Networking Six 5V 70A Supplies

[DTB Radio]

I found 6 5-volt 70-amp supplies on Ebay for around $125.00 total. I plan on networking them to make myself a single 15-volt, 140-amp supply, and see how well the idea works. I will keep you all posted as I get time to put it all together.

 

[DTB Radio]

Got the basic supply all put together. I haven't tested it to really high output levels yet, but it handles 25-30 amps with almsot no voltage drift whatsoever. I'll continue to post updates, and possible photos.

 

[C2]

So you are running a bank of 3 in parallel?

I had an idea to run just two supplies in parallel. It would not work since they were very well regulated with shutdown.

What would happen is that one supply would supply all the current it could, up to it's limit of 50A, then the voltage would drop when it shut down and the other would kick in to supply the current, but if the draw was more than 50A, they would both just shut down.

That was because no matter how close I'd set the voltage, one was just a hair higher or lower than the other. So the higher voltage one would get the workout.

Even when I connected remote sensing to various points, like the common node, or crossed the sensing to the opposite supplies output, it would not work, at least not consistently well enough to have clean regulated output to the max of 100A.

Now, connecting them in series was no problem...

If they were not regulated, then it would be OK...

 

[Captain Kilowatt]

If they were not regulated, then it would be OK...

Really? :? That is where I had problems,unregulated supplies in parallel would not work but regulated ones worked fine.I was working on a 200 watt police siren and tried to power it from a pair of 20 amp unregulated supplies and they kept shutting down and the load was going nuts between them.I eventually borrowed a pair of regulated supplies and all was well.BTW a 200 watt siren inside a building is really LOUD! :shock:

 

[DTB Radio]

I have 2 banks, each bank consisting of 3 15-volt 70-amp supplies in series. The 2 banks are wired so that they can be tied parallel to each other, but are actually installed in my case as 2 seperate 70-amp 15-volt supplies. I even gave them each their own 110-volt mains cord and power switch. I noticed that when they are tied together and I try to start either one by itself, it tends to stall. If I start them at the same time, they fire up ok, and they seem to deliver the current with no trouble. I still haven't tested them beyond about 25 amps yet.

On a side note, I made a dumb mistake and cut out the front panel for a nice large volt-meter movement, but failed to measure the depth of the meter. It wouldn't fit, its contacts being right against the case of one of the supply banks. Now I have this 2.5" x 2.5" hole to remember it by, lol! I'm going to just go digital with the metering, and make a nice instrument plate to cover the gaping hole.

 

[DTB Radio]

Well, I finally got to test each supply bank with a Texas Star 667 amp, and each bank handled it, along with the radio and a couple other low-draw accessories, with no dimming of anything. I have digital metering coming in for it, and I will try to get pictures up soon.

I still need to mount and connect a couple fans to help keep it cool, but so far, it hasn't gotten all that hot.

 

[KD0FBK]

That is cool, I was going to try the same idea once I gathered enough power supplys.

Are you cutting the traces to remove the power negative from the chassis ground?

 

[DTB Radio]

Nothing is cut. The ground of each of the supply banks goes right to the aluminum chassis, and the mains ground is certainly left intact. Sorry I haven't posted pics yet, but the project is still not totally done. I got digital metering in for it, but not installed yet. I still need to add cooling, too.

 

[DTB Radio]

I finally got around to installing a current shunt, and digital volt and current meters, along with a cooling fan. Its not the prettiest item ever built, but I've pulled over 60 amps from it so far without it breaking a sweat.

I still want to post pictures, I just don't seem to find enough time....

 

[C2]

I don't see it breaking a sweat until you get up over 70 amps. After all, just one bank should be able to supply that.

It would really be interesting to see what happens when you start getting over 100 amps.

Just make sure you have that fire extinguisher handy.

 

[DTB Radio]

Ok, I hooked up a Texas Star 1200 and a small driver amp (150 watts or so), and the supply seems to be handling the load with no problems. My Wavenode system recorded peaks of 1550 watts, and the supply voltage hovers right at 15. I over-drove the 1200 to see how many amps I could draw, and I was able to pull 125 steady amps from it for a couple seconds. I didn't want to damage either of my amps, so I just did that for about 2 seconds.

Project Successful!!

 

[C2]

I keep waiting for the smoke and mirrors post.

 

[DTB Radio]

Pulled a bit over 140 amps from it today. I had someone watch the current meter while I keyed at progressively higher drive levels for about 2 seconds each, with a short break in between. Never dropped below 15 volts. I don't think the smoke and mirrors post is in the foreseeable future!

 

[C2]

probably not again anyway

 

[Toll_Free]

So you are running a bank of 3 in parallel?



That was because no matter how close I'd set the voltage, one was just a hair higher or lower than the other. So the higher voltage one would get the workout.

Actually, putting a small amount of resistance from each supply B+ to the load would have negated that effect.

It's called a current splitter... It would have made each supply ramp up independantly.

Same thing smart builders do if they are using multiple transformers in the HV stage... Put a small amount of resistance between each transformer on one end, and you magically have no more problems sharing the loads.


--Toll_Free