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Shay motor current draw question

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Shay motor current draw question
Posted by Rex in Pinetop on Monday, October 4, 2010 12:14 AM

My new Bachmann 3-truck Shay is now running.  I've installed an Airwire G2 decoder and a Phoenix 2K2 sound board.  I have an 18v 3800 mah Nimh battery that hasn't lasted very long - less than a half hour per charge.  I know there are three motors drawing juice but I don't know how much juice per motor.  Does anyone know where I can find the motor specs?

Thanks,

Rex

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  • From: Sierra Vista, Arizona
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Posted by cacole on Monday, October 4, 2010 8:17 AM

Something isn't right.  I have a Bachmann Spectrum 2-truck Shay with AirWire decoder and Phoenix sound that ran for two days during an open house in August, powered by a 12 Volt Gel-Cell 5Ah battery, and the battery is showing no signs of needing to be recharged.

Did you remove or disconnect all power pickups from the track when you installed the AirWire system?  You may have short circuits in your track that are draining the battery through the pickups.

 

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Posted by Rex in Pinetop on Monday, October 4, 2010 10:08 AM

I did disconnect the power pickups but I didn't remove them.  Perhaps I should go ahead and do that and while I'm at it I can replace the motor power leads with Airwire's shielded cable.

Rex

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Posted by Greg Elmassian on Monday, October 4, 2010 2:36 PM

Maybe you have a "leak" to the rails?

Greg

Visit my site: http://www.elmassian.com - lots of tips on locos, rolling stock and more.

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Posted by Rex in Pinetop on Monday, October 4, 2010 6:09 PM

Okay the wheel power pickups are removed.  The motor wiring goes through contact boards so I couldn't rewire them.  I did tie off the wiring to the pickups.  I hope that solves the problem.  I won't be able to test them until tomorrow when the battery is recharged.

Rex

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Posted by Rex in Pinetop on Tuesday, October 5, 2010 1:44 PM

The Shay ran for almost 20 minutes.  The battery went from 19.6 volts down to 15.4volts.  Yep it's dead and I'm officially stumped. 

1.  The juice can't be going back to the wheels/track because there is no path to get there.

2.  The battery is taking a full charge but I suppose it might be bad.  How would I check it's capacity?

3.  Could I have a bad motor?  All three motors are running the same direction and speed on my bench and on the layout.  How would I tell how much current each motor is drawing?

4.  The sound is playing correctly at least from what I hear.  Could it be drawing too much juice?  How would I check?

5.  I have the front and rear KED headlamps hooked up and they shine although not real bright.  They couldn't be drawing much power or they would pop plus this run I didn't turn them on.

HELP!!

Thanks,

Rex

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Posted by cacole on Wednesday, October 6, 2010 7:47 AM

What about the smoke generator -- do you have it turned on?   It can drain a battery in no time if it's on.  I never use one,

If your Shay is like the two-truck version, there's a toggle switch inside the front boiler cover to turn the smoke generator on or off, and since you didn't remove all of the Bachmann circuit boards the smoke generator may sitll be connected.

 

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Posted by Rex in Pinetop on Wednesday, October 6, 2010 10:32 AM

According to the circuit diagram the smoke generator is connected to the main board which I removed.  While doing so I labeled all the wires I cut.  The only connections to the Airwire board are the power to the board, the power out to the motors, the power out to the lights, and the signals from the DCC outputs.

I'm beginning to suspect a bad battery but it charges okay.  How do you check yours for a full charge?  Right now I'm just checking the battery voltage which reads 19.66v after charging.

Rex

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Posted by Rex in Pinetop on Thursday, October 7, 2010 10:42 AM

We found the problem.  Actually my wife found the problem.  It was the battery.  She suggested putting another battery in place of the new one and see how long it runs.  Not real easy but with some zip ties I strapped Thomas' battery on top of the Nimh one and it ran for well over an hour in my test with less than a half volt of drop.  Now I need to see about getting the battery replaced.

Rex

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  • From: North Coastal San Diego
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Posted by Greg Elmassian on Thursday, October 7, 2010 2:55 PM

It's always nice to have a load to test your batteries. I have a charger that will run a discharge cycle and give the tital time and total milliamperes of charge.

You can also experiment a bit and get an automotive bulb and measure the current it draws, and then leave it connected to a "fully charged" battery and see how long it stays lit.

A defective battery can indicated "fully charged" but have lower than rated capacity.

 

Regards, Greg

Visit my site: http://www.elmassian.com - lots of tips on locos, rolling stock and more.

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Posted by cacole on Thursday, October 7, 2010 6:25 PM

Greg Elmassian

I have a charger that will run a discharge cycle and give the tital time and total milliamperes of charge.

Depending on the type of battery you're using -- a NiCad or NiMh can use this type of charger, but a Lithium battery can be destroyed if you don't use a so-called "Smart Charger" made specifically for them.

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Posted by Rex in Pinetop on Thursday, October 7, 2010 10:11 PM

I also have a charger that will do a full discharge and tell me how many ma was in the charge.  Unfortunately it just does 4.8 and 9v packs for my model airplane receivers and transmitters.  Who makes the "Smart Charger" for 18v train packs?  Does it handle NiCad, Mimh, and Lion battery packs?

Thanks,

Rex

  • Member since
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  • From: Sierra Vista, Arizona
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Posted by cacole on Friday, October 8, 2010 7:56 AM

Rex in Pinetop

Who makes the "Smart Charger" for 18v train packs?  Does it handle NiCad, Mimh, and Lion battery packs?

Rex,

Here's a link to RLD Hobbies in Illinois.  Robbie has 18 Volt Lithium batteries and the Smart Charger for them.

http://rldhobbies.com/batteries-2.aspx 

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Posted by Greg Elmassian on Saturday, October 9, 2010 10:27 PM

The Maha 777 Plus does all the battery types and is used by many. It's easy to find by googling.

Regards, Greg

Visit my site: http://www.elmassian.com - lots of tips on locos, rolling stock and more.

 Click here for Greg's web site

 

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