# Amperage



## Mike Flea (Apr 8, 2014)

What is the difference between Amps and Voltamps?


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## Semper Vaporo (Jan 2, 2008)

Amps is "quantity", Volts is "Force"


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## Greg Elmassian (Jan 3, 2008)

OK, you need to understand Volts and Amps first.

Volts is like water pressure, the force of the electrons. 

Amps is like gallons per minute, the number of electrons.

In our trains, in motors, the higher the voltage the faster a motor will spin

The more amps the motor draws, the more load it can handle.

Normally in our scale, we need to know the amperage the system can supply, regardless of the voltage (speed).

So most better quality systems are rated like 0-24 volts, and 10 amps.

But, like many other things in advertising, there are ways to make things look better than they are, and VoltAmps or VA is commonly used in lower quality/power systems.

VoltAmps is volts times amps, but there is a "trick", since you have variable DC, it turns out that VoltAmps can be at only ONE combination of Volts and Amps.

What happens is that in most systems rated this way, as the load (amps) increases, the power supply is UNABLE to hold the maximum voltage.

The net result to you is that normally when you need the power (amps), the voltage (speed) drops and your train does not make it up the hill.

MRC power packs are famous for this, and it was quite a learning experience trying to get a 60 VA power pack to run an LGB track cleaning loco.

So, it is NOT Watts, and is sort of a maximum power, but almost always NOT at max voltage (where we often need it).

so if you had a 48 VA supply, and it is rated to a max of 24 volts, most people think they will get 2 amps at 24 volts (volts times amps = 24 x 2 = 48 VA)... but this is almost NEVER true.

In your case even the theoretical maximum current is very low by G scale standards. Locomotives will not draw much current running on level track with no trains. Add a grade or 6-10 cars and you will see the amps go way up.

Hope this helps.

Greg


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## chuck n (Jan 2, 2008)

Greg

The mods should put your post somewhere as a sticky or in the FAQs.

Chuck


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## Greg Elmassian (Jan 3, 2008)

Thanks Chuck, it comes up so often, and I really think rating in VA borders on a dishonest practice, because it really tells you nothing. Now if they stated the voltage it is measured at, that would help.

My experience with the LGB track cleaning loco was that I needed to run it at almost 24 volts to get the cleaning wheels to spin properly. Unfortunately I could never get to that point, as I increased voltage (or attempted to), current draw increased and output voltage sagged under load.

That's when I bought the power G, which is 10 amps at any voltage. Problem solved.

Greg


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## camper415 (Jan 18, 2013)

*i think my head is gonna explode*

but it helps explain things .


Greg Elmassian said:


> OK, you need to understand Volts and Amps first.
> 
> Volts is like water pressure, the force of the electrons.
> 
> ...


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## camper415 (Jan 18, 2013)

I have the M R C control master 20 , I bought it used no box or instructions . I am running an inner and outer mainline with 1 engine on each the outer line is an Aristo FA1 pulling 6 refrigerator cars the inner has an U S A trains NW2 pulling a combo of 11 cars , 4 of them are short lgb cars . My question is am I doing any harm to the engines as in too little power for what i'm asking them to do ?


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## Treeman (Jan 6, 2008)

If you are getting them both to run at the desired speed all is good. The power supply is providing enough voltage and amperage.......if it is not over heating.


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## chuck n (Jan 2, 2008)

I believe, that if anything comes to harm it will be the power supply. Does it get hot or warm? 

If there isn't enough voltage/current, the engines will just slow down or not run, no harm no foul, but it could destroy the power supply.

Chuck


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## Michael Glavin (Jan 2, 2009)

Greg Elmassian said:


> OK, you need to understand Volts and Amps first.
> 
> Volts is like water pressure, the force of the electrons.
> 
> ...


Greg, 

VERY succulent answer to an often overlooked and misunderstood reality... This problem is EVER present in battery powered trains, most aren't even aware of same. As you know Voltage degradation under load is a fact of life, most without realizing same mitigate the issue with larger capacity batteries in search of crazy run times in an effort to minimize charge intervals, which in of itself is a BAD thing too.

Michael


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## chuck n (Jan 2, 2008)

Camper

Type " MRC control master 20" into your favorite search engine. I found 7 pages of instructions and information. It is rated at 100VA.

As Greg said, what ever 100VA means. That is a high end VA. VA is probably best at comparing power supplies. 100 should be better than 60, but that is about it.

Chuck


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## Mike Flea (Apr 8, 2014)

Greg Elmassian said:


> OK, you need to understand Volts and Amps first.
> 
> Volts is like water pressure, the force of the electrons.
> 
> ...


