Quick charging and testing of BCR2

An unregulated DC power pack could damage the BCR2.  A current regulated 10VDC battery charging source is recommended.

Thanks again Steve (don't you ever sleep, cause I know it is nighttime over there in the US right now)

What exactly do you mean by a "regulated current limited" transformer????

Aren't all HO Gauge DC transformers created equal??

Peter.....Buco Australia.

I mean a correct battery charging circuit.  Unless I'm mistaken about BCR2's (which are somewhat new to me) ... if they're anything like capacitors and batteries... when they're fully discharged and you first start charging them, they will draw a lot of current initially.  Allowing electrical storage devices to draw too much current initially creates excessive heat in it.  Too much heat = damage.

Eventually though, as the charge increases (voltage across the BCR2) its current demand decreases.

I hope that makes sense.

Puzzled. Why do you want to charge them outside of the engine? Just curious.

Yes, it does make sense Steve.

Kinda thought that the BCR2 starts charging (when installed inside a loco/tender) when I switch on my DCS Remote Commander (19VAC) and wait for one minute, while the loco sits on the tracks. The bridge rectifier on the PS2 board converts the incoming AC into DC, and then into the charging circuit of the battery/BCR.

If the DCS Commander can supply the umph to charge the BCR at 19VAC, I suspected my Distiller DC hobby transformer (0-18VDC) should be able to get the BCR up and running.

The only thing I was aware of, is the need to apply DC power to the BCR, as it is a "battery",  when all is said and done.

As they say in the classics.......try it and find out!!!  What have I got to lose.....one crappy DC transformer that never gets used anyway, and possibly a fried BCR2 (I make them easily for around $8 each).

Watch this space Steve......

Peter.....Buco Australia.

Jim @Jim 1939

I make my own BCR's (way to expensive to buy them in the States and get them shipped to me here in Australia now), and when I am finished, I want to test them to make sure the supercap is up to the task.

In the past I have found a very small number of these supercaps will not take a full charge, or they lose their charge within minutes of the charging cycle.....these I class as "duds", and they get discarded.

I buy them in lots of 50, and they work out at under $8 each Australian ($4 US), delivered.

Hence my need to "test" them before they go into a loco.

Peter.......Buco Australia.

Peter, maybe consider waiting until @gunrunnerjohn, @Vernon Barry or another more knowledgeable electronics person weighs in here, but I'm pretty sure there's a current limiter either in the locomotive or PS2 wall wart charger that safely charges the battery/BCR.  Just guessing, but it may be best to use a DC power source that's limited to probably less than 1 Amp.  Using a more powerful HO DC power pack may "work", but if my hunch is correct, the damage to the BCR2 may not be readily apparent and would theoretically manifest as a long term inability of the BCRs to perform optimally.

If it was me, and I wanted to do what you're doing, I'd first ask here (like you are)  and wait for a more definitive answer.

You could build a charging connector that plugs into the charging port of a PS2 3 volt engine using two prewired molex connectors like these:

One end will plug into the locomotive and the other into the BCR2.

This way the engine can charge the BCR2 outside of the loco without taking the shell off.

I use a current limited supply to test supercap battery replacements.  I limit the charge to 100ma, but it's safe to increase that to probably an amp if you like.  I don't recommend trying to apply unlimited amps to a supercap, it appears as a short circuit when fully discharged and will likely overload the P/S and could overheat the supercap.  The ESR of the supercap determines the maximum current if you have an unlimited current power supply, A typical ESR for the type of caps we use for a BCR clone would be in the 100-200 milli-ohm range.  Given that rating, if you apply 5V to that fully discharged supercap, you have a possible 50 amps of current if the P/S could supply it.

Would it be OK to use the 3 volt ( two pin ) MTH charging wall wart for the BCRs ,GRJ ?

Thanks for the electronic lesson John @gunrunnerjohn, but unfortunately most of it went straight over my head 😢

I was looking for a quick and easy way of externally charging the BCR's, and then testing them with the multimeter to to make sure they are working/holding their charge, before I send them off to my "mates" here in Australia, who also have MTH trains.

John- I am interested in the solution suggested by @H1000 - not sure how/if this could work, but I know I can make the double-ended Molex plug lead, and give it a try. Not sure if the external (test) BCR can get power from the loco/tender (that already has a BCR installed in it) to initiate the charging phase for both BCR's.

What do you think??

Peter.......Buco Australia.

Peter, Maybe a relatively simple and inexpensive stand-alone charging solution would be to use the plug @H1000 showed connected to one of those ubiquitous small 5Volt USB (1Amp) phone charging blocks (not the bigger 2 Amp variety used for tablets).  The small block limits the current to what may be a safe charging current for the BCR2.  What do you think @gunrunnerjohn?

@Dallas Joseph posted:

Would it be OK to use the 3 volt ( two pin ) MTH charging wall wart for the BCRs ,GRJ ?

Sure, those are current limited to a pretty low current, probably not more than 30-40 ma.

Be careful what loco you might want to replace the battery with a BCR.  I have run across one older P1 MTH that the BCR burned up a resistor that was in the circuit to the battery.  Thankfully, it was on the edge of the circuit board and could easily accessed to be replaced, but I left that one with the battery.  I have been testing any loco I want to swap battery with BCR ever since, reading the initial current surge with an DVM  with a peak and hold function to capture the max it draws before committing to the replacement.

If I am reading it correctly, the option provided by Dallas @Dallas Joseph is to use the MTH RailKing Battery Charger for PS2 3V loco's that still have 2xAA or 3xAAA batteries fitted to them .

I just plug the "wall wart" into the 110V supply outlet, and then plug the white two pin Molex fitting into the lead of the BCR2??

When charging a BCR2 that is already fitted to a loco, I just wait 60 seconds with full track power on (19-20VAC), and then start pushing the + button on the hand-held remote to get the loco moving, and the BCR is charged in that one minute timeframe......right?

How long would I have to keep the MTH RailKing Battery Charger attached to the BCR lead, to get it fully charged.....one minute, one hour, one day????

Questions, questions, questions.......sorry, but I don't want to willingly damage any of these precious components.

Peter......Buco Australia.   

Peter , I'm not sure what the time frame for getting the BCR2 to a fully charged state with the wall wart would be.

   I've never done a charge on a BCR2 outside of the locomotive . I have left the MTH stock battery pack charged on the wall wart charger for a very  long time and I have never felt the batteries nor the charger getting hot.  When I check the battery pack with my VOM I find it to be well charged.    I don't know if there is some safety overload system involved or not.

All my ps2 with BCR2s and my ps3 locomotives gettrack power for at least two or three minutes before I start them up......    Usually I dont get in a hurry and find a couple other things to do before the start up , sometimes for much longer than two or three minutes with no ill effect. ( the " cab chatter " can sometimes be annoying while I'm working on something else though  )

My track power is supplied by the Z1000 , TIU , and remote for The DCS full system.

Happy charging Peter.

BCR are charging in the 30 to 45sec range.  If you are using DCS you do not need to wait.  You can start the engine up and run it.

PS-3 supercaps start up in 10 sec or less range.  So they are letting them charge faster it seems.  G

@GGG posted:

BCR are charging in the 30 to 45sec range.  If you are using DCS you do not need to wait.  You can start the engine up and run it.

PS-3 supercaps start up in 10 sec or less range.  So they are letting them charge faster it seems.  G

Some really good info here from GGG , Peter.