Corsair 400CX 45A off of the +5V rail

[HangFire]

I just received a new 400CX, and before cutting out the MIR bits decided to test it.

OCP cut off at just over 30A on the +12V rail, just like it should.

I got 45A off of the +5V rail for 15 seconds until my car battery load tester started to complain and I stopped the test. (+5V is rated for 20A). I used four 14Ga wires in two different Molex connectors on different cables into the two clamps so as not to overheat one cable.

To its credit, it didn't burn out. I repeated the test a second time and filmed it for YouTube:

http://www.youtube.com/user/hangfirew8?feature=mhw4#p/a/u/0/nB0vkBgFdFI

Question: what is supposed to happen here? Isn't there supposed to be an OCP that kicks in on the +5V rail too? Is that too much to expect from a $45 power supply?

-HF

[Zero82z]

There should technically be OCP on all rails, but I would imagine most PSU manufacturers don't bother with it on the minor rails since the chance of an overload is incredibly small.

[Makalu]

always wondered how those would work...they're cheap at harbor freight...anyway the OCP limit per the guides there is "before reaching or exceeding 240VA" which is 48A on the 5V. Technic3d's shut down at 47A

http://www.technic3d.com/article-777,6-corsair-cmpsu-400cx-400w-netzteile-fuer-den-office-pc-teil-3.htm

so you probably just need more load. The label rating of 20A takes several things into account besides just the safety regulations.

[Hondacity]

i want that load tester! lol

[Travis]

HY-510N chip didn't provide OCP on those rails. I guess the 30A protection on +12V rail is actually OVP/UVP/OPP.

[HangFire]

always wondered how those would work...they're cheap at harbor freight...

Yeah I got a credit on a recall, combined it with a coupon and got it for under $US 50 delivered. :D

anyway the OCP limit per the guides there is "before reaching or exceeding 240VA" which is 48A on the 5V. Technic3d's shut down at 47A

http://www.technic3d.com/article-777,6-corsair-cmpsu-400cx-400w-netzteile-fuer-den-office-pc-teil-3.htm

so you probably just need more load.

The Load Tester is supposed to be 1 Ohm when cranked down (as it was). To get to less than that, I'd just have to use a bunch of Copper! I'm not so keen on that idea, as copper can weld (braze) itself to stuff... might be hard to end the experiment should things get hot.

The label rating of 20A takes several things into account besides just the safety regulations.

It didn't quite get to 47A, though the load tester is not calibrated per se, and if it was it was calibrated for 12V not 5V. Still, it read a hair over 45A, not quite 46A by eyeballing it... so from what you are saying, it is staying safe, in a sense, even though it did not shut down.

So what is the verdict, would you all trust a new low-middle end M/B+CPU+RAM to this device?

-HF

[HangFire]

i want that load tester! lol

I understand they are just the ticket for testing Honda batteries. :)

[Hondacity]

lol i didn't know honda made batteries

i saw that load tester but its red...yours is blue...i wonder what the difference is...

[Makalu]

Yeah I got a credit on a recall, combined it with a coupon and got it for under $US 50 delivered. :D



The Load Tester is supposed to be 1 Ohm when cranked down (as it was). To get to less than that, I'd just have to use a bunch of Copper! I'm not so keen on that idea, as copper can weld (braze) itself to stuff... might be hard to end the experiment should things get hot.



It didn't quite get to 47A, though the load tester is not calibrated per se, and if it was it was calibrated for 12V not 5V. Still, it read a hair over 45A, not quite 46A by eyeballing it... so from what you are saying, it is staying safe, in a sense, even though it did not shut down.

So what is the verdict, would you all trust a new low-middle end M/B+CPU+RAM to this device?

-HF

hmm well you confused me...needed more load not less. 1 ohm would be 5A on the 5V (25W)...you can get some resistors for just a few dollars if you want a lower load than that.

Anyway I think the idea with the over current protections is to prevent fires in case of a short circuit...which could be on one of the PSU's 5V wires but it's not like you get military industrial strength wiring in more expensive PSU's...a short somewhere else isn't the PSU's fault and they just want it to not start a fire so yeah no qualms about using it

[HangFire]

I was thinking 0.1 but wrote 1... but, Er, yeah, to work at its full rating, to pull down 500 amps at 13.8V would mean about 0.0276 ohms.

I'll go ahead and use the P/S.

Thanks!
-HF

[HangFire]

lol i didn't know honda made batteries

i saw that load tester but its red...yours is blue...i wonder what the difference is...

I got mine on-line about a year ago... maybe the store models are red, or maybe there was a change in color at some point.

-HF

[Makalu]

I was thinking 0.1 but wrote 1... but, Er, yeah, to work at its full rating, to pull down 500 amps at 13.8V would mean about 0.0276 ohms.

I'll go ahead and use the P/S.

Thanks!
-HF

ah ok lol yeah that makes a lot more sense now ;) .1ohm would be 50A with the 5V so it sounds like it's a bit off...but if you wanted to load it a bit more it'd be no big deal but you should be connecting up to more than two 5V's wires or risk burning something there maybe with 25A thru one 18AWG wire.

Here's a photo of the insides in case you're curious:

http://www.neon-john.com/EV/Battery_tester/03.jpg

carbon pile is the round thang of course and there must be some static resistance thru the two big straps on the side....the plate sticking out on the right side is the current shunt...timer and alarm on the PCB. Kinda surprised they get so hot so fast with just a <250W load...

[370forlife]

45A off the 5v is a testament to ST Microelectronics, the 5v on these are regulated by a 30A, 30v ST schottky.