Post Reply 
 
Thread Rating:
  • 0 Votes - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Using PC power supplies.
Author Message
benny Offline
Member
***

Posts: 332
Joined: Sep 2008
Reputation: 5
Post: #1
Using PC power supplies.
There have been several threads on use of PC power supplies for bench testing of hydroxy (HHO) generator.

I pointed out in an earlier post that some, if not all, PC PSUs should be de-rated for use with these generators. Further to this please note that older PCS used more power from the 5V PSU outputs than from the 12V outputs. Newer PCs use more power from the 12V outputs than from the 5V outputs. Power ratings of these PSUs are for total power output for these.
PC PSUs have been designed according to requirements of the PCs at design time.

Older PSUs may not be suitable for use with hydroxy generators for the reason that there might not be sufficient power available from the 12V lines for continuous use. They will most likely suffer catastrophic failure.

Before using any PC power supply for this, I recommend that any potential user read the following Wiki.

http://en.wikipedia.org/wiki/ATX

This Wiki gives more information on the differences between older and newer power supplies.
(This post was last modified: 01-23-2009 06:12 AM by benny.)
01-23-2009 06:11 AM
Find all posts by this user Quote this message in a reply
gtkco Offline
Member
***

Posts: 322
Joined: Jun 2008
Reputation: 0
Post: #2
RE: Using PC power supplies.
So far I have been using the rule of thumb of multiplying the rated amps of each voltage by 70% to get its "continuous" amp level. This seems to be working ok for the 2 PS I am using. One is an old IBM AT unit (about 180watts) and a new ATX PS at 650 watts. The 650 gives me at least up to 20 amps "continuous" on all voltages (3.3, 5v and 12v).
01-23-2009 01:56 PM
Find all posts by this user Quote this message in a reply
benny Offline
Member
***

Posts: 332
Joined: Sep 2008
Reputation: 5
Post: #3
RE: Using PC power supplies.
(01-23-2009 01:56 PM)gtkco Wrote:  So far I have been using the rule of thumb of multiplying the rated amps of each voltage by 70% to get its "continuous" amp level. This seems to be working ok for the 2 PS I am using. One is an old IBM AT unit (about 180watts) and a new ATX PS at 650 watts. The 650 gives me at least up to 20 amps "continuous" on all voltages (3.3, 5v and 12v).

OK on your rule of thumb for de-rating. If it works for you, then must be ok.
Most newer designs of PC PSU are protected against short-circuit and over-voltage problems, so should not be much of a problem with those newer models.

Warning was aimed at older type power supplies which may not incorporate these design features.

Short circuit protection in newer designs should close down the PSU on over current detection and effectively act as a maximum current regulator.

I would still advise to go for max power rated PSU available, and de-rate even these newer designs tho'.
New ones are so inexpensive it is hardly worth using older used PSUs.
Better safe than sorry.
01-24-2009 04:25 AM
Find all posts by this user Quote this message in a reply
gtkco Offline
Member
***

Posts: 322
Joined: Jun 2008
Reputation: 0
Post: #4
RE: Using PC power supplies.
(01-24-2009 04:25 AM)benny Wrote:  Short circuit protection in newer designs should close down the PSU on over current detection and effectively act as a maximum current regulator.
I think my new unit does just as you say, but I decided to push it closer to its rated amps just to see. (of course isn't this how we get into trouble. Oh yah!) As I pushed the unit up I notice that hot sort of electrical over heating smell. This happened before it reached its max rating or cut off so rather than risk it I went back to the 70%. At this level, it seems to be very happy and I have run it for hours at these amps (about 20). So as you suggest below, de-rating is a very sound policy even for the new ones.

(01-24-2009 04:25 AM)benny Wrote:  I would still advise to go for max power rated PSU available, and de-rate even these newer designs tho'.
New ones are so inexpensive it is hardly worth using older used PSUs.
Better safe than sorry.

I also agree that its worth the $20 bucks for the new ones. The older ones aren't going to have enough watts and amp output to adequately do the type of testing one wants to with HHO. You'll end up building the old one only to find out it isn't up to the job and have to buy a new one anyhow (like I did).
All good advice. Thanks Benny
(This post was last modified: 01-24-2009 08:32 AM by gtkco.)
01-24-2009 08:31 AM
Find all posts by this user Quote this message in a reply
Post Reply 


Forum Jump:


User(s) browsing this thread: 1 Guest(s)