G-Scale - Donner's Pass   to   Tehachapi

Southern-Pacific


Dual Battery wiring Diagram used on MGRR Locomotives


Dual Battery Installation into a USA SD-70MAC

 
The following photos depict modifications to a stock USA locomotive, installing a removable top portion with an A B battery switch (center position off),  a separate On-Off switch for the CVP Decoder Board and Phoenix Sound Board, two charging plugs allowing for simultaneous charging of both batteries with two chargers, and a USB port plug for access to the Phoenix Sound Board from a laptop computer.  Plans are to have overhead coiling charging cords in the locomotive storage shed to pull down and plug into the top of the locos between runs.  The stock smoke portion of the top shell is removable by un-screwing from the bottom side of the loco shell.  I then cut it into two pieces with a razor saw.  The two smaller top shells just rest in place with gravity into the holes which are part of the USA lower shell.
 
The removable top allows for direct access to the CVP board to change frequencies with a long screwdriver.  The stock CVP board switches are left in their on positions, because of the On-Off Switch mentioned in the paragraph above.  The stock CVP board charging plug is left un-used.
 
The main locomotive top shell is left loose and can be lifted off for complete interior access.  This required an aluminum channel to be installed in the floor of the locomotive to act as a strong-back to span the floor between wheel sets.  This modification eliminates the removal of about 10 small screws tucked in around the wheel sets for interior access.
 
All circuit boards are floating on a build up of 3M foam double sticky tape.  The batteries have double stick Velcro for easy change out when needed.  The stock USA lead weight over the rear truck at the batteries has been removed.   The dual battery weight adds noticeable tractive effect on long grades.