What will Cruise Commander Lite run?

Hi Pete,

 

     Many, many thanks for your info and posting those photos!!!!!!!

 

Merry Christmas, Everyone!

 

Take care, Joe.

Without the proper tools, taking the gears off is an exercise in futility.

 

I don't see my running the CC-Lite in the K-Line set as experiment, I fully intended them to be fully operational.  Truthfully, I don't expect any more issues now that I have included the 40 cent part as part of the installation.  I've replaced a number of those small motors, they don't have a very high MTBF.

 

I managed to put all the electronics and the speaker in the Hogwarts tender, it's a pretty small tender.  There was even room for 10 oz of automotive wheel weights to give the tender some stability.  The set has run for hours at home and at the club, no issues at all.  The small size of the new RailSounds boards really makes it easier, they tuck in almost anywhere.  I used a fairly flat speaker, but it offered plenty of volume.

 

Pete is correct. A two motor loco, especially with RS-385 sized motors is a job for the Cruise Commander.  Not a Cruise Lite, stall currents will quickly burn the Cruise Lite in this sort of application.  A PTC is not a fix - but an experiment, and the back-EMF servo sensor won't operate as designed with a PTC in series with a motor lead.  

 

Putting the PTC in series with 3rd rail power lead is the best way, adjusted for size based on the loads.  Or my best suggestion as designer off the boards, use the right board for the application and all will work well.

 

Jon,

 

I apologize if this sounds like a dumb question, but why would a two motor engine automatically be a candidate for a cruise commander and not a cruise commander lite?  Wouldn't the criteria be the amperage draw of the engine and not the number or motors?

 

I have a few conventional Atlas GP15's that I'm thinking about updating.  A single dual motor engine pulling 10 cars, at 18 volts, draws about 2 amps.  With the cruise lite having a 4 amp rating, this seems like an economical way of getting into TMCC.

 

Jim

Jim. Good question. I oversimplified the reply I tendered, based on that 2 motors will pull more current.  In cases where you have 2 small motors, probably a cruise lite will be fine.

 

The real concern is stall currents. If one motor draws 2 Amps, and two motors draw 4 amps then a stall will cause the cruise lite to burn up.  While stall currents are typically unknown, the best rule of thumb is a one motor loco, with a smaller motor. This is the intended application of the Cruise lite.  For example, a steam loco with one Pitman motor will stall north of 10 amps. Certain doom for a cruise lite, although if not stalled will probably work.   This board works best in Hogwarts, Polar express, starter set diesels, etc.

 

Because at stall or heavy load the amperage will be higher than your average amps.

 

Also 2A ac at 18VAC can have a much different DC amperage to the motor especially if at a lower DC Voltage.  Power is conserved  So 2A x 18VAC is 36W (roughly) and if the motor is only gived 12VDC but needs that 36W, than 36 divided by 12V is 3A DC and you are closer to the board limit.   G

For Mabuchi motors, the stall currents are listed on their website. If you don't have that data simply measure the resistance across the motor leads (while its disconnected from the motor driver board) and divide that number into the applied voltage. eg. If the resistance is 10 ohms and the voltage is 20 volts then the stall current will be 2 amps. In normal running the current is less due to the counter EMF being generated by the motor which bucks the applied voltage.

 

Pete

I will freely admit that the PTC is an "experiment", but I don't see why it's not possible that it's going to be effective.

 

Jon, can you explain why the PTC at .25 to .50 ohms would prevent sensing the back-EMF?  I'm not sure I understand why that is.

 

I certainly could be convinced that the power feed is a better location, I may give that a try as well.

 

That would be each motor Pete.  Also some of the newer motors I am seeing ohm down around 5- 6 ohms.  G

Each motor of course. 5-6 ohms sounds right for the commonly used Mabuchi as these are rated for 12 volts and stall currents are around 2.35 amps. I used round numbers just for illustration.

