Could I have bought a new "bad" BCR ?

I use BCRs, but I'm not an expert on their usage.  Some thoughts and suggestions...

Doubt that you fried an engine by installing a BCR - they're just capacitors and are basically plug and play.  But perhaps a wire was pinched or pulled loose when reinstalling the shell.

To help the experts, I'd suggest posting model numbers of the engines you're dealing with along with a description of how you're applying power and details regarding the behavior they're exhibiting. 

I have had a similar experience to what you're describing where it's hard to tell if the BCR isn't working or if the engine was fried prior to install. I never did solve it and just figured I was inexperienced and had to learn more before I could figure it out.

In a word yes; I contacted J&R, and received a replacement 9v style red BCR free of charge, mailed at their expense.

You would know if the BCR had fried it. Smoke and lots of it.

I had an incident with an EP 3, MTH 20-5558-1, which I purchased seemingly unused. Powered it up, determined the battery was completely done, installed a BCR 3 volt, and everything went south. Got it repaired by replacing the board with an upgrade. George said the 3 volt board was shorted but didn't find any obvious cause. I understand what folks say about the BCR, but next time I'm doing nothing until I put in a new, charged battery.

Opinions vary on whether the BCR can damage things, but I will point out one fact.  A BCR (supercap) looks like a direct short when you first turn it on, and so it does put a much larger load on the charging circuit until the cap gets at least a partial charge on it.  As to whether that is detrimental to the charging circuit remains open to conjecture.

I personally think a good design of a battery replacement would add an inrush limiter to allow the capacitor to charge more slowly without putting an excessive load on the charging circuit.

I've seen a couple 5V boards that apparently bit the dust right after installing a BCR.  However, 5V boards have a reputation for biting the dust if you look at them funny, so it's hard to say if the BCR figured into the failure.  I've seen plenty of 5V boards bite the dust with no BCR in sight, so there's that...

Battery Capacitor  Replacement with Inrush Limiter Technology will probably be gunrunnerjohn's next available product, if we're lucky!😁

@gunrunnerjohn posted:

Opinions vary on whether the BCR can damage things, but I will point out one fact.  A BCR (supercap) looks like a direct short when you first turn it on, and so it does put a much larger load on the charging circuit until the cap gets at least a partial charge on it.  As to whether that is detrimental to the charging circuit remains open to conjecture.

I personally think a good design of a battery replacement would add an inrush limiter to allow the capacitor to charge more slowly without putting an excessive load on the charging circuit.

I've seen a couple 5V boards that apparently bit the dust right after installing a BCR.  However, 5V boards have a reputation for biting the dust if you look at them funny, so it's hard to say if the BCR figured into the failure.  I've seen plenty of 5V boards bite the dust with no BCR in sight, so there's that...

I recently had an issue of a shorted board on a Premier ps2 /3 volt.   The engine was purchased on the Bay with a Popular supplier's BCR2 installed.   It ran for some time until recently.  On start up now the only life it shows is a faint buzzing noise from the tender. 😣

The negative shrink tubing and black wire insulation coming out of the BCR2 had melted to the OUTSIDE of the male connector from the speaker wires.  I didn't see any bare wire from the BCR2 negative side but it must have been pretty hot.  Also a red charging circuit wire connected to the BCR2 had melted itself to a larger gauge orange wire with no continuity established between the two.

I found there to be continuity between the pins on the removed BCR2 and another one that I had from the popular supplier.   I also found the same result with one that I had from you.  So I figured things should have been OK .

JUST A COUPLE QUESTIONS John :

1.)   The BCR2s from the popular supplier are rated at 5.4 v and your caps is rated at 5v.   Any significants reason?

2.)    Is there a different connection that I should make with your caps with the MALE connector end instead of the FEMALE end found on the other BCR2s ?

AND FINALLY.......the only place I could find an issue with the tender itself was that one wire had broken loose at the speaker .  I couldn't say if it may have contacted the metal speaker housing or not. 🤔

Thanks John.

@gunrunnerjohn posted:

Opinions vary on whether the BCR can damage things, but I will point out one fact.  A BCR (supercap) looks like a direct short when you first turn it on, and so it does put a much larger load on the charging circuit until the cap gets at least a partial charge on it.  As to whether that is detrimental to the charging circuit remains open to conjecture.

I personally think a good design of a battery replacement would add an inrush limiter to allow the capacitor to charge more slowly without putting an excessive load on the charging circuit.

