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.