 

Pete

I wouldn't trust the stall currents listed.  I have seen starter set steam engine (one motor) with bad motor drawing close to 5 amps  That is the whole package, but that is much greater than the normal 1 to 1.5amps.  G

A PTC on one motor lead will unbalance the H- Bridge, and cause BEMF sampling differences. I did not state it would prevent sensing, I stated it was not designed to operate in this manner or configuration. Sensing the BEMF is timing critical, and traces on the PCB are even included in the software tuning on a Cruise Commander model PCB design.  

 

You can add the PTC, but it I will detune the operation of the system, and with the wide variety of motors that need to function, it may not be operating per design - read "optimally".  Operating unbalanced could have long term damaging results, no testing proves this is OK to implement. We have years of positive historical data without a PTC with balanced functionality. 

 

I get it that the Cruise Lite boards are on introductory pricing, so using them is desirable. However, my suggestion is to use correct model Cruise based on my rule of thumb above - otherwise you may end up with a burnt up board, and potentially a voided warranty. 

So my thinking is to use these on some starter set 0-8-0 engines, a Hogwarts engine. Yes?

I used a small Electric RR board, that is no longer available, in a Rich Yoder  GE 44 tonner that has two small motors. Significant difference in the board is lack of a heat sink.  The board fail after a lot of continual use.   I repaired it, by replacing the small round bridge rectifier that was rated at 2 amps and the (4) FET's   It does work again, but I wouldn't used it for extended use, or pull more than 2 or 3 cars.  If the lite board rating is 4 amps I'd still be uncomfortable.  EOB drives were rated for 8 amps.   IMO.
Board installed in the RY GE 44 tonner.

R2LC board installed.

Yes. The heat sinking is minimal, and light duty is a good choice. 

 

Sorry the board failed, this design is rated less than 4amps. It was for a Beep, not much more load with only a 2amp power system 

Question is:  Can the ERR light @ a 4 amp rating handle most two can motor models??? I recently purchased an Atlas bottle board out of an SW9 model where the owner had flopped it out to an ERR light.  The large SW9 horizontal motor can easily pull more amps than a two can motor set-up.

 

Another issue is related to the, soon to be, Bachman GE 44 T a very similar model to the Rich Yoder GE 44 tonner, only plastic.  There was chatter about upgrades, I assume with the ERR light board.  Will this work in the Bachman GE 44 T? 

 

After reading Jon's comments, I think I'll consider moving the PTC to the incoming power, it should still offer the protection for a stall.

 

From all the reading, and my one experience with the CC-Lite going up in smoke due to a motor stall, I'd say that I'd be careful with what I installed this in.  OTOH, for the price you can currently get them for, experimenting and "pushing the envelope" is a pretty low cost experiment.  I have a Williams A-A set that I'm going to give it a try in to see how it handles it.  I will keep my PTC and put it in the power pickup.

 

My one set of tests stalling the motor on the K-Line set leads me to believe that I'm at least getting some protection from the PTC.

 

Look at it this way.  If you cook one of these at the street price of $40 or a bit less, you still have a spare R2LC for the current going price.

John, let me add a data point here. I have a two motored Williams Trainmaster. Basically the same power that most every Williams diesel has with the two flywheeled RS385s.

When using it to pull 35 scale Milk cars it draws 2 amps according to the meters on a Z4000. Pretty efficient but that would trip your 1.65 amp PTC, no?

As you noted higher trip values might not save the board due to their slow reaction time.

PTCs might work for lightly loaded trains but I am not sure they are the right solution for anyone that wants to run long trains or up grades.

 

my $.02

Pete

Pete, I'm in 100% agreement with you there.  For anyone that wants to pull 35 scale milk cars, Jon Z. has the right advice, use the full Cruise Commander! 

 

My PTC "fix" is ONLY to protect the CC-Lite in the event of an abnormal event.  If you have a configuration that's requiring that kind of power in level operation, the CC-Lite is way undersized for the task!  None of the places I plan on using the CC-Lite are going to be called to pull anything like what you're describing. 

