Apr20

Written by:Tom Farin
4/20/2008 4:49 PM 

Step by step on construction of my first battery conversion - an Aristocraft Classic South Pacific Coast battery car.

This is my first radio control battery conversion for the North Pacific Coast RR.  It should also be the simplest as I have a whole box car to work with and I'm not going to attempt to deal with sound, constant lighting and a number of other issues in more sophisticated installs.

My target box car is an Aristocraft Classic (Delton) 1:24 scale wooden boxcar, lettered for the South Pacific Coast Railroad.  I purchased the car a number of years ago on eBay.  As I recall, the price was around $30.  I chose this car as it is well built, is appropriate to the era I'm modeling, and has a top that cooperated by popping off rather easily.  It also snaps back into place.  That means it will be easy to get at the innards for maintenance.



The primary purpose of this battery car is to power an Aristo 0-4-0 switcher that came in a starter set a few years ago.  I have five grandchilden.  I want to have trains for them to run when they come to visit.  While some scale fanatics may cringe at the thought of running a 1:29 Pennsy 0-4-0 switcher pulling a 1:24 scale boxcar on a 1:20.3 pike, I don't think the grandkids will notice.  What i'm going for here is minimal out of pocket cost so if something gets damaged, I can smile and say, that's OK kids.   

As I proceed through this install, I'm going to keep track of two costs.  The first is an estimate of what it would have cost had I started from scratch.  The second is my incremental out of pocket cost.  As far as I'm concerned if i can use a piece of equipment that has been laying around for a while, there is no out of pocket cost.  So far, Total Cost (TC) - $30, Out of Pocket (OOP) - $0.

Upgrading the Wheels

This boxcar will be carrying a fair amount of weight as it will be packing batteries and carrying a receiver board and other electronics.  So the first step was to upgrade the wheels from plastic to metal.  I bought a box of metal wheels from SanVal at least 8 years ago.  As I recall, I paid around $5 per wheel.  Four were required.  That brings my totals to, TC - $50, OOP - $0.



Installing the Receiver

I dug around my basement and found an Aristo 5471 trackside receiver I purchased used on eBay about 8 years ago.  As I recall, I paid $40.  Street price for a new 55471 is $92.  This receiver was never used or tested.  I'm not sure it will work.  I also own an Aristo 55471 receiver and a 55473 transmitter I purchased last fall.  The transmitter and receiver are on their way to Aristo for service.  I won't be able to test my 5471 until the units being serviced are returned.  For now, I'll assume the 5471 works.  If it does, I'll need to purchase another 55473 transmitter.  Street price is around $70.  Here's a photo of an Aristo 55470 package made up of a 55471 receiver and a 55473 transmitter.  Costs including the used receiver and a new transmitter are now, TC - $160, OOP - $70.

    

The 5471 trackside receiver case is too wide to lay flat in a box car.  I know, I checked.  I removed the four screws in the bottom of the case and popped out the circuit board.  As you can see, without its case, the board lays flat in the boxcar.  Clearance is less than 1/4 of an inch, so this board may not work in other box cars.



The easiest way to mount the board in the box car is to use the bottom half of the case.  In addition to being predrilled for the circuit board, it makes a great template for drilling holes in the bottom of the box car.  But it's too wide.  I headed down in the basement to my chop saw.  I trimmed the base on both sides right up against the posts that support the board.



With the excess width trimmed from the case bottom, it fits nicely on the floor of the box car.  The white cylinders are spacers I plan to place between the bottom case and the board.  Elevating the board serves two purposes.  (1) It provides additional room for any hot air coming off the bottom of the board to escape.  (2) It provides additional height should water accumulate in the bottom of the box car, reducing the possibility of electrical shorts.



I used the base as a template for drilling holes in the boxcar floor.  Then I inserted four #6 1" machine screws from the bottom running through the holes in the base.  I secured the base to the floow using four #6 nuts.  Then I dropped my spacers over the screw posts and the board over the spacers.  A lock washer and second nut, secured the circuit board.



You might ask why I installed the circuit board before I know whether it works.  It was rainy this weekend limiting outside activity.  I wanted to get started on a battery install.  Should this 5471 not work, it can be easily replaced with the 55471, once it returns from Aristo service.  All I will need to do is remove the top four nuts and lock washers, pop off this board and replace with the other.

Installing the Batteries

If you read through my post that steps through the equipment choices I have made, you know that I'm going to attempt to standardize on NiMh batteries and 14.4 volts.  I ordered my batteries from www.onlybatterypacks.com , 4 packs of 3500 mah 7.2 volt Sub C packs, two in stick packs and two in block packs.  These packs cost $31 apiece and two are required wired in series to produce 14.4 volts.



I ordered two different configurations as I wanted to experiment with different form factors on installs.  But for the boxcar install, it won't matter.  There is plenty of room for either.

At this point, the battery packs are in transit.  I'll update this topic once I've installed them in the car.  Total cost including the battery packs is now TC - $222, OOP - $132.

Wiring

The wiring for our battery car will need to include:
1.  Wiring the batteries in series to obtain 14.4 volts.
2.  Providing provision for charging the batteries without removing themm from the car.
3.  Connecting the battery power to the receiver.  There will need to be both overload protection (a fuse) and a switch in this circuit to disconnect the batteries from the receiver while being charged.  
4.  Output from the receiver to the engine providing power to the engine, (and smoke unit and lights?)

Want a wiring diagram for a battery car?  Here's an independent source.

George Schreyer's Battery Radio Control Tips - Lots of good stuff on the subject including some wiring diagrams - www.girr.org/girr/tips/tips7/battery_rc_tips.html

The general approach here is to buy all the components you need, get out your soldering iron and build your circuit.  I considered this option for a while.  But here's what I ran into.  In many cases you have the diagram, but not the parts list you will need.  I'm talking about specific parts numbers from Radio Shack and/or Mouser.  Without the parts numbers you end up doing parts searches through on-line parts catalogues, reviewing component form factors and ratings, and hopefully selecting the right part.  Then you'll pay relatively big shipping costs on relatively cheap items or get in your car and spend gas money driving to Radio Shack.  Hopefully your little mall RS mstore will have what you want in stock.

If this is the kind of stuff that floats your boat, go for it.  On the other hand, this is where many of my projects fall apart.  I don't get around to finding and ordering the parts, or I do and I end up with the wrong stuff.

There is another choice.  Order a battery installation kit for between $20 and $50 from someone like RCS.  Here are two of their battery kits, the first for general installs and the other for battery car installs.  I included a link to their instruction manuals.  They shos circuits for different kinds of installs using their kits.  What is really cool about this is they did all the parts searches, selected the right parts, assembled them into kits, and provided installation diagrams.  They also eliminated the use of a soldering iron for all but a few connectors.

www.rcs-rc.com/PDF/Accessories/Instructions/Install_kits/BIK_U3_6v2.pdf 

 - www.rcs-rc.com/PDF/Accessories/Instructions/Install_kits/BIK_TC_5_10.pdf

If you add up the cost of the components (assuming you know what to buy), this seems like a more expensive approach.  But if you place any value on your time, the decision to go with an installation kit is a 'no brainer'.  I'll probably go with the latter kit as the two rings mounted on the unit are RF chokes that reduce radio interference caused by motors and the like.

I'm in the process of ordering the battery intallation kit from RCS.  I'll update this section as I proceed with installation.

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