How to build a $20 47A power supply

[kazuaki]

Originally Posted by lincpimp

I did something similar a while back. Not as nice, but it worked.

I like that, nice and heavy duty!!

[BrianG]

Another little update for this little PS unit.

I got another one of these and was doing my voltage boost mod when I accidentally discovered the ground connection for the sense/feedback circuit is not even needed. After doing some more playing around, a 1.5k ohm resistor between the main 12v terminal and pin 5 is all that is needed to boost the output to 13.2v.

BTW, the max voltage you can get out of this is around 13.5v. At 13.6v, the PS shuts down.

Also, for those that think the fan is a bit loud on 12v: If you run this PS at 25A or more for extended periods (>1/2 hour), the air coming out the back is pretty toasty. I figure even if this unit is 90% efficient, 35A @ 13.2v is 528w which will produce 53w of heat. That's quite a bit, so if you do turn down the fan, I wouldn't go too far.

[Metallover]

Brian you're the man! Thanks for posting!!

[mamba max1]

Here's mine, but with a 42A PS. When I charge 2 lipos (3s 5800) at 2C (11.6A each for a total of 23.2A from the PS) it barely even gets warm.
















Yes, the lid is burnt. After I went through the extreme hassle of making a false bottom that fit (major PITA) the charger did not fit. I was not about to toss all my work in the trash so I softened the lid up with a lighter and expanded the it a bit. Made it fit. I use the velcro from hobbycity to hold everything in place. Plus a side to barely fitting is it doesn't rattle around inside at all, even when upside down. The velcro is crazy, its a bear to pull the charger and PS out of the box.

I have the charger plugging into the false bottom so that I can unplug it from there and into some alligator clamps for charging from a car. :) BTW, the box is amazing. Makes charging easy, and portable while keeping it protected.

ok for a semi-noob. With the original ps, which main line do you use for the charger(outsides or insides)? Can you use it to power 2 chargers off of different sets of lines?

Ok BrianG I took off the hot swap connector like this http://sites.google.com/site/tjinguy...projects/HP47A
wondering whow would I put the 1.5k ohm in to boost volts and what watt of resistor did you use? I have 12.45 now.

[BrianG]

Originally Posted by fordman86

Ok BrianG I took off the hot swap connector like this http://sites.google.com/site/tjinguy...projects/HP47A
wondering whow would I put the 1.5k ohm in to boost volts and what watt of resistor did you use? I have 12.45 now.

Honestly, if you are getting 12.45v now, there really is no reason to mess with it. ~13.2v is not a whole lot more voltage for the work required. But if you still want to:

The pic below is the first PS I modded before I realized I didn't need as many wires, but all you need to do is attach the 1.5k ohm resistor to the red and white wires (the ground isn't needed). Resistor wattage can be your typical 1/4w.



In this pic, you can also see the jumper wires I added to turn the supply on without having to mess with the little pins.

Be aware that I cut the standalone purple and blue wires (-12v and 5v aren't used) and cut away the PCB where they attached to give me room for those white and red wires in the pic above.

Ok will leave be but I modded even further and took that whole board out per the link I posted before. It's at the bottom of the page.

Just finished mine and wanted to share it. What an awesome power supply that has tons of power. This thread is what got me started and I thank everyone here for your knowledge and support.

Terry
http://www.youtube.com/watch?v=KB_MghvoqHE

[BrianG]

I just posted why you are getting 17v on your YT vid, but for some odd reason, it appears to be posted from peterscalab??

Originally Posted by BrianG

I just posted why you are getting 17v on your YT vid, but for some odd reason, it appears to be posted from peterscalab??

I saw that. That's weird. Thanks for clarifying that up for me. I understand now.

Here's mine all done

[snellemin]

That blue right thur is gansta. Looking good man.

[silentbob343]

Originally Posted by Divey1130

Just finished mine and wanted to share it. What an awesome power supply that has tons of power. This thread is what got me started and I thank everyone here for your knowledge and support.

Terry
http://www.youtube.com/watch?v=KB_MghvoqHE

Hot swap and IIRC the 208B requires 18v to support 350w.

I see Brian already answered the 17v question.

[mistercrash]

I haven't read all the posts in the thread so sorry if this has been discussed. I have read in here that if you go with two server PS to have a 24V power supply, the two can't be touching because you have to remove the AC ground on one of the units. I hope I understood correctly. This guy here says that he removed the DC ground on one of the units instead retaining the AC ground on both units so the boxes can touch with no problems.





Maybe someone with more knowledge than me can confirm that this way of doing it is safe.