wrong about the amp draw? for Stan.

Your layout is looking beautiful and it's nice seeing 3 Challengers at work!

What's the track voltage set at on the Bridgewerks?

I shoot for just above 21 volts at the engines. I check with my hand held meter and the engines themselves. I believe that's the best for the MTH engines to run at easily, not run too hot, and make up for any dips around the yard. I've tried lower and higher. I like to stay at or below 24 volts max.

Okay, Reason I ask is it's about watts available. 20V on the rails with a 10 amp fuse is only 200 watts available.

24V on rails at 10 amps is 240 watts available or 20% more power at same fuse rating. 28V will give you 280 watts.

If I were you I'd try cranking up the track voltage and go back to using a 10 amp fuse...fused at 15 amps may just wipe out the TIU channel...I've done that by forgetting that I had a 20 amp fuse installed one day

 I think I may just go passive mode now that I know about adding a choke.

I don't usually go over the ten amp limit. Now that I have more engines and equipment, it may become a regular event?

I did not like the MTH engine's responses at or above 27 volts. It may have been some other event occurring? There were things going wrong a few years back and I had to establish some basic rules to follow on my own. Some user's advice did not work out on my layout. I also changed the block's wiring and was advised it should not matter, but it worked.

Yes, well-done blending of the layout into the yard and landscaping.

Some comments in no particular order.

1. I think you're referring to a conversation we had in another thread where one might "budget" 100 Watts for a G-gauge engine put to the task (heavy load, climbing grade, whatever).  I believe you're running ~22V DC.  So if blowing a 10 Amp fuse, that suggests your 3 Challengers are drawing more than 220 Watts (Power = Volts x Amps).  So that's over ~75 Watts per engine.

2. I'm positive that MTH G-gauge smoke unit can consume more Watts than an O-gauge unit.  I've opened up many smoke units for to see what I could re-purpose for non-train smoke projects.  The MTH G-gauge smokers can easily exceed 10 Watts.  You should be able to watch the Amp meter on your Bridgewerks and (especially given 3 engines) you should be able to calculate the Watts (Volts x Amps) with smoke off and on...and divide by 3 to give the average smoke Watts per Challenger.

3. Note that with DCS motor and smoke electronics, it's about POWER.  That is, if you are drawing 10 Amps at 22V you should be drawing closer to 9 Amps if you can run it a 24V.  I recall you had some issues when turning up the track voltage.  But to the extent that you can increase the track voltage, this might buy you some margin on your fuse value.

4. Also, for a given track resistance the voltage drop from the transformer to the engine is proportional to current.  So if you can run less current down the track to distant engine(s) that means less voltage loss.  Of course for winter operation I suppose you can apply the wasted heat from track resistance to melt the ice/snow off the track! 

5. If you had signaling issues when going to passive mode, I'd try the choke.  Note that the TIU has such a choke right at the Voltage-In connectors.  I believe one of the guys identified a suitable high-current choke (30 Amps or something like that) for a passive-mode configuration for operation above 10 Amps.  It may be published somewhere but there is likely some combination of TIU components that serve to limit the power you can safely run thru a TIU fixed channel.  I'd have to do some research but it could well be the choke in the TIU is not rated for 15 Amps...hence fusing a TIU channel at 15 Amps in active-mode might be a no-no.  Additionally, there are Emergency-stop relays on the fixed-in channels that carry the full current in active mode - in other words there are likely multiple internal TIU components which conspire to limit the safe operating current in active mode.  

6. And in the pie-in-the-sky category, given your thoughts about battery-operation, I was pondering the idea of some kind of hybrid G-gauge scheme where an engine is jointly powered by track and battery.  So, for example, on maple-sap infested sections of track, the battery might take over or at least assist.  The battery could be charged on-the-fly when running on clean sections of track.  Or the battery could kick-in when climbing grades...and then charge when going downhill or on flat sections.  

 Thanks Stan! (again)

I am very interested in #6 and always thought about it for the future.

I never attached a choke in passive mode so I don't know what choke(s) to purchase? Could it just be the small ones I install into lighted pass cars and engine installs? Is there a reason for the higher amp ones in passive mode? (spikes?)

Those small 5-cent 22uH inductors used for passenger car LED lighting can't handle the current levels; they are suited for applications using, say, 1/10 Amp. 

You can search yourself for 22uH inductors using terms like "power" or "high-current" and so on but here's one that should work for you:

This one is rated 16.4 Amps and about $2 at DigiKey.  I see it's out-of-stock just now but available same price at Mouser.

Choose one rated for more than your actual current requirement.  It is somewhat confusing that some listings like the one above on eBay show the Watt rating of the inductor rather than the Amp rating; that's a separate discussion or rabbit-hole.  I also think using the term "inductor" rather than "choke" might yield more hits though I didn't try the experiment.  

If you search OGR using the relevant terms I did come across some other even higher-current inductors...though some had prices pushing $10. 

I use chokes rated at 5A or higher for locomotives, and obviously for track power, you need to at least match the highest current you are capable of drawing from the power district.

gunrunnerjohn posted:

I use chokes rated at 5A or higher for locomotives, and obviously for track power, you need to at least match the highest current you are capable of drawing from the power district.

This is the part I am not understanding correctly. I was thinking in passive mode, the choke would not see the full current? In other words, I want to apply the DCS signal on top of the tracks power source without drawing the current thru the TIU. It must see it then?

 It did not take long for that larger 15 amp fuse to bite me hard. One of the Challengers was used to put some cars away up the shed track. As it was backed thru the switch, the engine derailed and bridged the whole switch. Our grandson yelled to me to kill the power as he got nervous and did not hit the E-stop.

 As I pulled down the handle I noticed the amp draw was at like 14 amps! I wondered why the fuse didn't blow? Then I remembered the increased fuse size. The funny thing is the equipment survived the current draw as far as I know. The layout did not. It appears that there's no voltage going past this switch now. So something got burned. I need to remove the switch in the morning light and see what happened to it.

 I have to guess that the engine might be OK but I'll inspect that as well. I tried a different diesel engine and the rest of that mainline was OK and ran. Just not that particular block past that switch.

 Never change what you know is correct!