Capacitor Lifetime

**c_hegge** · 11-25-2011, 12:26 AM

Re: Capacitor Lifetime

Typically, a cap is rated at 2000hrs at 105*C and at the maximum rated ripple and voltage. every 10*C below 105*C doubles that lifetime. The fact that the cap won't be run at their maximum rated voltage and ripple will further increase the lifespan.

**shovenose** · 11-25-2011, 12:27 AM

Re: Capacitor Lifetime

Originally posted by c_hegge

Typically, a cap is rated at 2000hrs at 105*C and at the maximum rated ripple and voltage. every 10*C below 105*C doubles that lifetime. The fact that the cap won't be run at their maximum rated voltage and ripple will further increase the lifespan.

I see... with those factors combined can I expect 20000 hours out of a capacitor?

**c_hegge** · 11-25-2011, 12:36 AM

Re: Capacitor Lifetime

Probably, if not more. there's a reason why I still see pentium 2s and 3s with perfectly good caps (when they are good brands, that is).

**shovenose** · 11-25-2011, 12:39 AM

Re: Capacitor Lifetime

Alright, makes sense - now, should I be more worried about the motherboard or PSU caps?

**retiredcaps** · 11-25-2011, 01:05 AM

Re: Capacitor Lifetime

Originally posted by shovenose

Also, what can I do to make my servers happier?

If you have servers that have peripherals like floppy drives, cd-roms, modem cards, etc and don't need them, disconnect their power molex so they don't add to the heat generation.

It may not be much, but every little bit helps?

**mariushm** · 11-25-2011, 04:16 AM

Re: Capacitor Lifetime

Read section "Useful life"...well, you can read all as it's useful info but this section on pages 8-10 explains your question :

The number of hours doesn't say the capacitor has a "warranty" of 2000 hours and then it may die.

For non-solid aluminum capacitors the influence of temperature on useful life is approximated by the so-called ‘10 K-rule’. The ‘10 K-rule’ states that double the life time can be expected per 10 K temperature decrease; this principle is derived from the well known law of Arrhenius about acceleration of reaction processes.

The exact temperature dependence of useful life for a particular range is given in the corresponding detail specification in the ‘life-time nomogram’ (‘Multiplier of useful life’ graph in the detail specifications). Detailed performance requirements, on which the definition ‘useful life’ is based, are also stated in the relevant detail specifications.
Exceeding those requirements shall not necessarily induce a malfunction of the equipment involved. The performance requirements offer advice on the choice of components and
design of the circuitry.

Based on the Arrhenius law and on experience for some decades, a nomogram is specified in the detail specification for each range, where the influence of ambient temperature and ripple current on the expected useful life is shown. Ripple currents at other frequencies than specified must be corrected using the frequency conversion tables in the relevant detail specification.

So how much a capacitor will stay within specs depends on how much ripple introduces heat and how much the temperature around it stays low.

Page 10 has some examples on how to estimate how much the capacitors will last. Do note that those charts with the multipliers are "typical" ones and some capacitor series may be better or worse than those but the paper gives you a good idea on how to determine.

Also, what can I do to make my servers happier?
If you have servers that have peripherals like floppy drives, cd-roms, modem cards, etc and don't need them, disconnect their power molex so they don't add to the heat generation.

Floppies and cdroms and all that are basically dead when not in use, they don't generate heat. Don't bother removing power from parts and all that.

The server will be more likely to fail when you reboot it once after keeping it on for a long time - the inrush current in some component may trip a fuse or burn something or the mechanical parts of the hard drive may fail even though it kept spinning for months/years.

Best thing you can do for hardware is to keep the temperature stable and average, not high or very low. High temperature hurts but so does very low temperature - don't go overboard. Just open it up and blow the dust once in a while and you'll do fine. The power supply is more sensitive to heat and that along with the cpu cooler fan would probably die first, if the hard drive lasted already a few months of use (majority of hdd failures are within 1-4 months of use).

later edit: my advice would be to cut down on the folding at home ... those processors are slow enough that your contributions are ridiculously small - what your system does in a day is probably done by two quad cores/i7 in a couple of hours. Overall your contribution is insignificant but you're damaging the hardware with heat and spending money on power.
In fact you can probably spend 40-50$ on ebay on a cheap nvidia gtx 260/ 4850/5450 and use it for folding on gpu and get better scores than those old systems together.

**c_hegge** · 11-25-2011, 04:26 AM

Re: Capacitor Lifetime

Of course, though, these rules assume good caps. With a bad cap like KZG, you won't get long at all. If they were brand new when you got them, you'd be lucky to get 1 year out of them in a hot environment

EDIT: If you have any GSC/Sacons in there, you'd be lucky to get two months.

