So while trying to see if I could shock myself today using two of these in series
http://www.rcgroups.com/forums/showt...4#post14004361
here is what I found out.

While being powered with 120V AC as per my wiring drawing there is less than 1 volts DC between the case. Even if both case are touching each other and even if the green earth ground is connected to both of them there is no shorting.

Now that what I experienced with these two may not be typical of all of them but then again perhaps these power supplies are indeed very different than the IBM 235 and most personal computer power supplies.

This brings up something interesting posted earlier.

http://www.rcgroups.com/forums/showp...9&postcount=90

Snip:

Quote:
All switching PSUs(AC adaptors) are isolated inside using transformers with strictly insulated primary and secondary windings instead of a single coil. They CAN appear as a non-isolated one if the manufacturer wants it to be.
Charles

Hi , should the AC ground be floated ?

That's very interesting as I would love to wire mine for 24vdc but the thought of floating grounds scares me.

What is safe,what is unsafe, how to properly uncouple the ground how to redneck it ,was discused in great detail years ago.



http://www.rcgroups.com/forums/showp...2&postcount=75

Perhaps start here and read 20 or so post

http://www.rcgroups.com/forums/showp...&postcount=113

Charles

I saw this post and i have the same ps's but just want to check if this is right ?

Originally Posted by everydayflyer

I just love it when you find out that all tha worrying was for nothing.

OK perhaps the jury is still out. My findings should not be considered conclusive .


Update This is a significnate ,please read carefuly.
If you are using these very same power supplies as singles then nothing has charged however if you are using them in series ...

I have done more testing and determined that in fact the DC grounds are in fact isolated from the AC (case/earth)ground. What does this mean. In simple terms it means that the can be used in series with the earth ground connected to both units and it also means that the cases do not have to be isolated from each other(tey can touch) and it also means that with the earth ground connected they are now much safer to use.

Very same being hp Series ESP 114
Part # 192147-001

which have 12V and 55A output among others.

This is only my experience with two of these power supplies.

Charles

As posted above

Perhaps start here and read 20 or so post

http://www.rcgroups.com/forums/showp...&postcount=113

Charles

My findings have not changed and I know of several others with same findings however some did in fact find that the cases were hot if the grounds were not lifted.

There is really no point in covering the same things which were covered back then.


Charles

Hello Guys....

After a lot of reading from your posts,and without your posts i could never do it, i decided to make mine own , since i fly a 700 sized heli, i always need a lot of batteries...

I normally take to the field 8 * 6S 5300mah packs...

Mine first afraid was having one case not connected to earth...So after a lot of reading, and with the posts from Mr Mel and pics, since both mine power supllies were connected between the DC- and earth, i took the R381(i believe it's correct, correct me if im wrong) 0 ohm resistor from the 2nd PS the 24V one, leaving the DC- floating, but being able to connect both PS to earth...

Here follows some pics to show:
Both are completely insulated by 12mm plywood in the middle, and 6mm plywood for both sides, top and bottom.
After that i made a 1.5mm stainless steel casing that goes over the plywood..
Seems fine to me and keep it compact..

Hope you like it...












After connecting them in series, without plywood measured both DC and AC voltage from earth to case and ground and everything is ok!

Best Regards to all of you....

Looks great. Which charger do you use?

Nice job GRacing, it looks good. Very clean and sanitary looking.

Originally Posted by earlwb

Nice job GRacing, it looks good. Very clean and sanitary looking.

Originally Posted by feathermerchant

Looks great. Which charger do you use?

Hello Guys


Thank you for your valuable input...
..Sanitary looking..I work with stainless steel in the past 10 years from furniture to sanitary.. lolo

Mine charger is, at the moment the Hyperion EOS610i duo, wich doesn´t put more then 16 amps at 24 volts on the power supplies..but has soon has mine friends will need power source, i will get better data...By know i´m limited by the 180 watts from each port of the charger, wich has 2,meaning that at max voltage on the 6S, 25.2 volt i get 7.15amp aproximatelly....*2 i get 15 16 amp, 20 at most!


Feel happy that both of you liked them..

Sorry for resurrecting an old thread, but these power supplies are still an extremely viable option for our charging needs. They can be purchased for about $25 shipped from EBay, ServerSupply.com, and other sources. I thought I would share my recent modification with you. I wanted to make something really slick and cool at the same time being completely functional and fairly inexpensive. Feel free to contact me with any questions.

Parts:

• Ammeters on Ebay
• Voltmeters on Ebay
• RadioShack Lighted Switch
• RadioShack Project Enclosure 7x5x3 (I cut mine down from 3" to 1.75" tall)
• Lighted Fan (I had several laying around my computer parts shelves) This is a good one if you don’t have one.
• Monokote Trim Sheet Midnight Black (TOPQ4109)
• 1/2” Copper tubing. (I had all these pieces in my garage).
• 10AWG Stranded Wire ($0.53 per foot at Lowe’s)
• ESP114 or ESP114A HP/Compaq Power Supply
• Rubber Grommets (Lowe's)
• Assorted small rc wire and connectors (JST/bullet/PowerPoll/etc. Whatever you have lying around).

Please see the pictures and their captions for the details…
.

Originally Posted by T3chDad

Sorry for resurrecting an old thread,

I'm glad you posted this, very interesting info.
Thanks

Nice !

Im having issues with one of my units. It wont start up with a green light. The orange light comes. Not sure what the status light indicates. My 2nd one runs like a baby..

I had that issue when I had reversed polarity on the fan plug. The unit will show amber light and will not start if the fan is unplugged or, in my case, reversed polarity. I wasted a couple of hours troubleshooting mine before I figured it out. If you haven't messed with the fan at all, this is probably not a likely cause but it may be worth trying another just to see.

Hope this helps!

It works now.. Looks like there was something wrong with my jumper plug at the back of the unit, or i had placed it at the wrong pins... But, the fact that you told me to check the fan, as I did a fan replacement, I did get to check the rest of the unit and found the error.. =D

Great job I just joined to find out how to make this power supply work for my roto caster machine and just in time.
I got it working great.
Thanks for your hard work and info. Also I bought mine on eBay for 20 bucks shipped.
I'll put this info on my site to help others too.
(Theplasmacutterman.com) or just type in ( homemade tools and more). Thanks earlwb