 Thanks, it does help.



Greg Elmassian said:


> Thanks Chuck, it comes up so often, and I really think rating in VA borders on a dishonest practice, because it really tells you nothing. Now if they stated the voltage it is measured at, that would help.
> 
> My experience with the LGB track cleaning loco was that I needed to run it at almost 24 volts to get the cleaning wheels to spin properly. Unfortunately I could never get to that point, as I increased voltage (or attempted to), current draw increased and output voltage sagged under load.
> 
> ...


 Now I feel I got took when I purchased this transformer.



Michael Glavin said:


> Greg,
> 
> VERY succulent answer to an often overlooked and misunderstood reality... This problem is EVER present in battery powered trains, most aren't even aware of same. As you know Voltage degradation under load is a fact of life, most without realizing same mitigate the issue with larger capacity batteries in search of crazy run times in an effort to minimize charge intervals, which in of itself is a BAD thing too.
> 
> Michael


 Eventually I want to RC all my engines. I currently have some Hobby grade Rc's that run on 7.2 volt Nimh packs, most of which are 3000mah, 15 - 18 min runtimes, and a 4500mah pack that gets around 20 - 25min runtimes, but that depends on the motor. The 3000's are run in slow speed rock crawlers and get around 15 - 20 min runtimes, but they are powering not only the motor, but also a high torque servo turning large diameter tires.


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## chuck n (Jan 2, 2008)

Mike

I run several engines by battery and RC. I'm using the AristoCraft Revolution for the RC control and CORDLESS REVOLUTIONS LI-ion batteries, 18.5V 5600ma. I have the battery and receiver in a trailing box car. That way I don't have the expense multiple setups. I have three standard gauge engines that share one battery car, Aristo Mallet, Aristo Mikado and a USAT Hudson. I did get a extra battery so I can easily swap them out if needed and it is easy to remove the battery for charging. I get over two hours run time. I don't know how long the run time is because I usually don't run for longer than a couple of hours.

My home layouts are track power. I have the battery and RC for layouts I'm visiting that don't have track power.

Chuck


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## Mike Flea (Apr 8, 2014)

Thanks Chuck, I'll look into those batteries, but I'm a bit leery of using them. I've read the warnings, and not sure I want to use those.


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## chuck n (Jan 2, 2008)

Mike

The 18.5 v fine for the two Aristo engines, but I'd like a little more speed (volts) for the Hudson.

Chuck


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## SD90WLMT (Feb 16, 2010)

While RC this is RC that..one cannot equate run times of RC monster toys as a guideline for determination in use in our toy trains...
I have run 4500mah ..18v. Batteries in a large heavy dismal...it runs for many hours pulling overly long trains...
What you really need here is more experience... Directly with your trains..and their running results from use...

Trying to clarify a mis-concept I'm seeing here....

Dirk


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## chuck n (Jan 2, 2008)

That is why I charge them outside of the car.

Good LI-iON packs have excellent built in protection.

Chuck


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## rdamurphy (Jan 3, 2008)

I believe you mean "succinct"...

Robert


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## Tom Parkins (Jan 2, 2008)

I have used RC batteries for years. I use two 9.6v batteries wired in series. My standard is 3000 mah or 3 amp hours. 

Two 9.6v wired in series = 19.2 volt maximum

3000mah means if it draws 3 amps it will run 1 hour, or 1.5 amps runs 2 hours. That is theoretical. 

But it is reasonably close. I get roughly 2 hours of run time if I run two diesels off of one battery. Also depends on temperature, grade, size of train, speed of train. As speed increases it also tends to draw more amps. More rolling resistance at scale 50 mph than 30 mph. Amps produce the force to run the move the train. 

BOTTOM LINE. Nimh RC batteries work just fine.


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## Greg Elmassian (Jan 3, 2008)

I'm glad I copied my post to my site, was to be informative about Amperage, Voltage, and VoltAmps.

Not battery installations, and there are no voltamps in batteries.


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## Greg Elmassian (Jan 3, 2008)

Mike, if you have more questions about volts, amps, etc. start a new thread... I was going to expand to Ohms law and explain stuff about leds, lamps, etc.

So, if you have more questions, just start another thread, I will find it.

Greg

p.s. the thread is yours guys...


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## Wizard69 (Feb 4, 2016)

camper415 said:


> I have the M R C control master 20 , I bought it used no box or instructions . I am running an inner and outer mainline with 1 engine on each the outer line is an Aristo FA1 pulling 6 refrigerator cars the inner has an U S A trains NW2 pulling a combo of 11 cars , 4 of them are short lgb cars . My question is am I doing any harm to the engines as in too little power for what i'm asking them to do ?


