Large Scale Central

Trail car as alternate battery source questions

Electronics Power and Sound
#1

I know Tony regularly sets up his R/C conversions to allow the charge jack to be used as an alternate battery input jack to extend run times. Since I’ve had my Shay go dead on me out in the garden several times I’m thinking I should set it up to allow a rescue battery.

When I installed my Run (on)/ (off) Charge switch I used a DPDT type with the batteries connected to the center. In the On direction (Run) the battery is connected to the R/C electronics. In the Off (Charge) position the battery is connected to the charge jack. Configured like this I can’t use the charge jack as an input to the R/C electronics.

I used to be good at this stuff, but I’m getting rusty. I’ve been trying to figure out the wiring diagram but just haven’t hit on it yet. Perhaps that is because the charge jacks I have do not have a reliable built in switch sensing the presence of a plug so it can’t be used as part of the circuit - if that even matters.

Anyone have a circuit diagram made up I can steal?

#2

Check out my “Battery Conversion Module” manual, available on-line, and maybe you can figure it out from that. :slight_smile:

#3

Jon, here is how to wire up a DPDT switch and 2.5 mm jack to do what you want.

http://www.rcs-rc.com/PDF/Acessories/Installation-kits/U-BIK-3.pdf

#4

From the battery powered and radio controlled Connie article on the Ottawa Valley GRS web site.

http://ovgrs.editme.com/files/Connie/DPDT02.bmp

A small circuit board holds the screw terminals for the battery pack and charger wires, self-resetting fuses, and the DPDT center-off switch.

http://ovgrs.editme.com/files/Connie/Polyfuses16.bmp

The battery pack is connected to screw terminals 1 and 4.

The charging connector to screw terminals 2 and 3.

Terminals 1 and 2, as well as, 3 and 4 are connected with jumper wires.

The red and black wires diagramed are the battery power wires to one end of the switch.

(http://ovgrs.editme.com/files/Connie/Polyfuses02.jpg)

(http://ovgrs.editme.com/files/Connie/Polyfuses04.jpg)

#5

Thanks guys. I’ll check all of those suggestions out when I get home tonight.

#6

Thanks again -

Tony gets the cupie doll as his diagram actually shows what the switches do. You need to kind of interpret the shunt switch on the coaxial jack, but if you know it is there the diagram makes electrical sense.

In my case; I remembered that my coaxial DC jack does not have the shunt and I only had room in the smoke box for a tiny SPDT - Here it is just before buttoning up…

(http://lsc.cvsry.com/Post3/CVSRy5-84.JPG)

Also, with the jack up front it doesn’t really make it easy to hook up a trail car.

SO

I’ve decided a second coax jack on the rear and another well hidden switch will allow me t select between on-board or external battery. The caveat is that I need to remember that both switches need to be properly oriented to run off the internal battery.

Perhaps a simpler method would be to simply use the shunt switch on the rear jack to interrupt the connection to the front battery.

#7

Jon - If you have to add a second connector to the trail car, I would suggest not using a coaxial jack. They aren’t really the nicest looking things when a mating plug is inserted. I would go with a little 2-pin connector of some sort.

#8

You can do it manually by using a SPDT switch to select the on board batteries or the trail car.
I make positive the common in my kits and switch the negatives.
If you are doing it manually you could switch the positives instead.

My diagram shows how to do it with automated control of selecting the on board or trail car batteries. Sure the DC plugs don’t look so good but at least they are cheap, readily available and reliable. The internal jack contacts can handle 5 amps just fine.

The only real drawback to the automatic idea is you must remember to switch the loco OFF before inserting the charger. If you leave it ON and plug in the charger it would be possible for the charger voltage to get to the ESC or sound system. Some chargers have a quite high voltage output. Especially with Ni-Cd’s.

#9

Thanks again.

I’'m really thinking more of just a rescue battery. I have several packs with Tamia plugs that I use in my full function trail cars (Battery + R/C + Sound). I also have a Tamia to Coaxial plug adapter I use for charging locos with on-board batteries. So I’m not so worried about the look so long as I can conceal the jack when it’s not being used.

I also have coaxial plugs in stock. I need to look at the shunt switch on them to see if it is on the tip or ring side of the plug. If on the ring I could use it to interrupt the on-board in favor of the rescue battery.

Tony - I also switch the negative side and I wire my coax plugs tip positive.

The reason for all this is I’m thinking of getting the Shay in shape to take to Bob’s operating session and I don’t want to risk having it die out on his layout after a long day of switching without a way to rescue it.

#10

I mount the charge jack cum aux battery port on the back of the Shay bunker in between the ladder rungs. Painted black t is unobtrusive.

http://www.rcs-rc.com/PDF/Acessories/Installation-kits/BIK-BGL.pdf

#11

I found a black one in my junk box that has no external hardware. I think I might be able to squeeze it into the sand box. My tender is about full up…

(http://lsc.cvsry.com/Post3/CVSRy5-76.JPG)