What is more realistic when running diesels, high or low start voltage's?
What you want is a loco to start creeping along at it's start voltage and then accelerate smoothly.........what the start voltage is is unimportant. What you don't want is a loco that sits there and then "jackrabbit starts" .....0 to 100 in .5 seconds when it hits it's start voltage.
Trial and error, my friend. Trial and error.
I have a switcher that I converted from DC and I am still fighting with it a bit, but basically, the method I am using s the following:
Select a random Start voltage... say "20."
Program that number into your loco and give it a try. Does it creep along slowly? Is it jumping up fast? See where your loco Lies. Adjust/program the SV accordingly and try again.
I have one loco with a starting voltage of 20 and other with a starting voltage of 4. Each engine will be different. Trial and error.
Ah yes... I understand. Been there myself.
What DCC system are you using (or planning to use)? Basic programing is fairly easy. Just about everything is on a scale of 1-255. When you get into the more advanced stuff of configuring CV's it can really make you head swirl, at first, but then it gets easier as you go along. Pretty much every DCC system gives you the option to set a starting voltage as it goes through the program list.
If you have the time, space and equipment, why not set up a little programming track just to start fiddling with. 3-4 sections of straight track is all you really need to get started. Dive in and start programing. No better way to learn.
The voltage isn't as important as the locomotive. I am a DC operator and I can get my locomotives barely creeping at just under one volt. (I do have an amp and volt meter on my control board.) I do use a solid state GML hand throttle.
I also have a few DCC locomotives, with sound and they require a lot higher voltage to get moving. It can take as much as 6 to 7 volts to just get the sound to come on and the locomotive won't even start moving at that voltage, and by barely increasing the voltage the locomotive will finally start creeping.
Here's a video I posted a while back doing some switching moves. This locomotive is a Bachmann Also switcher with their Loc Sound system. I had a miserable time trying to keep the camera pointed at the train while trying to throw turnouts and operating the throttle without looking at it. I also hadn't cleaned the tracks for ages. There are a couple of times in the video when I dropped the voltage just below the threshold that the locomotive needed to operate and lost the sound momentarily.
Again, the voltage really isn't as important as the operating quality of the locomotive.
All locomotives start slowly or they slip, or they dump people onto their butts, or they bump into objects they shouldn't. I prefer my locomotives, whether steam or diesel, to start much like the prototype, so I use lots of momentum and inertia settings in CVs 3 and 4. CV2 is the start voltage, and it should be set at the point at which your locomotive juuuuuuuussssttt begins to turn its drivers at Speed Step 1 on your throttle. From there, any additional speed steps dialled in quickly will just provide the endpoint for the acceleration allowed via your CV3 (Inertia) input value.
So, for any locomotive, you acquire the correct address, and dial in speed step 1. Then you enter CV2 and begin to add increasing values until you see the loco begin to nudge forward. If you wish, one number higher might be better, or even two, because cold drives not used in several hours or days will not nudge forward on speed step 1 the way a warmed drive used for several minutes will. Or, if you set your cold drive to nudge at a certain input value in CV2, the warmed engine will have a bit of a jackrabbit start. This is where BEMF settings apply, and "dither", settings one cannot hope to accomplish unless one actually delves into the decoder's manual. It is worth doing, particularly in the case of the Tsunami.
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