Small PS2 2.4 volt batteries

The BCR2 is probably the smallest, but is around $20 unless you roll your own as Gunrunner does.

Hook a battery to it with the shell off to load in the sound file and save an engine ID, then put a BCR in it. They're about 3/4" x 3/4"x 1/2".

The AAA work fine (BG-4000006).  I have them in stock.  The switchers and a few other used them.  MTH also used a few 2/3 AA in upgrade kits when the ran out of normal AA.  They will all work.  They have more energy than the BCR can store.  G

I had my Railking NW2 open this weekend and it came with a small, stock battery pack (2 AAA batteries) installed.  Not sure what the PN is (I'd have to open it back up) but I was surprised as all my other PS2 engines have larger packs.

That's the AAA pack that GGG mentioned.  I picked up a few of them on my last order, they are easier to fit into many installations.

I was considering this Varta 2.4 volt, 200mAh:

http://www.dhgate.com/product/...75543507.html#s3-3-1|1972515394

(Watch me catch the devil for the link format.)

Curious that you should mention the NW2, Bob D.  I'm converting a SW1500 (which I asume is virtually the same) from 5-volt to 3-volt, and find it quite cramped.  It used a 1.75"/45mm speaker, with a very flat magnet (speaker depth is under 10mm)hanging in the compartment between the trucks, and with a 3-volt board, there is no real space for even a AAA. 

Anyone know what the mfd rating is on a BCR?

The battery on bottom was in the last MTH Up-grade kit I received.

Thanks PRRronbh.  I make that as about 27mm long vice the 50mm for a regular AA.  That would certainly work in an upgrade I'm doing on a LIonel #624.  ANyone know if these are regularly available?

The top battery in the photo is the one I have in the NW2, it sits at an angle so it'll fit in the tight space.  I haven't gotten any of the smaller battery packs in any of the upgrade kits.

I recently added a crew to the NW2, also a tight fit but it was quite easy.  I made a floor for the cab using a piece of 1/8" styrene, with a horseshoe-shaped cutout for the motor.  I added 2 strips of 3/16" "H" beam underneath the sides so that it fit flush with the bottom of the cab.  It's a press fit so I didn't glue it inside the cab and used to standing crewmen from a Bachmann set of RR workers I believe.

The roll-your-own version uses a 1.5 Farad 5V cap - I'd think the manufactured version would be in the same ballpark.  Yes, when you do the math the stored energy in the 700mA-Hr pack is over 100 times greater than the BCR.  So even a 200mA-Hr pack has the storage capacity.  The problem as I see it is the discharge rate when track-power is removed during shutdown or conventional direction change.  The internal battery resistance effects a voltage drop proportional to the current being delivered.  This current is fairly high relative to the C rating (200mA, 700mA, etc) of the battery.  There was a thread with some number a while back but I dont' recall the specific.  Anyway, what is not known and unlikely to be provided by MTH are the specs on how much discharge current is required and the allowed battery drop below 2.4V.   Then you can design a solution rather than experimenting; I believe the BCR in the PS2-3V version charges to near 5V (rather than 2.4V).  So, for example, one could imagine a scenario where you could use a 3.6V pack if the size characteristics are suitable to better handle the voltage drop during discharge.

But, since the 2/3AA fits, problem solved!

I've used a number of my home-made 3V BCR clones, so far they've worked fine.  I haven't run across any issue of running out of energy before shutdown.

Stan, are you sure 1.5 Farad?  Mouser's prices for caps of that size are over $200.

You just have to know how to shop.

1.5F 5.5V SuperCap

Thanks, John.  What other components would be needed to use this to replace a battery? 

What do they use in PS3 in lieu of a battery?

Just the connector, it's a matched set of capacitors so you don't need the Zener diodes that we usually use with two or more supercaps.  Here's a snap of a completed one compared to two AA batteries, which is the size of the stock PS/2 3V battery pack.

THe batteries shown by PRR are not in the switcher, those are AA.  The 2/3 AA at 700mh are a nice alternative to some smaller diesel like the RS-3 that has a narrow and short body.  The switchers tend to have less space and the AAA is used.  Which is narrower and shorter.

The issue with a 200mah is battery drainage when not in use.  You may find you have to charge more often a sitting engine, were as the AA 700 I have can sit for months and still execute a shutdown sequence.

BCRs work the best from a space perspective because they eliminate the charge port and can fit in places the batteries can't.   G

What are the 200mah batteries?  The AAA batteries from MTH still claim to be 700mah.

