# Battery Powered GP-40



## Paul Norton (Jan 8, 2008)

I finished converting my GP-40 to on-board, battery power and radio control.

A lithium-ion battery pack replaced one of the weights in the fuel tank.










A double-pole double-throw switch and charging plug replaced the smoke unit.

 

I took Greg’s suggestion and used a toggle switch instead of a slide switch. I didn’t think it would fit but it does. The switch toggles the battery pack between its charging plug and the 2.4 GHz receiver.

 As the receiver is mounted in the Plug and Play socket, it can not be wired directly to the switch. To provide the receiver with battery power, the locomotive's redundant MU plugs were unsoldered and removed. The rear MU plug was replaced with a 2-pin plug set which was soldered to the switch.

This was an easy conversion because of the Plug and Play features. No hacking of the locomotive was required, and nothing prevents it from being restored to its original condition for re-sale at a later date.

Thanks to Tom Ruby for suggesting the metal spring tabs that hold the switch cover (dynamic brake blister) to the hood be removed. Not only does it allow easier access to the battery switch and charging plug, it prevents anyone from trying to pick up the locomotive by the dynamic brake blister, and having it fall when the metal spring tabs let go.

Now if it would only stop raining so I can go out and test it on our club railway.

If you would like to view the article on this GP-40 power conversion on our club web site, just click on the link.


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## Greg Elmassian (Jan 3, 2008)

Not so fast Paul! You can't blame me for the suggestion on the toggle switch. I'm innocent I tell ya! 

Nice clean install. I do have a question, does the track battery switch allow either "side" of the battery to connect to the rails? You might consider a small drop of hot glue in the switch on top, which could be pulled off without damage later if track power was to be used. Most Aristo locos I have encountered only interrupt one side of the connection to the track. Probably no danger at all, but it could serve the additional purpose of avoiding accidental flipping of the switch to the wrong position. 

Regards, Greg


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## Dougald (Jan 2, 2008)

Paul

Install looks good ... too bad it is snowing today instead of raining like last week!

Regards ... Doug


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## Paul Norton (Jan 8, 2008)

Hi Greg!

I removed all four of the track power wires from their connector and shrink wrapped the terminals.

 










I don’t rely on the track/battery power switch when I convert to on-board battery power.


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## Greg Elmassian (Jan 3, 2008)

BINGO! 

Safe no matter what the switch is set to... but if you DO flip the track/battery switch, will it disconnect the battery? (small issue to be sure). 

Regards, Greg


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## TonyWalsham (Jan 2, 2008)

Greg, 
Most AC locos completely disconnect the track pick ups from the batteries, some don't. None are consistent in their wiring even within a particular model. 
It is partly for this reason I do not make my RCS/EVO PnP-3AC ESC's able to pick up from the track and recommend that all track pick ups be completely disable as Paul has shown above. 
I know I miss out on some sales to users who want to run a constant voltage from the track as the power source, but I never get any RCS/EVO failures resulting from miswired AC locos.


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## Truthman (Dec 13, 2008)

Can't you just check the rails with a voltmeter while battery power is applied (and the switch set to battery) to see if any battery power is leaking to the tracks?


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## eheading (Jan 5, 2008)

You could do that, measure the voltage if you are powering with voltage. On my railroad, in the garage where the "yard" is, I have a couple of reversing loops, so if my locos aren't completely isolated from the track, they IMMEDIATELY blow the fuse!! Sure lets me know quick! Better have a fast acting low current fuse protecting everything, though.

Ed


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## Paul Norton (Jan 8, 2008)

Posted By Greg Elmassian on 04/06/2009 5:03 PM
BINGO! 

Safe no matter what the switch is set to... but if you DO flip the track/battery switch, will it disconnect the battery? (small issue to be sure). 

Regards, Greg

Ordinarily the internal power buss of the diesel and its MU plugs would always be powered.

In track power mode, it would pick up power through the track power pick-ups in the motor blocks, and an MUed track powered locomotive if one was attached.

In battery power mode it should only pick up power through the MU plugs from a trailing battery/power car. The track power pick-ups should be isolated. Just to make sure, I unplug and shrink wrap all four track power wires from the motor blocks.

The switch that I installed to toggle the battery pack between its charging plug and the receiver is wired to the internal power buss in place of the rear MU cable. The MU cables were removed because they are redundant with on-board battery power.

It doesn’t matter which way I throw the A-C track/battery power switch, the internal buss is always powered as long as the switch I installed is set to battery, and not charge or center-off.

I always encourage our members to disconnect the track power wires if they are going to use a trailing battery/power car. One new member didn’t as he wanted to run his SD-45 in track power mode on his railway. One day he was already running another track powered locomotive and decided to run his SD-45 with a power car. He forgot to switch over to battery power mode and fried the locomotive’s circuit boards. As my dad was fond of saying, “No one ever listens to free advice.”


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## TonyWalsham (Jan 2, 2008)

Paul, 
I understand what you are saying about the SD-45 owner frying the loco electronics. 
The R/C maker will always get the blame for forgetfulness by the owner. So that is why I *ALWAYS* isolate the track pick ups. 
I will continue to do so until AristoCraft wire their switches the same way Bachmann do. That is, the on board electronics are either track *OR* battery power with no possibility of both. 
It would be very helpful if someone would publish an article for each AC loco describing how to cut tracks on the AC switch assembly pcb to achieve positive separation.


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## Paul Norton (Jan 8, 2008)

That would be difficult, as Aristo-Craft locomotives are constantly being updated. The boards in my RS-3, FA-1 and GP-40 are not at all alike.

I don’t know about their steam engines, but all the motor block wiring on Aristo-Craft Plug and Play diesels appear about the same. The only guess work is which of the four wires from the motor block are the track power wires that I have to disconnect? I always unplug all four and test to find out which are the only two that move the motors by applying power. I plug those back in and shrink wrap the others.

All the USA Trains diesels I have opened so far have track power wires that unplug. They are usually attached to the power distribution board as PICK1 and PICK2. The also have four wires in the connectors attached to the motor block. Two come from the axle wipers inside the block, the other two from the side frames. 

The only danger that I have heard of with USA Trains blocks, is that they may short across a return loop if the wipers across the axles inside the block and the wires across the side frames are left on. I can only guess that at some point the two axles of a motor block are under opposing polarity.


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