If the engines run at the desired speed then you apparently have the current capacity required. DC motors of the types in these trains have to be able to operate over a wide range of voltages as voltage impacts speed. 

In other words the available voltage is what sets the top speed on a DC machine. Current on the other hand impacts torque, the more torque required to accomplish something the more current that will be drawn. This is key to understanding motors current demand goes up as the load increases. 

So to damage a motor you need to increase current demand, by loading the motor down, until it exceeds the motors rating. The power supply also needs to be large enough to supply damaging currents to the motor. So how do you know if the load is too much? An ammeter is one way but you need a spec sheet to know what the motor is rated for current wise. Either that or a properly labeled motor should have a label with acceptable operating conditions listed.


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## Michael Glavin (Jan 2, 2009)

Greg Elmassian said:


> I'm glad I copied my post to my site, was to be informative about Amperage, Voltage, and VoltAmps.
> 
> Not battery installations, and there are no voltamps in batteries.



I agree, yet is not such a thing implied by specifications of batteries Greg? 

Sorry to drag this down a spur, we can start a new.

Michael


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## Greg Elmassian (Jan 3, 2008)

voltamps is normally applied to a power source, and ones that are normally transformer based, where the voltage varies quite a bit as you approach maximum load. I've seen it used on smaller power supplies to make the numbers more impressive, besides small transformers and toy train supplies, I have seen it applied to UPS'

A "raw" battery act quite differently under load, as you know.

I've never seen batteries rated that way, though there is no electrical reason you could not do that.

Greg


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## Michael Glavin (Jan 2, 2009)

Its as simple as battery capacity (AMPS) x battery voltage (VOLTS) = VA

Not arguing its ambiguous at best, yet there is parallel IMO...

I think we can agree; power supplies aka transformers can exhibit like anomalies to battery power sources with regard to providing rated voltage/current at specified or known voltage/current levels over time.

Michael


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## Greg Elmassian (Jan 3, 2008)

the issue is that it is a pretty worthless spec, because a VA rating has only to be "true" at one combination of volts and amps.

Not near as useful as current sourcing ability over a range of voltages in my opinion.

notice that everyone looks for amp hour rating on batteries, but not what the voltage drop is close to max amp hours..

Greg


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## Michael Glavin (Jan 2, 2009)

Greg Elmassian said:


> the issue is that it is a pretty worthless spec, because a VA rating has only to be "true" at one combination of volts and amps.
> 
> Not near as useful as current sourcing ability over a range of voltages in my opinion.
> 
> ...


Ahh but they should or at least could. Its not generally a problem of our trains diminutive needs so its unknown or simply overlooked... Other uses exasperate the need to know.

Again not arguing; VA specifications don't mean much IMO either, yet there is a correlation to battery spec's.

Michael


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## Greg Elmassian (Jan 3, 2008)

yeah, in batteries won't mean much because you really want to know WHEN the voltage sags unacceptably based on the run time in minutes at the desired load.

Nothing about VA helps that, since VA only specifies, again, a number that represents volts times amps at SOME ONE data point. Without knowing even the volts or amps, it's pretty worthless, and indeed that's the major reason it's pretty worthless for our trains, since the speed of the train is not simply watts consumed, but volts with sufficient amps.

Greg


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## Mike Flea (Apr 8, 2014)

Hey guys, I've been out a couple days due to work, and have just caught up on the discussion, and this is all useful information to me. I took electronics in high school, so I understand a little, and am enjoying the refresher course, so to speak, considering high school was 40 yrs ago.

Wherever this thread leads, be it voltamps, amps, volts, watts, resistance(ohms), please continue, makes it easier than searching different threads.


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## chuck n (Jan 2, 2008)

Wiz

What you say about motors is very informative, but as far as most of our engines are concerned is not applicable. Wheel slip will happen long before the motor will burn out. You may dig a divot in your track, but the motor should be fine. Friction saves the day, or more correctly, the lack of it.

When I tested the tractive effort, pulling power, of a number of engines I tethered the engine to a fishermans scale. I gradually increased the voltage until the wheels started to slip. The slip always happened at voltages significantly lower than the full power needed to pull a train around my layout.

The one time you might be able to burn out a motor is if you had too big a load for a cog engine to pull up the rack. I don't know which would give out first, the motor, the cog gear, or the rack.

That is not an experiment I wish to undertake.