 

I know that Jon Z. said in his initial torture testing of the CC-Lite he was running a dual-motored diesel with 15 cars including some grades.  He did mention that it was running without a shell and thus had better cooling than inside a confined space.  As he says, that's not the intended target usage, just the platform he was using to test it.  Another note he mentioned was the diodes in the bridge rectification are probably a limiting factor, rather than the FET drivers.  They're dissipating more power under load due to the greater voltage drop across them, that makes sense.  I suspect the danger to the FETs is a sudden overload that doesn't have a chance to heat up the diodes.

 

While, as you can see from this thread, the PTC's in the motor leads are not a recommended configuration, you could try one in each motor lead, perhaps one closer to 1.0A trip current?

 

I'm also wondering if putting a PTC in each motor lead might balance the sensing and be a better configuration if I desire to protect the motor drivers as I am currently?

 

It's fun to do a little experimenting, and I'm pretty happy that the CC-Lite hit the streets, I'm planning on being a good customer.

 

 

IMO You're still pushing it.  Even if the Z 4000 meter is only showing 2 amps draw on a 4 amp design, you will still have heat build-up that has no dissipation path.  That's the purpose of the aluminum support structure/heat sink pieces, in the larger offerings. IMO  Mike CT

Mike, I agree with you on the "pushing it" for what Pete is suggesting, I wouldn't consider the CC-Lite in that environment.  My suggestions were only if he decided to give it a try.

 

I think the configuration that Jon tested it with is extreme for practical use, though it's clear what he was trying to accomplish with the testing.  Product development testing is far different than normal usage.  I used to test products to destruction for aerospace designs, that's how you know how they'll really perform.  I don't intend to use the CC-Lite in those environments, anything that's going to be pulling a large consist will get something more robust.

 

 

You guys are ,I must again say fortunate, in O you have much more space for the installation of these driver boards. We in S are very limited in space, most of the diesels we run have space only for the Mini-2. We do run some pretty long trains but its possible the trains we haul being S are lighter and also have less rolling resistance than yours. I have pulled 25 freight cars up a 1 1/2% grade and did not give it a second thought, this was with a single motored SD 9 made by Lionel in American Flyer with the Mini-2 board. The ammeter in the system showed it to draw just slightly more than 1 amp. I would love to be able to use the CC Lite but the width makes it pretty much impossible especially if I were to install sound, it gets crowded with the Min-2 in a Baldwin.

Ray

John,

 

What you are doing is valuable, once data shows the use of PTCs holds up, more uses for this type of protection will surface.  Try one in each motor lead - that is a great idea.

 

I did test the Cruise Lite, as you mentioned, a dual motored GP30 with PH-385 motors and 6% grades with plastic cars in tow.  It worked will, better than I would have expected.  Where things will go south in a hurry is a stall.  With no heat sink on the FETs the temp will quickly rise to a burn.

 

Perhaps the PTCs on the products have merit, so the code can be tuned to support the BEMF filter.  Keep us posted.

Jon, I'm going to modify my install to put one in each lead, as the unbalance you mentioned does make sense.  I'll try the CC-Lite in a slightly larger locomotive and try to accumulate some miles with some loads and see how it performs.  This will be primarily a research project, just to see if the protection affects running and also if it keeps me from cooking the board.  I stocked up on these at the great price, so I can afford to risk one or two testing the limits.

 

I don't pretend to understand all that went into the design, I'm just trying to come up with solutions to issues I know can exist.  The quick frying of the drivers in the K-Line convinced me that some kind of protection made sense, the PTC was the first thing that came to mind.  While the K-Line has two motors, they're fairly small, and is only a two-car consist, and that's all it'll ever be.  My track current readings with just this unit running around never reached one amp, usually in the .7-.8 range at higher speeds.

 

I'm not really disappointed that I had a failure, that's how you learn.  I've cooked lots of components and boards throughout my working career, some on purpose, some not so planned. 

 

Jon, I have one question.

