Large Scale Central

USAT Hudson - Battery/RC

Electronics Power and Sound
#1

Hello

I’m lucky enough to have just got one of these that looks (and weighs) great. It looks to be a low-mileage early model with its Phoenix 2k2 card and manual dated 2002. Are there any other identifiers as to which version/run it is? Or even a hidden serial number?

We’re all Battery/RC and I’m looking for your experiences of converting this loco please. With previous (mainly Aristo) loco conversions I have ripped everything out and started over with all the controls in the tender. That might be very foolish with this one, where nearly everything is already built into the loco and tender. How much of the existing wiring can I retain?

Specific questions:

  • Battery voltage to haul 7 HWs at a brisk but not reckless pace up to 2.5% gradient?
  • Physical location of main switch and charge socket, assuming batteries end up in the tender
  • If USAT don’t provide a wiring diagram, does anyone have pin-outs for the six-pin connector cable - please?

Thanks in advance

Mike in UK

#2

Realize it’s amp-hours for runtime, voltage is speed. But realize this loco does not go real fast. I have one on DCC and 24v on the rails and it goes about 60 smph as I remember. Brisk is pretty much top speed.

There is a thread 2 years ago on GScaleCentral.com with the same question: https://www.gscalecentral.net/threads/usa-trains-hudson-electrical-drgs-smoker-voltages-please.309390/

Here’s the same question in 2012: http://forums.mylargescale.com/29-beginner-s-forum/21861-usa-trains-hudson-disassembly.html

Answer is same each, no schematic.

If I ever check out the pinout on the connector I will let you know.

I would advise checking the voltage vs scale speed to set the battery voltage, and then cram in all the batteries you can (more amperage, not voltage), it’s one heavy loco.

Greg

#3

Thanks Greg

Yes I had seen both of those threads and do know that amperage does not determine speed. And yes its heavy.

Mike

#4

Yes, you asked:

“Battery voltage to haul 7 HWs at a brisk but not reckless pace up to 2.5% gradient?”

So that is why I chimed in, because I think your bigger issue will be amp hours up that gradient and with that load. Was just trying to help.

Greg

#5

Thanks Greg that’s very helpful. 19.6v and 3500 maH OK?

For completeness I find by far the most helpful thread is Tony’s in Jan 2011 on LSC:

http://www.largescalecentral.com/forums/topic/14181

He thought 14.4v was OK.

Mike in UK

#6

If I remember correctly the tender wires are 2 for track power, 2 for marker, 2 for rear light.

#7

Thank you Dan that looks very likely.

Mike

#8

I think you will find that 14.4v may be slow for a passenger loco in smph…

From Dave Bodnar’s pictures of the tender, I concur with Dan on the wiring.

I have some other tips on my page: https://elmassian.com/index.php/large-scale-train-main-page/motive-power-mods-aamp-tips/usat-motive-power/4-6-4-hudson

Greg

#9

I would tend to agree with Greg on voltage required for the Hudson.

My customer was quite happy with the performance on 14.4 pulling a rake of coaches on a flat club layout.

I am about to supply battery R/C for the 25 electric versions of the Accucraft built Argyle NSWGR C38 class in 1:32 scale, which is due out soon.

Advice from Fosworks is that Gauge # 1 electric models from Accucraft need at least 18 volts for a fair turn of speed. Fortunately I will have enough room in the tender to experiment with 4s, 5s or even 6s Li-Ion packs.

#10

Interesting thread and good for you for doing your homework Mike !

USAT makes a very nice product.

#11

Update, if you look at the pictures on my site, you will see that the tender is huge, I would put the r/c and sound in the boiler, and fill the batteries in the tender.

I really agree with Tony, and with plenty of space, and the value of this loco, I surely would have a more than just adequate battery setup. If it was me, considering I like my locos to achieve near prototype speed (though I rarely run them top speed, passenger trains are one exception) I would go 6S and maybe about 4 to 5 amp hours.

Again, if you don’t need long runtimes, or will only run about 40 smph, you could go less, but why? By the way I do have an accurate scale speedometer. I was indeed disappointed at the top speed of my Hudson running on a track voltage of 24 volts, and the decoder drops 2 to 3 volts.

Greg

#12

Greg.