Here's a contrast of the three sizes, AA, AAA, and a BCR clone.  While the BCR clone doesn't have near the energy, it's worked fine in a number of PS/2 locomotives and I have no shutdown issues.

GRJ:  Why would you bother rolling your own if you can but this cap so cheaply and only need to add a connector?

"rolling your own" involves putting the connector on the cab, see above picture!  What did you think I was doing?

Making them from scratch.

Capacitor instead of battery.

I guess I introduced this arbitrary number.  It was to illustrate the point that 700maH is way more than energy than needed for most applications given that a capacitor with less than 1% of that stored energy can do the job.  So this applies to the original post about smaller capacity batteries though I think using a 3.6V pack would be wiser to deal with G's point about voltage drop on the shelf.  The capacitor charges to somewhere near 5V which is the basis of my un-tested proposition that a higher voltage pack would be a better choice if using a 100maHr (or whatever) sized pack. 

I think he is keying off your earlier comment that the cap was constructed (by the vendor) with 2 separate matched caps.  Your photo looks like a Nesscap brand and you can roll-your-own 5V 1.5-Farad cap by stacking two 2.7V 3-Farad caps.  Yes, you have the debated issue about cap matching and the need for zener diodes (covered in earlier roll-your-own-BCR threads), but as this photo shows making it "from scratch" can provide additional flexibility in orientation, say, making a long cylindrical cap about the length of a AAA but a bit narrower if that's the only available space in a smaller engine.

Stan2004:  I was unclear in my question.  I meant what size/type capacitor do they use in PS3.

I have ordered a pair of the Varta 200 mAh battery packs and will see how they work out.  Killed me to order from China a pair of German-made batteries.

I think I'll stick with my simple to construct one, it's 1.5F at 5 volts and very simple to construct.  It's hard to imagine a place where a full sized AA battery will fit that this one won't.

I agree, but I'll try the Varta battery because I'm not ready to jump to capacitors.  MTH has indicated that the 200mAh size should be adequate.

Yes, I was thinking back to my recollection of GRJ's earlier comments on roll-your-own BCRs.

GRJ: Are you going to York?

John,

What's available to replace the 8.4 volt battery?

Are these suitable for 5V or 3V PS/2 ?  Or both?

Trevise, given that the voltage applied to the battery on a 5-volt system is greater than 8.4 volts, and that these capacitors have a 5-volt rating, I would say they are not suitable to replace a system (the so-called 5-volt system) that uses the 8.4 volt battery.  I shall leave it to the electronics experts to indicate whether there is a way to wire them up, in series or otherwise, to make them usable.

RJR said he was looking at the 200mah AAA.  It is the capacity of the battery. 

The 8.4V only have a 150-180mah rating but that is at 8.4V, my opinion is a 700mah rating is better than 200mah for the 2.4V.  But looks like RJR bought some already.   G

Make sense.

I'm sure there's an equivalent capacitor set to replace an 8.4 volt.    

Barry, You can put 2 in series. That will double the voltage but half the capacity.  G

George,

Thanks!

They are the same, though they use 2 individual ones vice the double pack version.  The double is just 2 2.5V or 2.7V capacitors in series.  G

GGG, yes I ordered a pair to see how they work.  I agree that 8.4 v 200 mAh is more power than 2.4 200 mAh.  But I also wonder what the mAh rating (if any) would be on a 1.5F cap????

I do think the standard pair of AA MiMH's may be overkill, although it does provide a reserve for extended non-use of trains.

GRJ:  How long do the 1.5F caps keep the sound on when power is shut?

Depending on the engine just long enough to complete the shutdown.  Not much reserve beyond that.

I have use the 2.5F but they are more expensive and take a little longer to charge.   G

See my previous post to Barry with the complete construction details in it.

John,

I had those instructions, however, I thought that there might be a device I could buy that was already assembled, alike the 3 volt battery replacement.

GRJ, you give me pause when you say you hook black to +.  My experience when using electrolytics was the opposite, that the + side is positive whether furnishing current or receiving it.

Is that how you've done it on the 3rd single cap example also?

Barry, there's always the genuine BCR for $24.99.

RJR, remember that we're doing this backwards, the male and female contacts on the connector are reversed from what a real battery has.  We are trying to be a battery, not draw energy from a battery.

Trust me, the + goes to the correct place.  Yes, the + terminal on the caps does indeed go to the + side of the circuit.

Understand.  The connector is set up for load, not line.