I've seen a couple 5V boards that apparently bit the dust right after installing a BCR.  However, 5V boards have a reputation for biting the dust if you look at them funny, so it's hard to say if the BCR figured into the failure.  I've seen plenty of 5V boards bite the dust with no BCR in sight, so there's that...

My education in electronics for trains marches on.

Just wondering, and please excuse my ignorance if this is a dumb idea, but would it be possible to add something like this to the connection to the BCR?  Saw a price of only $1.30 each.  https://www.amphenol-sensors.c...-web.pdf?Itemid=7968

And if it would work, should it be connected to the positive or negative, or does it not matter?

@Mallard4468 posted:

My education in electronics for trains marches on.

Just wondering, and please excuse my ignorance if this is a dumb idea, but would it be possible to add something like this to the connection to the BCR?  Saw a price of only $1.30 each.  https://www.amphenol-sensors.c...-web.pdf?Itemid=7968

And if it would work, should it be connected to the positive or negative, or does it not matter?

This looks interesting sir. 🙄

@Dallas Joseph posted:

JUST A COUPLE QUESTIONS John :

1.)   The BCR2s from the popular supplier are rated at 5.4 v and your caps is rated at 5v.   Any significants reason?

2.)    Is there a different connection that I should make with your caps with the MALE connector end instead of the FEMALE end found on the other BCR2s ?

AND FINALLY.......the only place I could find an issue with the tender itself was that one wire had broken loose at the speaker .  I couldn't say if it may have contacted the metal speaker housing or not. 🤔

The speaker wire being loose wouldn't cause a meltdown of the connection to the supercap, but it could kill the PS/2 board.  I'm hard pressed to think of anything that would melt the cap wire unless somehow a wire on the cap itself contacted the frame.

1. Virtually all the 5V supercaps are constructed the same way, with two 2.7V 3F radial supercaps.  Some makers are conservative and rate them at 5V to allow for a minimal unbalance in charging the two caps in series.  Others just add up the 2.7 ratings and rate them at 5.4V.  The charging circuit on the 3V boards peaks at 5V with no load as it's fed by a 5V regulator.  You'll notice the major brand name caps like AVX use the conservative rating of 5V, and the cheap no-name knockoffs tend to use the more "pushing the limit" rating of 5.4V or 5.5V.  I consider any of these to be 5V caps.
2. I made some caps with the JST-PH connector that mates directly with the top board of the PS/2 3V battery connection.  I've also just whacked off the leads from a dead battery pack and made them that way.  Connect them to the place the connector fits.

Here are the two different styles of 3V supercap replacements.

@Mallard4468 posted:

My education in electronics for trains marches on.

Just wondering, and please excuse my ignorance if this is a dumb idea, but would it be possible to add something like this to the connection to the BCR?  Saw a price of only $1.30 each.  https://www.amphenol-sensors.c...-web.pdf?Itemid=7968

And if it would work, should it be connected to the positive or negative, or does it not matter?

The selection of the inrush limiter is a bit more sophisticated than just grabbing one from the shelf.  Check the second page for the selection criteria for picking the device.  If you look at the table, you'll see that none of those devices are suitable for this application as the steady state current is more like 150-200 milliamps, not amps.

Correct me if I am wrong, but super caps have an impedance rating too.  The MTH charging circuit does have current limiting.  There are thousands if not tens of thousands of PS-1, 2 boards using BCRs out there.  So I think there would be a much higher failure rate if this was BCR related.

I just repaired a 2000 PS-1 engine with original white battery.  Had a motor driver issue, but it actually still came out of reset and ran.  Just did not get the 2 dings at startup.  Go figure.  With new battery or BCR you got the startup dings and it runs fine.

Back to the PS-2 3V, I am one of the few that knows how to take measurements on the 5V and 3.3V power supply buss, and from static measurements can determine types of failures.  Years of backward engineering and troubleshooting to figure it out.

Hardcrabs Power Suppy board was good hence the BCR did not have anything to do with his failure.  The Processor 3.3V buss was bad though. Charging signal good.  So something just failed on the processor side.

I think we have entered the realm of the 3V boards having age related failures.  I seem to be seeing an uptick of processor failures.  G

@GGG posted:

Correct me if I am wrong, but super caps have an impedance rating too.  The MTH charging circuit does have current limiting.  There are thousands if not tens of thousands of PS-1, 2 boards using BCRs out there.  So I think there would be a much higher failure rate if this was BCR related.

