Replacement 2.4V Battery Packs For PS2

Dumb question, since you're assembling these, why not just use a 5V supercap and the same connector and never have to worry about the battery again?

Hi John,

What's even stranger, I have a draw full of caps:

50V 470umf; 35V 1000umf; 35V 22oumf; 35V 100uF; 2.5V 3.3F.

Will two 2.5V 3.3F connected in parallel work?

@Bobby Ogage posted:

Hi John,

What's even stranger, I have a draw full of caps:

50V 470umf; 35V 1000umf; 35V 22oumf; 35V 100uF; 2.5V 3.3F.

Will two 2.5V 3.3F connected in parallel work?

NO!  You need the 5V rating for the caps, that's why I use the flat 5V caps.

In order to use two caps like that, they have to be in series.  As long as they're from the same lot, you don't need any charging equalization, just connect them in series.

Thanks again John.

These work

https://www.ebay.com/itm/3-x-2...T283342/184288253768

Cut off the connector from the new battery,  plug it into the connector on the old battery ( to act like a heat sink and keep the

connector pins from moving ) and solder on the old battery pack connector to the new wires.

My limited understanding is that a battery is for a long term storage of a DC charge for a relatively long term discharge. In contrast, a capacitor is for a short term storage of a DC charge for a rapid discharge. If this notion is correct, then technologically, how does a capacitor replace a battery in a PS2 circuit?

The capacitors used are relatively new "Supercapacitors" which can hold a large charge for a long time without dissipating it.  They act more like a temporary battery and hold enough charge to make the system operate.

https://www.techopedia.com/def...30407/supercapacitor

The Kastar and Kruta AA and AAA packs work very well and hold their charge for a long time. They are available from Amazon singularly or in quantity.  I usually cut the end off the old battery and solder it to the new pack, observing the correct polarity. That, and the Tenergy low self discharge nimh 9v are installed in hundreds of locos I've serviced.

Thanks JET & Jon, I now understand what a supercapacitor is and why it can be a replacement for a battery. What is a suitable brand and source for 5V supercaps.

I buy in bulk as I use them in a couple of my electronic products.  I like the AVX and NESSCAP brands, they're real quality product with full datasheets available, something that many bargain supercaps lack.   I've used many of the "off" brand ones in the past, but I had some failures that soured me on bargain supercaps.  I've never had a bad AVX or NESSCAP supercap out of hundreds I've used, so I trust them more.

I used these:

IMO, 4F is overkill and puts more strain on the charging circuit during initial power-up than desirable.  I find that 1.5F at 5V is plenty for 3V PS/2 boards.  FWIW, that's also what the BCR2 uses for their cap.

Is this the correct one ?

Yep, those will work, not a great price, but that's small quantity pricing.

I read that it is necessary to reverse the polarity hookup of capacitors used to replace a battery. So in an MTH locomotive where red = + and black = - in the boards, the negative lead of the battery replacement cap connects to the red + wire on the board.  Is this correct?

I hope newbies are not scared off by this discussion thread. The cheapest, easiest, and most effective solution for a PS2 battery pack replacement is a plug-and-play BCR from GunRunnerJohn, J&W Electronics or VTHokies on ebay.

Yep, that's how to connect them.

Bruce, I have over 30 Rail King steam engines, a few diesels and several trolley cars that have Nicd batteries. BCRs would cost me north of $700, so my least cost option is to make my own replacements using supercaps. I am now doing locomotives per hour.

Gunnerjohn, thanks again. Your help and expertise are very much appreciated on my railroad.

Funny thing, I have a bunch of mine to replace the batteries in, so I spent an hour at the workbench and generated more battery replacements.   My 5V stable is slowly shrinking as the boards croak, so those will get PS32 boards.

Bobby,

I am sure someone will gladly give you a quantity discount! (I did only 15 engines)

Gunnerjohn,

I am envious of your skills. It would take me many hours, perhaps a day or two, to make the amount of battery replacements you made. My drawful of 2.5V 3.3F Caps is dwindling, so I need to buy a bunch of the 5V 1.5F Caps to keep my battery replacement project going. I am finding that my motive power fleet has more 3V PS2 than 9V PS2 which is a good thing. So far, I found one 9V Nicd with corroded terminals.

I occasionally find corroded terminals on the 9V NiCad batteries, a couple times I had to replace the battery cable.

As for making the assemblies, I just line up all the parts and don them assembly line style.  Trim all the leads the same, then do one soldering step, and the next, etc.

Since I have pre-made cable assemblies, the 3V replacements go really quickly, just trim the cap leads, slide the heatshrink on the cable, solder them, and hit them with the heat gun.

The 9V ones take a little more time, but not bad.

Here is my score card to date. 95% of my motive power now has supercap battery replacements, BCRs, BCR2s, Nimh 9v rechargeable batteries and 2.4V rechargeable Nimh batteries. I made one flub-up so far by connecting the (+) of  a battery replacement pack of two 2.5V 3F caps to the (+)  of the circuit boards. So my Rail King GG1 makes sounds, it lights up, but it does not obey the DCS handheld controller. I changed the polarity so the cap (-) goes to the board (+). Is my GG1 fatally damaged?

Has anyone ever measured the actual voltage that the PS2 5 volt and 3 volt boards, charging circuits, reaches once the caps are fully charged?

5V board about 12V.  3V board about 5V.  That's for the charging circuit and would be what is technically called the open-circuit charging voltage.

If rechargeable batteries are connected the battery "technology" limits the voltage to ~8.4V or ~2.4V.  The 8.4V rechargeable battery is effectively 7x generic 1.2V batteries.  The 2.4V battery pack is 2x generic 1.2V batteries.

For caps, 5V versions based on four (4) stacked (in-series) 2.5V supercaps usually have some kind of voltage clamping technology (e.g., Zener diodes) to limit the voltage across the individual 2.5V caps...so in round numbers the voltage should not exceed 10V.  For the 3V versions based on one (1) 5V supercap, the voltage charges up to 5V.

Thanks Stan

" I made one flub-up so far by connecting the (+) of  a battery replacement pack of two 2.5V 3F caps to the (+)  of the circuit boards. So my Rail King GG1 makes sounds, it lights up, but it does not obey the DCS handheld controller. I changed the polarity so the cap (-) goes to the board (+). Is my GG1 fatally damaged? "

Since nobody else has answered ( I know zip about DCS )  I would try to attach a properly charged battery or supercap and do a reset to factory defaults ( 1 horn, 5 bells )   If it doesn't work with your DCS controller you may want to try it in standard AC.