 

A mention was made that measuring one amp at track voltage could translate into more current at the motors.  I'm not sure how this could actually happen, is this true or not true?  It would seem to me that when the smoke all settles, if I only have one amp of AC coming in that the motor drivers couldn't really see more than one amp steady state.  I can see where instantaneous spikes could be more, but not steady-state.  The FET's are regulating the current up to the maximum available, right?  Am I missing something?

If the current into the board is 1amp, then any load could not see more than 1amp, to the best of my knowledge. 

Thanks for the confirmation Jon, I couldn't see how it could based on the apparent design, just figured I might be missing something really basic. here.

 

I'm guessing the PTC in the pickups could be as effective as in the motor leads, but I'll try it both ways.

 

 

For me, this has been a very interesting and educational thread.

 

Very basic question, What is meant by engine stall?  Does this happen when one roller is not getting current?

 

Jim

Stall current is what the motor draws when it is not turning. It is a function of its internal resistance and the applied voltage. It is the highest current that the motor will draw. As it starts turning it becomes a generator and develops a voltage opposite to the applied voltage but always a lower value. That reduces the current.

Stall current flows when the voltage is first applied and also when something is preventing  it from turning like debris stuck in the gears. 

You may have observed the effect of stall current when a large motor starts up and the lights dim. 

 

Pete

Thanks Pete, that's why I see a small spike on the amp meter on my transformer when I first start the engine.

 

Jim

Normally at start up it is not called stall current, but similar principle.  It is startup current.

 

Funny, when you look at the tech documents, your suppose to size the H bridge to handle stall current plus a safety margin. 

 

This gets to Jon Z point, use the mini on the right engine with smaller motor, and even if it stalls the board doesn't get damaged.  You can use it on larger motors that normally operate under the H bridge rating, but if it stalls you suffer the consequences.  G

The small spike at startup will also not typically be long enough to cause the issue we're discussing, the overload has to exist for enough time to overheat the FET drivers.  From actual observation, that seems to be in the 5-10 second range.

 

Thanks to all for these posts, especially Boxcar Bill, gunrunnerjohn, and santafefan. I installed two of these over the weekend and the locos run great. Brought life back into some trains that were retired for not being command. One of them is a dual motor that I put the PTC into. No problems yet. Just pulls 5 or 6 cars max and one small grade. Great runners now. Thanks again.

I'd seriously consider the PTC I mentioned in the power leads, it might save the board in the event of a motor stall.

 

One thing I'm considering if I put these into something a bit larger (not real big, just dual motored), is perhaps some thermal epoxy and a heatsink on the FET's to give it a bit more capacity for brief overloads.  I'm still sticking with the PTC's, as I like to have a safety net.

 

I did note that Lionel uses the Mini-Commander 2 board in the original Amtrak AEM-7, it's a smaller dual-motored locomotive.  I was actually quite surprised to find that in there when one came in for repair. The MC2 has similar FET drive with no heatsinks.

 

It is significant to note that the two that I've fixed both needed a new board.  As the stock board isn't available on the Lionel site, they both got a Mini-Commander 2, didn't seem to affect their operation any, all the stuff still worked as before.

 

I think you mean Lionel's HHP-8, right? I don't think they did an AEM-7. I'd take one if they do!

 

I think I'll be putting a cruise light into my HHP-8 eventually. I really like this little board. I thought about the heatsink too, but I'm rolling with the PTC experiment for now.

So I guess it would be safe to put a lite board in a diesel, say traditional RS-3 that has 2 can motors in the trucks, and the output trigger for the electronic horn board?

Sorry, of course I did mean the HHP-8!  I've had two of them with identical failures, you'd think I could get the nomenclature correct!

 

Chuck, "safe" is in the eyes of the beholder.   I ran my K-Line Interurban set around with half a dozen boxcars behind the two cars for half an hour, they didn't miss a beat.  I have the PTC in-line with the motor, but the train never stopped or hesitated, so clearly I didn't make it to the cutoff point.

 

I'll want to have more experience with more variety before I declare the PTC an adequate safety net for motor stalls, but so far it looks promising.