The average tractive effort was about 1/3 the weight of the engine. Some were higher some were lower. It had a lot to do with how the weight of the engine was distributed on the driving wheels and any non driving supporting wheels, such as the leading and trailing trucks.


Chuck


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## Wizard69 (Feb 4, 2016)

chuck n said:


> Wiz
> 
> What you say about motors is very informative, but as far as most of our engines are concerned is not applicable. Wheel slip will happen long before the motor will burn out. You may dig a divot in your track, but the motor should be fine. Friction saves the day, or more correctly, the lack of it.


This may or may not be true for every combination of motor and engine out there. It is current through the motor that burns out the motor not so much voltage. The gear train should be robust enough, along with the motor, so that slippage occurs before motor overload but I'm not going to say that that happens every time.


> When I tested the tractive effort, pulling power, of a number of engines I tethered the engine to a fishermans scale. I gradually increased the voltage until the wheels started to slip. The slip always happened at voltages significantly lower than the full power needed to pull a train around my layout.
> 
> The one time you might be able to burn out a motor is if you had too big a load for a cog engine to pull up the rack. I don't know which would give out first, the motor, the cog gear, or the rack.
> 
> ...


I'm not really disagreeing with you here, just that bad design does happen. the point I wanted to get across though was that the power supplies current capacity won't lead to a motor burnout all on its own. Too burn out the motor you have to overload it.


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## chuck n (Jan 2, 2008)

In theory you are correct. In a properly running engine, wheel slip will occur long before a motor will burn out.

If the motor burns out you have a bigger problem.

Chuck


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## toddalin (Jan 4, 2008)

I burned out a motor on an USA NW-2 just pulling five freight cars around the layout. The area is in a "figure 8" configuration with ~2.5% grade at one area. You do this for a few hours without stop and the motors get very hot. Do it long enough and they can burn out.

BTW, I can look into that motor's can and see that the wires on some of the armature poles have burned away wheras some are still intact.

Caca occurs.


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## Wizard69 (Feb 4, 2016)

toddalin said:


> I burned out a motor on an USA NW-2 just pulling five freight cars around the layout. The area is in a "figure 8" configuration with ~2.5% grade at one area. You do this for a few hours without stop and the motors get very hot. Do it long enough and they can burn out.
> 
> BTW, I can look into that motor's can and see that the wires on some of the armature poles have burned away wheras some are still intact.
> 
> Caca occurs.


This is what I meant about poor design. That isn't a heavy load for an engine to be pulling.


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## rdamurphy (Jan 3, 2008)

Normally, wheel slip will occur. Not always. A lot depends on the weight of the locomotive, the grade, and traction. While a particular model MAY be designed to slip, I have seen a number of them that will stall under extreme loads when hitting a grade, and the motor just sits there and cooks. The old Mantua/Tyco steam locomotives with the diecast boilers are a good example. As are Bachmann K-27's with their high gearing, high weight, and low speeds. Steam locomotives will also cook their motors if something jams up in the mechanism or valve gear locking the drivers. I suppose this could also happen with diesels if something locks up.

Robert


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## Wizard69 (Feb 4, 2016)

rdamurphy said:


> Normally, wheel slip will occur. Not always. A lot depends on the weight of the locomotive, the grade, and traction. While a particular model MAY be designed to slip, I have seen a number of them that will stall under extreme loads when hitting a grade, and the motor just sits there and cooks. The old Mantua/Tyco steam locomotives with the diecast boilers are a good example. As are Bachmann K-27's with their high gearing, high weight, and low speeds. Steam locomotives will also cook their motors if something jams up in the mechanism or valve gear locking the drivers. I suppose this could also happen with diesels if something locks up.
> 
> Robert


I can see motors Getty cooked in those situations, a stalled motor draws lots of current. This makes me wonder though why these motors aren't fused? Fused or in some other way protected. It is just good practice to protect a motor for locked rotor conditions. 

Of course the minute a fuse blows somebody will just plug in one twice the size it should be, negating any thing good a roper fuse might do.


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## Greg Elmassian (Jan 3, 2008)

Aristo started putting self-resetting thermal overload protectors in their locos.

They put them in weird spots, sometimes protecting motors sometimes from shorts caused by derailments, sometimes in really stupid places where they needed to be removed.

More damage seems to come from shorts through the loco from a derailment and that's where the focus has been.

Greg


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## fyrekop (Sep 20, 2011)

Like Greg i run the LGB track cleaning loco. I have a USA Trains 10 amp power pack and that seems to work, even at 15 Volts DC showing on the multi-meter. I've run 3 small steam engines with 3 or 4 cars each and while there was some speed loss at the high end, all ran well at normal operating speeds.


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