I just repaired a 2000 PS-1 engine with original white battery.  Had a motor driver issue, but it actually still came out of reset and ran.  Just did not get the 2 dings at startup.  Go figure.  With new battery or BCR you got the startup dings and it runs fine.

Back to the PS-2 3V, I am one of the few that knows how to take measurements on the 5V and 3.3V power supply buss, and from static measurements can determine types of failures.  Years of backward engineering and troubleshooting to figure it out.

Hardcrabs Power Suppy board was good hence the BCR did not have anything to do with his failure.  The Processor 3.3V buss was bad though. Charging signal good.  So something just failed on the processor side.

I think we have entered the realm of the 3V boards having age related failures.  I seem to be seeing an uptick of processor failures.  G

Supercaps do have impedance, but typically the ESR of the caps we use are in the 100 to 300 milliohm region, so slamming them with 5V if it's not current limited can cause a demand of many amps of peak surge.  Here's the specs from the NESSCAP 5V 1.5F cap, one that I've used for years.  It's similar to most other comparable 5V supercaps.

As for charging current, let's do a test...

I set my bench supply to 2A current limit and 5VDC output.  I connected it to a fully discharged 5V 1.5F supercap I use for battery replacements and enabled the power output.  The current pegged at 2 the amp limit for several seconds as the voltage ramped up to 5V output before it dropped below the 2A limit.  I'm pretty sure the PS/2 board isn't capable of pushing anything close to that kind of current to the battery as it takes it a lot longer to charge the supercap.

Yes there is current limiting on the board so it will not surge that current.  Similiar to the rating on MTH battery charger.  Additionally it is micro processor controlled as there is an inductor in the charge circuit too for the 3V board.  That is how the 2.4V battery is boosted to 5V when AC power turned off.  G

@gunrunnerjohn posted:

The speaker wire being loose wouldn't cause a meltdown of the connection to the supercap, but it could kill the PS/2 board.  I'm hard pressed to think of anything that would melt the cap wire unless somehow a wire on the cap itself contacted the frame.

1. Virtually all the 5V supercaps are constructed the same way, with two 2.7V 3F radial supercaps.  Some makers are conservative and rate them at 5V to allow for a minimal unbalance in charging the two caps in series.  Others just add up the 2.7 ratings and rate them at 5.4V.  The charging circuit on the 3V boards peaks at 5V with no load as it's fed by a 5V regulator.  You'll notice the major brand name caps like AVX use the conservative rating of 5V, and the cheap no-name knockoffs tend to use the more "pushing the limit" rating of 5.4V or 5.5V.  I consider any of these to be 5V caps.
2. I made some caps with the JST-PH connector that mates directly with the top board of the PS/2 3V battery connection.  I've also just whacked off the leads from a dead battery pack and made them that way.  Connect them to the place the connector fits.

Here are the two different styles of 3V supercap replacements.

Hey John.

This is the engine in question.  I never saw this arraingment of spaghetti before in a tender . 

There is the top board connection for the male end on your super caps.   As a matter of fact when I looked at the MTH photo of the top board it  (  with the black and red wires ) was clearly marked as a terminal for " BATTERY  " on a ps2/3volt.

Of course in the photo you can see that my fully charged green battery was connected to a splice with the other red wire going to a center rail pickup.

I am familiar with black wires to a wire nut and red wires to a seperate wire nut not this arraingment.  It is however a 2 rail / 3 rail  unit.

Besides the BCR wire mystery the DCS / POLARITY switch  was frozen in the DCS position . With a good amount of force I was finally able to break it free.  I did salvage an exact replica switch and reattached everthing.

Still buzzing.   This is the item.

Thanks for your input John.

If the battery lead is truly paralleled with the track pickup lead, that's clearly a MAJOR problem!  That can't have worked at all that way, that would smoke the PS/2 board instantly!

I can't tell from that rat's nest what is really connected to what in that mess!

@gunrunnerjohn posted:

If the battery lead is truly paralleled with the track pickup lead, that's clearly a MAJOR problem!  That can't have worked at all that way, that would smoke the PS/2 board instantly!

I can't tell from that rat's nest what is really connected to what in that mess!

WHOOPS...........my mistake John.     The battery lead is connected to a terminal that ends up at the battery charging port at the top of the tender.

@Dallas Joseph posted:

WHOOPS...........my mistake John.     The battery lead is connected to a terminal that ends up at the battery charging port at the top of the tender.

Right where it should be!