, If neither then you can set one of them as common ground.
Al

[joecnc2006]

ok has anyone done it? if so got any pics?

Joe

[Kenwood714]

Yes I have done it but with all above considerations. The fact is if you are working with supplies that have isolated grounds you can do it. If you just looking for 24 volts at 4 amps and your 2 supplies have isolated grounds then no problem. If you want the 14 amp current rating it won’t happen. You have to look at it as a loop. Current flows from the supplies to your motors and back. You have a 4 amp supply. It will not handle the extra 6 amps of current supplied by your 10 amp supply. Therefore the transformer , diodes and other components in the smaller supply will fail. If you had 2 identical 10 amp, 12 volt supplies and you wired them in series, you would have a 24 volt 10 amp supply. It sounds like your best bet is to look for a new supply depending on your needs. I hope this helps, Ken

[Sanghera]

Thanks everyone for the help.
I really appreciate it.

[Gern]

I have (2) 24 volt 8.5 amp supplies. Can I hook them up in parellel to get 24v and 17 amps? Here is the link to the power supply.
http://www.mpja.com/productview.asp?product=15080+PS
Gern

[Kenwood714]

Gern,
Parallel supplies is a different story than a series situation. The ones you are looking at I would not suggest hooking in parallel. In a parallel situation you have to have supplies that are designed for this purpose. One as a master and one as a slave. They will have identical output voltage and will track together sharing the current. Even though these supplies you have are made by the same manufacture they will have slightly different output voltages and they will not work as a team but tend to fight each other. Eventually one will fail. You can use diodes to isolate the supplies but this will effect the output voltage. Best bet is to find a single supply rated for what you need.
Ken