# Bachman 45-tonner voltage question



## scoobster28 (Sep 15, 2008)

After trying 6 times to power my LGB stainz with a trail-car battery system (eventually leading to its unfortunate demise) on 14.4v and 18v, I am in need of a working engine and turn to my Bachmann 45-tonner. I took it apart and built a new critter over over one of the trucks, and wired it up to receive power only from the trail car (same as the Stainz). I don't have the tools to measure how much voltage is optimal for one truck of the Bachmann 45-tonner. Is 14.4v enough? Do I need 18v or even 24v? I don't want to blow it up! And in case you are wondering, my control circuit is a DPDT for direction and on/off, an in-line fuse for safety, and then the battery pack.

Thanks for any help you can offer.

Ben


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## Del Tapparo (Jan 4, 2008)

Ben - If it is still possible to run your truck from track voltage, you can easily determine the voltage needed. Just run it at the speed you like and measure the track voltage. then size your battery pack accordingly. Unfortunately, you may never get the exact speed you would like. This is why I made the "Simple Critter Control". You can set the speed precisely using a potentiometer which then runs a 5 amp PWM motor driver. 

But back to the battery and switch ... 14.4V will likely be too fast. You are probably going to need somewhere around 8 volts. Again, measurements will tell you exactly what you need.


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## scoobster28 (Sep 15, 2008)

Del,
Thanks for your advice. I don't have a voltameter or I would do as you suggested. By the way, the controller I purchased from you worked well until I blew it up. I think I exceeded the maximum current though I am not sure of this. You and I talked about this a bit last year when it happened. I was hoping someone who either had a voltimeter or had done this already with the engine could tell me the proper maximum voltage.
Ben


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## Del Tapparo (Jan 4, 2008)

Posted By scoobster28 on 02 Dec 2010 09:31 AM 
Del,
Thanks for your advice. I don't have a voltameter or I would do as you suggested. By the way, the controller I purchased from you worked well until I blew it up. I think I exceeded the maximum current though I am not sure of this. You and I talked about this a bit last year when it happened. I was hoping someone who either had a voltimeter or had done this already with the engine could tell me the proper maximum voltage.
Ben

If you had a Simple Critter Control, it is subject to damage if connected to the battery supply with the wrong polarity. This is a compromise I made in the design in order to keep the package as small as possible, as well as reducing the voltage loss in the control. All of my other other controls do have reverse polarity protection. It is highly unlikely that overcurrent was the problem. All of my motor drivers will handle 5 amps continuously and much more than that for short periods.

Go buy a cheap 7.2V NiCad battery pack and see how it runs on that. It should be just about right for slow speed running.


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## scoobster28 (Sep 15, 2008)

Well, the polarity was not an issue because it worked really well for about 30-45 minutes and I took care when wiring it up. I think I just messed it up somehow. I orded a voltmeter online so I should have it in the next couple of days to try out the experiment.


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## Greg Elmassian (Jan 3, 2008)

You can buy an inexpensive digital voltmeter from Radio Shack or even better Harbor Freight. I strongly encourage you to have one... the one from Harbor Freight is about $5 and often on sale for $2... 

Greg


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## Westport (Nov 28, 2009)

Ben, I have two battery powered Bachmann 45 tonners with Aristo connectors simply connected to the motor leads inside the power board. The batteries are carried in an Accucraft gondola with two six volt lead acid rechargeable batteries. The batteries are connected together with positive to negative; the other two leads go to the swithces. The Aristo connectors are what I use for all my battery and r/c cars and LGB, Bachmann, Aristo etc engines. A 15 Amp at 125 VAC DPDT switch (the Source store -old Radio Shack- here) controls forward and reverse. Both Diesels work, purely by luck, as I barely know positive and negative, at a medium-more slow than fast- prototypical speed providing me with at least two hours of running on my layout's challenging grades. Smaller amp switches did not like the batteries and vice versa. 
I intend to order two Critter Controls for my two battery onboard engines as both of them need a speed control..In the past, I did have a British speed controler but made the fatal mistake of crossing polarities... 
Myron Claridge 
West Port and Yukon


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## scoobster28 (Sep 15, 2008)

Thanks for your input. It is helpful. Frankly, I have no idea why I have so much trouble with this as it is a simple concept to wire them up. I shudder to think how I would manage on DCC!


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## TonyWalsham (Jan 2, 2008)

Just make absolutely certain the track pick ups are disconnected.


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