Supercap Question

White strip is the minus side.  Inquire with that seller as he seems to sell 5 pieces of other supercaps for not much more in shipping -  so about $2 each when you buy 5.  That's quite the attractive price for a 3V PS2 supercap.  You are wise to inquire here - there are supercaps out there which are not suitable for 3V PS2 due to excessive ESR.  If you don't know what ESR is, then quod erat demonstrandum.

s-l1600

 

Attachments

Photos (1)

Thanks, I missed that.

Not much of a deal, shipping is $3.50/ea and the caps cost $2.30.  The ones I use from Digikey are shipped in the US, and their shipping is the same for one or twenty, less than $3.   If you buy ten, they're $4.55/ea

Right.  The PS2/3V charging circuit is about 5V.  So the supercap will charge up to about 5V.  The battery "chemistry" limits the charged 2-cell battery voltage to about 2.4V.

Peeling the layer of the onion - this might make you cry.   The reason you want to charge the supercap to ~5V is because energy stored is proportional to the square of the voltage.  So the same supercap charged to ~5V has 4 times the energy vs. if only charged to 2.4V.   The PS2/3V battery circuit is smart enough to process the higher supercap voltage as well as the lower battery voltage. 

 

Well,  Actually we are cheating and allowing a greater voltage.  The Reason 2.4V battery works is because of the inductor or boost that adds another 2.5V.  So between battery and circuitry you get 5V for the processor when the AC power goes off.  But correct the battery port is charged at 5VDC, the output of the 5V regulator which stops producing voltage when the track AC goes off.  The battery and inductor, or supercap when used supplement during shutdown and or direction changes in conventional.  G

 

MTH Authorized Service Center

Authorized ERR Dealer

Lionel Independent Repair Tech

Virginia Train Collectors Member

GGG posted:

Well,  Actually we are cheating and allowing a greater voltage.  The Reason 2.4V battery works is because of the inductor or boost that adds another 2.5V.  So between battery and circuitry you get 5V for the processor when the AC power goes off.  But correct the battery port is charged at 5VDC, the output of the 5V regulator which stops producing voltage when the track AC goes off.  The battery and inductor, or supercap when used supplement during shutdown and or direction changes in conventional.  G

 

G,

After much deliberation I've decided to not take the BCR route.  I've ordered a couple of AAA battery holders and will insert my Enloops.

What, exactly, will happen if, by some remote chance, I power up a PS1 or PS2 engine with a dead battery? 

Thanks - Ponz

With regard to PS2, I am told that a failed white 8.4 volt battery will damage the board. I have no comment on PS1.

I have found that if one starts up a PS2 engine and immediately ups the speed from 0 and then the power cuts (as from a breaker opening), AND either the battery is dead or the supercap hasn't charged up, the engine ID may become garbled.  I've had it happen on several occasions (grandkids will often shut down the layout after a derailment, without fixing it.).

I've changed all my PS2 locos to 3-volt boards and supercaps (2.5F, 5.4V as illustrated by the Gunrunner).  The locos didn't get used enough to keep batteries adequately charged.  If you use the locos regularly, batteries are fine.  I've had MTH 2.4 volt packs last well over 10 years.

Older PS/1 boards can get ID locked with a bad battery, and I'm sure it's possible for the battery to damage the charging circuit under the right circumstances.

The battery would have to have failed to the point that it reflects a direct short to the charging circuit to cause any failure.  Normally they do not.  I am still getting trains for repair that have original white batterys and they do not cause board damage in my opinion.  PS-1 charging failures occur, but they are way rare from my experience.  PS-2 5V boards have all sorts of other issues that can cause failure, and I am not in the camp that say bad batteries do it.  I have seen too many with dead batteries that start up and run.  PS-2 3V is almost never an issue, the board self protects when battery is bad or low.  Though charging circuit failures occur when other board failure cause issues.  Like after a derailment, or operator pinching wires.  G

MTH Authorized Service Center

Authorized ERR Dealer

Lionel Independent Repair Tech

Virginia Train Collectors Member

Add Reply

Likes (0)
The DCS Forum is sponsored by


OGR Publishing, Inc. PO Box 218, Hilliard, OH 43026 330-757-3020
www.ogaugerr.com
×
×
×
×
×