**shovenose** · 11-25-2011, 08:11 PM

Re: Capacitor Lifetime

Alright, I measured, my closet is about 82 degrees

**PCBONEZ** · 11-26-2011, 12:37 AM

Re: Capacitor Lifetime

Originally posted by shovenose

I see... with those factors combined can I expect 20000 hours out of a capacitor?

No.
The 'Lifetime' in data sheets has nothing to do with 'useful' lifetime.
It is called 'Load Life' or 'Endurance Lifetime' among other things.

No cap manufacture makes a claim about [or spec for] 'useful' lifetime.

The lifetime in data sheets is basically how long you can apply max voltage, max ripple, and max temp at the same time and the cap will still be in spec when returned to nominal conditions.
- Nothing says for how long it will stay in spec afterwords.

If your actual conditions are max voltage, max ripple, and max temp at the same time then you have other problems.
It's not a real world condition.

Here is the tricky part.
Because Useful Life and Load Life are dependent on the same factors they are proportional.
- So if you change temp and double one, the other will be doubled also.
.

.
Nichicon VR [85C @/2000Hr] start going bad after about 4-5 years 24/7 in poorly cooled cases.
A 105C @/2000Hr cap should last 4x as long in the same conditions, so, 16-20 years 24/7 in a hot case.
.
IOW: Use 105C caps, descent cooling, and don't worry about it.
.

**shovenose** · 11-26-2011, 12:47 AM

Re: Capacitor Lifetime

Alright. So say I'm running a Rubycon MCZ capacitor on a motherboard VRM, right next to a hot CPU, so the capacitor might be at...hmm... 90C. There's a decent quality PSU that's outputting clean voltage to the VRM. All in a tiny HP case. How many hours can I expect out of that capacitor in that configuration?

**PCBONEZ** · 11-26-2011, 01:24 AM

Re: Capacitor Lifetime

Given the room itself is over 80F probably close to what you'd get with a Dell Clam-shell Optiplex.

Can't tell you anything for sure.
No one can.

The only thing you can actually ~DO~ is try to keep the closet cooler and/or rebuild into a better cooled case.
.

**ThePCDoctor** · 11-26-2011, 10:55 AM

Re: Capacitor Lifetime

A point of info about the PSU's formerly mentioned......

Not long ago, I emptied my junk box of 14 bad PSU's.
All but two of them were Bestec 300 W. The other two were cut-rate brands I found at computer shows. Neither one lasted more than a year in service.
(All of them, had those bad Chinese cap's.)

The problems? All had multiple bulging and leaking capacitors.

I recently took a Bestec 300W out of a working desktop PC and opened it up to check the caps. One was seriously bulging, but the supply still worked. So I ordered a replacement cap from "Badcaps.net" and I've since replaced it and put that supply back into service, in one of my test PC's.... the one I'm currently testing windows 8 DP on. With a Bestec PSU, that PC will never leave my shop, unless it's in a garbage bag.

Does anyone know, if there's a brand of PSU that uses a new style of cap that will never bulge or leak.
One motherboard manufacturer claims to have such capacitors. Supposedly Good for the Life of the board.

**shovenose** · 11-26-2011, 10:58 AM

Re: Capacitor Lifetime

Actually mine was a Bestec 300-12Z turns out. I replaced it with a 250W LiteOn because I figured I didn't need 300W in a simple dual core. No bulging caps in my Bestec, but that's because a while back I replaced the bulging capacitor in it. It's a pity that they used such junk caps in the PSUs because they're not so bad as long as the caps haven't died.

**PCBONEZ** · 11-26-2011, 11:55 AM

Re: Capacitor Lifetime

Originally posted by ThePCDoctor

Does anyone know, if there's a brand of PSU that uses a new style of cap that will never bulge or leak.
One motherboard manufacturer claims to have such capacitors. Supposedly Good for the Life of the board.

Good Japanese Lytics are good for the life of the board too.
.
Those 'new' caps are called Solid Polymer and they aren't even close to being new.
I have a retired Intel PII sever board from 1998 that is 100% solid polymer.
What has changed is that in 1998 Solid Polymer caps were probably around $15-$20 each.
That board's MSRP was $899 in it's day.
.
[If ever] you aren't likely to see a 100% polymer ATX PSU for another 5 to 10 years.
There are some caps in PSU's [namely the primaries] that Polymer technology can't even touch yet.
.
I did see a partial poly atx PSU somewhere or other but the price was so ridiculous I didn't care to commit it to memory.
.

Capacitor Lifetime

Capacitor Lifetime

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Related Topics