I guess the main reason why a 14.4 volt battery was satisfactory is because I wired the motor direct to the ESC. There are no voltage losses through the USA wiring.

The loco stock wiring was retained and fed from the battery via a DPDT relay the coil of which is controlled by one of the ESC lighting outputs.

#13

Here’s a thread on my conversion: https://www.largescalecentral.com/forums/topic/28006/usat-hudson-conversion

I used a 18 V battery in mine. I’m running an AirWire CONVRTR with a ZIMO Decoder (because of their smoke machine driver) and a Phoenix P8.

#14

Thank you all very much this is all very helpful.

Tony, I like your solution. Can you please expand on your second paragraph/third sentence - preferably by a wiring diagram showing the ESC light trigger and DPDT polarity switching relays?

And in particular where can I get such DPDT polarity switching relays?

All the best

Mike in UK

#15

Mike a DPDT relay is wired so when energized it reverses the DC polarity, all DPDT relays can do so, and are widely available.

On the point of speed, (Tony correct me if I am wrong), the lower losses with Tony’s setup is you only lose voltage through the output transistors of the ESC, which are most likely FETs.

I believe that this is the lowest resistance solution.

Most decoders/drivers have an extra “loss” because they also need reversing “logic”, for example all DCC decoders have a full wave bridge on the input.

This is also why many battery people prefer to do as Tony suggests. The original AirWire ESC is polarity sensitive, I believe to again avoid another set of diode drops, i.e. losses to the voltage.

These “tricks” usually can save a volt or two loss between the battery and the motor, and the “last few volts” are what make up the top speed of the loco, as voltage vs. speed is nonlinear.

Greg

#16

Hello Mike.

I have been making a relay pcb as described for years. I am just about out of them and they will be replaced shortly with an older version that will use the 5 volt supply and light switching outputs of the OMEGA-10 and also the COBRA-260 100 Watt ESC’s.

You could quite easily make one up yourself using readily available small DPDT relays. Make sure you have a suitable kickback diode across the relay coil.

Here is how I currently wire them.

# RELAY-1v3

Greg I use the relay idea as much as to simplify wiring USAT locos as to enable slightly lower traction battery voltages.

One way to save a bit of voltage and still have polarity protection is to use Schottky diodes instead of regular Silicone diodes.

Currently I am working on a new installation for a GP-38 that uses making the top hatch removable to access switches and the Rx for binding etc.

The article should be ready next week.

#17

Hello Tony and Thanks again

The wiring diagram is very helpful - as yours always are!

On the third one for USAT Trains am I right that the Yellow cable triggers the relay/polarity reversal and is connected to the Rear Light terminal on the RCS ESC as in the other diagrams? Very neat idea/design.

Sorry I don’t understand the instructions “Unplug USAT motor leads. Leave connected to USAT PCB”. Which leads are to be unplugged where? And what is left connected to the PCB?

I have a spare RCS Omega 3 v5 that I could use to control motor and sound triggers with an Rx 102. Can you please confirm that this should all work OK in the Hudson with retained USAT wiring?

Finally should I ask you to supply one of the last of the present version Relays modules now or wait for the replacement version and an updated wiring diagram. Certainty is more important than speed!

All the very best

Mike in UK

#18

Mike those diagrams are intended for the diesels. It should be obvious which plugs to remove for a diesel.

Unfortunately I can’t help you with which wires to disconnect for the Hudson.

Basically you remove the motor connections from the USAT wiring and feed the ESC motor output direct to the motor.

Then remove the track pick ups and feed the relay output out to what were the track pick up connections. In the case of the diesels all that is plug and socketed.

I think the updated # RELAY-5v will be more easily understood. You would use the 5 volt terminal on the ESC to power the coil and return via the reverse light connection.

I built one today but have not yet had the opportunity to test it. Will do so over the weekend.

#19

Thank you again Tony

That’s all making much more sense now.

Can you please confirm that the + Terminal on the end of the RCS Omega 3 v5 sound/light terminal block is a suitable 5v supply to the RELAY-5v?

I wait to hear how the testing goes. Please keep us posted.

All the best

Mike in UK

#20

The + at the end of the OMEGA-3v5 is traction battery voltage less a diode drop.

Use the 5v supply on the side for the Rx.