Recapping PSU, low-esr or longlife caps?

[corliq]

If I am going to recap my PSU, should I buy the low-esr caps or the longlife type? I've checked the online store and the low-esr caps usually have 2000-hour at 105C but the longlife type usually have 8000/10000-hour life at 105C.

The capacitors I am going to replace range from 10-16v 1200-3900uF.

Thanks in advance>

[japlytic]

Re: Recapping PSU, low-esr or longlife caps?

I recommend capacitors with both long life and low-ESR characteristics.
Nippon Chemi-Con KY is rated at 4-10k hours and KZM is rated at 6-10k hours.
These values are rated for worst possible conditions i.e. at maximum ripple current and temperature.

[corliq]

Re: Recapping PSU, low-esr or longlife caps?

Thanks for your suggestion.

[370forlife]

Re: Recapping PSU, low-esr or longlife caps?

If I am going to recap my PSU, should I buy the low-esr caps or the longlife type? I've checked the online store and the low-esr caps usually have 2000-hour at 105C but the longlife type usually have 8000/10000-hour life at 105C.

The capacitors I am going to replace range from 10-16v 1200-3900uF.

Thanks in advance>

Usually that life is based on constant use under the worst conditions the cap is rated for. A 2000 hour cap at 105C will usually go 6000 or so at 40C.

[PCBONEZ]

Re: Recapping PSU, low-esr or longlife caps?

You are confused by the name of the characteristic in the data tables.
Not to worry. Everyone is at first and obviously some old guys still are.

The term "Lifetime" doesn't have anything to do with how long a cap is expected to last. The proper name is "Endurance Lifetime"

What it actually tells you is:
- how long the cap can operate at max rated: volts, ripple, temp, and rated frequency [all at the same time]...
... AND NOT cause ANY of the values [uF, ESR, leakage] to go out of spec.

It's how long you can abuse a cap WITHOUT damaging it.
It tells you nothing about how long a cap will last in a real world application.
That's simply not what it is.

No manufacturer makes claims about the "Useful Lifetime" or "Expected Lifespan" of their caps.
There are too many variables and they don't want to get sued.

It should be obvious when you look at better grade higher quality caps that that number is useless.
Look at Rubycon MBZ or MCZ and you see the Endurance Lifetimes [A.K.A. "Lifetime"] is only 2000 hours.
2000 hours ~~> 83 days.
If you actually believe the average MBZ only lasts 83 days 'real world', you're nuts.

History shows that quality caps that aren't abused easily last 8, 10, or even 20+ years...

There are equations that approximate the Expected [Actual] Lifetime based on the Endurance Lifetime but they are only +/- 40% accurate. If the math shows 5 years it really means 5 years +/-40% which is 5 +/-2 years or "somewhere between 3 and 7 years". In other words the equations have so many inaccuracies they aren't worth the trouble to do the math.
- As such,
- Realistically the "Lifetime" shown in the data tables is not useful information and can be ignored.

Buy quality caps and don't get your knickers in a twist over "Lifetime" numbers shown in data tables.

- Worry about the ESR.
The lower the ESR the cooler the caps internal temp will be and internal temps have a HUGE affect on how long caps will last. [It is the biggest factor in those equations I just mentioned.]
- Lower ESR -> Lower internal temps.
- A 10C reduction in internal temp doubles a cap's Lifetime.

ESR is -WAY- more important as to how long a cap will actually last than Endurance Lifetime is.

.

[370forlife]

Re: Recapping PSU, low-esr or longlife caps?

Hey pcbonez is back.

I need to watch my math. 6000 hours is only 250 days

[i4004]

Re: Recapping PSU, low-esr or longlife caps?

>If I am going to recap my PSU, should I buy the low-esr caps or the longlife type?

essentially without measuring ripple(and you need load tester for that) you can't tell how will your psu react to lower esr ie different esr.
http://www.jonnyguru.com/modules.php...rint&ndar_id=8
see "page 4".

if you have a psu that you know has good and clean output, then just try to match the caps you already have there....better to say match their characteristics when they were new.

if you don't know how was the output of the psu to boot, i would say get a decent psu, don't bother, because you may end up with worse psu than you started with, as jonnyguru's article shows.

overall, i wouldn't put low-esr cap in the psu that previously didn't had them, because it seems design counts on some esr for proper functioning.

as for how long will they last: i would say it's easy...good quality caps last more than crappy leaky chinese garbage...heh...
good quality caps(regardless of the type) last more than is the usefull life of the psu, so you don't have to worry about that.