Super Caps as BCR

Yep, you need a low ESR for it to be able to deliver enough power to power the board during power interrupts or during shutdown.  What is the specific capacitor you use? 

This AVX SCMR22C155MSBA0 has a 120 mOhm ESR and will deliver several hundred milliamps without much of a voltage drop.  However, this Panasonic EEC-S5R5V155 has a 30 ohm ESR and could only deliver a few milliamps before excessive voltage drop.

If you use the right supercap, you'll have no problem.

If thats the case mine should work. Its an AVX SCMR22F155MRBA0.

ESR is 200mOhms.

Pete

After the charge-up interval, if you remove track power do the 5-10 sec shutdown sounds play to completion?  That's a good indicator that the cap is charged.

If you're not getting full shutdown sounds, if you can access the supercap when installed, measure its voltage.  It should be close to 5V.  OTOH, the dual-AA/AA battery pack only charges to ~2.4V.  This "quirk" in charged-up voltage is critical for the PS2-3V supercap to work.  In contrast, in the PS2-5V board set, the charged-up voltage for the battery version and the supercap version are essentially the same (~8.4V).

I am using the Digi-Key 478-10023-ND, 2.5F,  75mOhm@1kHz and am having good results after initial charge.

I have a big articulated, PS2 locomotive that can sit for over 1 week without being run and it starts right up with no degradation or reduction in sound, etc.  Performance is good.

Should I stay with it?  or upgrade to the 120Ohm ESR?

bruce 

bruce benzie posted:

or upgrade to the 120Ohm ESR?

That would be a downgrade.  In re super cap ESR, less is more.

If the one Bruce is using is the same as the one GRJ recommended a year or so ago, that's what I've been using in some 20 locos with no problems.

stan2004 posted:

bruce benzie posted:

or upgrade to the 120Ohm ESR?

That would be a downgrade.  In re super cap ESR, less is more.

Thats what I would have assumed though when I ordered mine I didn't even take ESR into consideration.

BTW all other functions are normal including shutdown. Only chuff seems to be affected.

Back to the drawing board.

Pete

Norton posted:

 

...BTW all other functions are normal including shutdown. Only chuff seems to be affected.

 

So when you lose chuff sounds,

- the engine speed does not hiccup, jerk, whatever?  It continues running smoothly at the commanded speed?

- if smoke is turned on, if you run slowly (where you get distinct puffs) do the puffs occur when you'd expect the chuffs...like 4 puffs per driver-wheel revolution?  

Speed @ 1-2 mph is jerky even with the battery. Smooths out above that. I do lose smoke with chuff. Actually when I get no chuff I shut down after running a few inches. I know its not right. Sounds like an ESR issue. I may first try to parallel a few of these to verify before ordering something else.

Pete

Norton posted:

...Sounds like an ESR issue. I may first try to parallel a few of these to verify before ordering something else.

As you know, you can operate a PS2 engine WITHOUT a battery installed.  It won't handle track-voltage dropouts, won't save/retain any changes to setting, and such...but perhaps you could run the engine on its side (or whatever) with clips directly to the center roller and chassis to "guarantee" good contact.

It's as if the mere presence of the supercap (charged or uncharged) is dragging down the power supply to the tach...whereas the battery does not.  I suspect your chuffing will work fine with nothing connected to the battery connector; I suggest this since it is a quick experiment...

Stan, while you were posting I was paralleling two of my caps. Seemed to have cured the problem. After a dozen or so startups and shutdowns including turning track power off it now starts and chuffs as with the battery.

I know no battery means I have to find the engine each time. I will keep testing this engine before converting anymore of my engines. At least my investment won't be a total waste.

Pete

Norton, I replaced all my PS2 batteries with 2.5F supercaps over a year ago.  I have found no operational differences, and have no idea what you mean by having to find the engine each time.  I did buy a new PS2 loco back about 2010, that had a defect in that it would not hold a setting.  MTH fixed it under warranty.  You may have had a component failure

I did find one VERY rare occasion when there is a difference.  I often hit startup right after powering on a track, so supercap hasn't charged up.  If track power is cut (as when a grandchild leaves a car derailed and doesn't tell me, causing breaker to pop when train moves) before it has charged, loco ID can be garbled.  Same thing happens if a battery is dead.

"Having to find the engine each time" was a reference to what Stan said about running with no battery or BCR.

Pete

I guess I was not clear.  Running with no battery was meant to be a 1 minute experiment to help troubleshooting.  

What about soud volume?  Are you running this in conventional?  I have not seen the supercap effect any other operation if the PS-2 3V board charging circuit works....Charge capacitor and kicks it in an out with direction changes. G

G, there were a few times when sound was lower but then came back to normal.

I have pretty much come to the conclusion that the supercaps I picked were not ideal. Paralleling two of them seems to have solved the problem.

I now have 3 farads @ 5.5 volts. Not sure if ESR is cut in half from 200 to 100 mOhms. May do some testing to verify ESR.

Anyway The ones I bought won't be wasted and my next batch will be different.

FYI I run these in Command. 

I didn't do any real research on these before ordering and have no BCRs to test so I was just shooting darts. That said I find I learn more when something doesn't work then if it does.

Thanks everyone for their input.

Pete

I have these in a RK steam and a Premier diesel, both PS2 for two years with no problems at all

The one John show is what I use.  The 1.5 F work too, just a little less stored energy.  The 2.5 work well.  When new and first power applied they will be at zero voltage and require full charge from PS-2 board.  The board senses this low voltage and high demand on the 5V power supply and the processor trys to reduce demand by signaling audio to half power.  That is why sounds start loud at startup, but once startup sequence complete the audio drops off.  Once capacitor get above 2 plus volts charge the processor sense a sufficient voltage on the power supply with manageable current draw and will restore volume to full or set volume.  At that point you can start operating train in conventional.

Once initial charge is on capacitor, even if you shut down for a day or 2, this process occurs pretty fast with a good power supply board.

There are damaged power supply board that can charge a battery or super cap, but at a reduced rate.  The Fet is damaged and it can take 5 mins to charge the cap.  A good power supply takes about 30 secs or less to meet nominal charge.  G

I was wondering about the condition of the power supply board. This engine has an upgrade kit thats about 5 years old and only gets run occasionally. When I charged the cap on the bench with my lab power supply it charged almost immediately to 4.1 volts 

After two days it was still reading 2 75 volts.

Anyway now with dual supercaps it works every time. Next time I will probably go with the one "Upstate" (aka neighbor) John H showed above. I like the specs.

Pete

Credit for the supercap goes to Gunrunnerjohn, as I used his recommendation from a previous thread.

That was the cap I chose...long time ago in a distant galaxy :-) G

What would be that date?

Casey Jones2 posted:

What would be that date?

 

1817. The good doctor is getting ready to energize the first super cap.

Pete

Casey Jones2 posted:

What would be that date?

 

After you picked the 1.5F version.  I settled on the 2.5F.

The first caps I used were the 2.5F ones that John posted.  I got a really good deal on 1.5F caps and tried some of those, they seem to do the job as well.

GGG posted:

Casey Jones2 posted:

What would be that date?

 

After you picked the 1.5F version.  I settled on the 2.5F.

I received a cease & desist email over those from J&W as he claimed he held a patent on them. I laughed as his patent was for the BCR...not the BCR2 

You can make all of these you want for private use, including 9V BCR clones.  You just can't sell them if they have a patent on that specific design.  It's pretty hard to patent a single component that already exists.