BCR Life Expectancy?

More likely it's a bad solder joint somewhere in the package.  But yes caps do fail from time to time.

Superwarp1,

   You are definitely correct a supercar can go bad, however I have some that are now over 15 years old that still work perfectly.  I agree with the bad solder joint analysis also, more than likely that is the problem some place.

PCRR/Dave

If it's the 9 volt style check to see if the BCR's terminals are still fully seated and attached.  I had an early 9 volt type BCR that I purchased new at York from JWE which had one of the top terminals slightly disconnected from its innards/case.  I contacted JWE within the week and they were excellent; sent me a free replacement.  They said I didn't need to return the broken BCR, but the next show I gave them the defective BCR and thanked them for their good service.

Thank you for your replies, It just seemed strange that I would have 3 that started failing within 4 weeks.  But replacing them seems to resolve the issue, go figure.

FWIW, the capacitors used, the EDLC caps do have a finite life.  They have an MTBF of in the 1,000-2,000 hour range.  So, after a long time, they may indeed start failing, and many charge/discharge cycles will speed that process up.

Super caps last a life time and don't fail like just like LED's vs. lamps.  They are not like the old conventional caps which swell and fail due to cycle, age and heat.

No worries here, I have 4 in operation for several years now and 12 more in stock ready to retrofit should I need them. 

If you experience a failure , it's most likely been self induced by operator error.

SIRT posted:

Super caps last a life time and don't fail like just like LED's vs. lamps.  They are not like the old conventional caps which swell and fail due to cycle, age and heat.

That would be a false statement.  Don't fool yourself into thinking that wet electrolytic capacitors of any type can even come close to the MTBF of LED components!

Here's one convenient calculator: Capacitor Life Calculators

From that page, here's a basic description of the life factors.

Operating conditions directly affect the life of an aluminum electrolytic capacitor. The ambient temperature has the largest effect on life. The relationship between life and temperature follows a chemical reaction formula called Arrhenius' Law of Chemical Activity. Simply put, the law says that life of a capacitor doubles for every 10 degree Celsius decrease in temperature (within limits).

Voltage derating also increases the life of a capacitor, but to a far lesser extent, as compared to temperature deratings. Internal heating, caused by the applied ripple current, reduces the projected life of an aluminum electrolytic capacitor.

Using their SuperCap model, I calculated some MTBF numbers.  The Load Life rating, max temp, and rated voltage is for an actual supercap.  Notice how a 10 degree rise in the ambient cut the MTBF in half.  Also, MTBF is an average, not a minimum.  You'll experience failures well below that number as well as well above, remember the statistical bell curve.

Values underlined are my entries.  40C is a pretty close estimation of the temperature in normal operation, the 50C is for illustrating the effects of temperature.

Wow, I'm impressed.  I remember when I worked in the computer industry, and an accelerated MTBF would be disastrous.  On more than one occasion when we would peel back the onion, and find an extreme environmental situation was in place.  (ie operating equipment in a hostile environment.)  In any case the remedy of this situation is quite simple, easily resolved.

I really appreciate the time and consideration provided, Thanks  

Store your trains in your liquid nitrogen tank   ?      WHAuT ?   That's where I keep my potato chips, keeps them nice and crisp. 

     This does make one want to do a pole of how long folks have gone before their supercap battery replacement failed.   I have not been using them long enough to have had a failure.               j

Having worked in aerospace for many years, I got real familiar with component MTBF and it's effect on overall failure rate of a product.  I was by no means an expert in that field, we had people that did that as a primary job, they were more like accountants than engineers, they just sat and crunched numbers most of the day.   Our job was to find a way around problem component's effect on overall MTBF.

These hours of derating life expectancy, are "under load" hours, correct.   So is shelf life before and between load hours a factor ?  Should we put our BCR's in the freezer ? Or in an oven ? Or just OK on the shelf at room temperature?

Its all interesting info. As I have encountered over 42 years, what was, may no be applicable in todays times. Your data and observation would most likely be accurate, however….Since the use of our application is in a non-industrial toy train micro circuit operating at low voltage and temp conditions, I’m not anticipating any failures. 

Besides, time wise, we would never see or reach the maximum life of the component specs by operating each engine.

As I think about this, I am more concerned about the acid from RTV that I used eating the 2 leads  holding the part in place. I may have to inspect that. Hope it was the non-corrosive type.

Thanks for the info. I’ll let you know if I do have one fail and maybe we could figure out the root cause? 

Wet capacitors dry out on the shelf, but at a much slower rate than under power.  The temperature is all important, if you store them in the oven, they'll die quickly.

SIRT posted:

Its all interesting info. As I have encountered over 42 years, what was, may no be applicable in todays times. Your data and observation would most likely be accurate, however….Since the use of our application is in a non-industrial toy train micro circuit operating at low voltage and temp conditions, I’m not anticipating any failures. 

Besides, time wise, we would never see or reach the maximum life of the component specs by operating each engine.

As I think about this, I am more concerned about the acid from RTV that I used eating the 2 leads  holding the part in place. I may have to inspect that. Hope it was the non-corrosive type.

Thanks for the info. I’ll let you know if I do have one fail and maybe we could figure out the root cause? 

You're probably right, just wanted to point out that the MTBF of caps is not as good as an LED.  However, I've had LED failures, but I'm sure most of them will outlast me.

I have looked a bit but yet to find.  Are solid polymer AL. e-caps available in supercap values 1~2f ? They have a much greater shelf life than conventional wet electrolyte caps. Some computer board mfgs claim unlimited shelf life for these solid electrolyte caps.     j

The whole bit with supercaps is the unique construction, I never heard of a dry electrolyte version, I suspect it's not yet possible.

A nagging question,  Is it feasible to put a BCR in Lionel engines, (TMCC or Legacy)?  It would be necessary I suppose to be 9v equivalent?

Hmmm

After reading my own post above, I think it is probably a dumb question.  Lionel is NOT using any Ni-Cad batteries, therefore it doesn't have a recharging circuit, and wouldn't have a means of charging up the BCR.

You speak too soon Don.   There is indeed a supercap product for Lionel locomotives.

 YLB - RailSounds Battery Replacement

YLB Documentation.pdf

John,  No kid'n!  That looks really great, a little pricey, but definitely worth it.  I haven't had much of an issue with 9v batteries leaking, just lucky I think.  I believe I'm going to go ahead and get them for my more expensive engines.

Surprised no one has come up with how to make your own yet.

Thanks a lot!  This in it self made this whole thread significant to me.  Much less how much I've learned from the above conversations.    

I can tell you why nobody came up with a DIY solution, it's not quite as simple as the BCR.   There is actually a lot of circuitry inside the package, which also explains why it's a bit more costly.  In addition to the supercap, there are actually two power supply circuits, one to charge the cap to 5V, the other to boost the voltage to 8V for the RailSounds board.  This was necessary to squeeze as much energy out of the supercap as possible.  It even includes the choke for DCS compatibility so it won't step on DCS signals.