Reply to "Replacing Batteries with BCRs in MTH PS1 and PS2 Locomotives"

I thought I would kick this old topic back into gear, found it by a search, where there is a lot of info available.  I finally acquired a MTH B&O Doodlebug at a great price, and the battery in it was discharged to about 6 volts, didn't want to see if it would hold a 9 volt charge so and instead of getting a new one, I wanted to go with a BCR.  BCR's are expensive in ready to go 9V versions and some individual farad size capacitors can also be pricey.  I found these at Newark Electronics for around $1.80 each in lots of 10 to 20, and the price drops as you buy more.  These are 1.5 F at 5.5 volts.  Being that they are from the same manf., I put faith in the fact that they could be put in series without getting complicated with the balance circuits you see advertised for series connected batteries. I had thrown away my dead 9 volt batteries, where I should have held on to a few to extract the connector plate, but I have a bunch of 9 volt battery clips that I use to build 45 volt B batteries for vintage radios.  I put about 1/2" of shrink tubing on the 9 volt clip wires, and soldered the red lead to positive, and black to negative, close to the capacitor, trimmed the leads and pushed the tubing over the solder joint and shrunk the tubing on.  In this particular engine, I needed to put the 2 caps one above the other, and got them close enough to equal the length of a 9 volt battery.  I twisted the bare negative lead of one, positive lead of the other together, soldered, and trimmed the lead, bent in between the 2 capacitors, without touching either battery.  I did not have a large enough shrink tubing to fit the caps, so I used a couple turns of electrical tape to hold them together.  A trick to electrical tape is you can wrap it tightly, but the last turn or two, do not keep under tension, such as pulling the tape to break it instead of cutting, or that last wrap will slowly creep back and come loose.  The new BCR's fit in the battery compartment and the battery clips fit alongside.  When all power is cut, the loco continues to make sounds for about 8 seconds. Just one of these capacitors are good for 3 or 5 volt replacement BCR's.  These capacitors are Cornell Dubilier P/N DGH155Q5R5, Newark P/N16AC9322.  There is one caveat to these though.  With your loco on the track in neutral, and full track volts applied, check the voltage coming from the battery charger circuit and make sure  it is close to the battery voltage, a Nicad 9 volt battery puts out 8.4 volts, so you would expect a charge voltage in the 9.5 volt range.  The 3 volt battery is 2.4, 2 cells in series,  and the 5 volt with 3 series connected cells is 3.6 so any charge voltage much above 3 or 5 is suspect.