Skip to main content

Replies sorted oldest to newest

@BOB WALKER posted:

I've been experimenting with keeping track power on when operating battery powered in order to keep the battery charged.

Isn't this kind of like having your house hooked to the public power grid for everything but running the central air conditioning from a gas powered generator???

You have an infinite power source at your wheels, why would you mess around with batteries at this point?

I am intending to do something sort of like this in the 2nd release of our Locomotive Controllers. I believe it to be full of potential problems as mentioned about shorting out the track power. Another is that Lithium batteries are not charged by hooking up to any voltage.

You could potentially use track power to power the motors when the track power is greater than the batteries, but there would need to be blocking diodes to prevent putting charge back into the battery.

I think there is a possibility of making a charging siding or spur that a locomotive could move into, then an onboard charger could control the charge into the battery. This is not the same as charging on the regular track using standard track power.

I’ve thought about this problem some too.

I think the goal with dead rail is to be able to just have two rails, and not worry about track cleaning or signal strength in the tracks. Conversely, I think the primary concern about battery power is running time and managing the charging of batteries between running sessions. For me, combining aspects of both systems would make for an ideal scenario. This is where a partially powered track and an onboard charging circuit would come in.

First to simplify wiring and allow for reversing loops with two rails, only sections of the layout would be electrified.  What makes the most sense to me would be sections where locomotives are parked, spurs, sidings, and mainline blocks between turnouts only.  Picking the longest or most speed restricted section of the layout would maximize charging time and reduce the number of charging on/off cycles.

With any dead rail scenario, I think it’s safe to assume that the communication is always wireless via Bluetooth or some other RF standard.  Therefore this should be independent of the charging state or section of the layout.

The charging circuit would need to first detect a current coming from the wheels and then after some appropriate time begin to charge the battery, switch the internal power circuitry to an output of the rectifier.  As soon as that circuit loses power, the system should immediately default to battery power, much like an on-line UPS system for a computer.  There would also need to be some sort of hysteresis to prevent the whole system from oscillating over dirty sections of track.  It should be opportunistic, but give up easily so that the loco doesn’t stall in the charging mode at a powered/unpowered transition.

As for handling shorts... if the chassis shorts the rails, then power will flow through the path of least resistance which will definitely NOT be the battery.  Shorting is a problem that must be dealt with in any electrical circuit, and adequate circuit protection is a must.  However lithium-ion batteries are definitely dangerous when they are shorted, so it seems to me any system that uses them should already have some protection against that.  I would argue that in this hybrid battery-track-charging scenario that nickel metal hydride would potentially be a better choice. Although its not necessarily the best in high current draw situations, the half to full amp or so that my engines draw I think it would be fine depending on pack voltage.  Alternatively, nickel cadmium could be used, which are superior in that regard, although are not well suited to intermittent charging due to memory effect.

If the "system" is isolated form the track there should be no reason not to be able to have power to the tracks while running battery power.

What I want to figure out is how or what to use to measure how long I've run an engine under battery power.  I often run an engine for 5 minutes, 10 minutes, 1hour, up to when the battery needs recharging.  I need something that will keep track of these accumulative short runs that I can easily see (clock display?) so I'll know when it's time to recharge.  Right now I simply wait until I "feel" it's time...or the engine stops!!!  The Deltang boards have a circuit that cuts off to prevent the battery from going down to 0.

Bob:

You probably already know, the challenge with LiPo batteries is they do not sag much when discharged. My 1st Release board (coming soon) has a battery monitor to alert the locomotive engineer using a "Fuel Gauge". As a protection against too deep a discharge the system switches off.

I am not in favor of trying to charge the battery when live running. I will be looking into it, but my gut feeling is that there will be too many issues. I do like the idea of a charging spur or siding. The Locomotive Controller can potentially coordinate with the power supply to activate as needed, maybe even control the charge voltage and current to compensate for the contact resistance.

Jonathan, I think that's what's also in the Deltang boards, but I'd still like to be able to "see" how many minutes/hours I have on the battery.

These 2000Mah and 2200Mah NiMh and LiPo batteries I'm using have been pretty stable and consistent over 5 years.  I thought I had a problem with one last month but it turned out to be a loose pin in the harness.  I can expect 2.5 hrs run time but I rarely keep track of how long I run a train at any given time.  I might run one for 5 minutes or run have a 2-3 hour operating session.  I could tell Alexa to start/stop a timer but it would be easier if I had a simple display in the circuitry that would hold a memory and could be reset.

Bob:

You probably already know, the challenge with LiPo batteries is they do not sag much when discharged. My 1st Release board (coming soon) has a battery monitor to alert the locomotive engineer using a "Fuel Gauge". As a protection against too deep a discharge the system switches off.

There are already LiIon batts out there with PCB protection for over charge/discharge.  I don't get the desire for folks to use RC Lipo's.  Different animal all together.  What's the upside to LiPo vs LiIon?

Also... Unless you are a noob and only have one engine.... What's the big deal if you run an engine to zero and now it takes 2 hours to charge?  Just go get another engine from the fleet.   A vast majority of us have more than one.

Have Fun!

Ron

Bob:

All I see on the Deltang website is a low voltage cutout. I do not see any feedback to the operator regarding battery charge. I am not aware of any system that does this.

That's what it is Jonathan, forgot what they called it.

I've found that when my batteries go low and the engine stops, I can turn it off, then back on and get it back to the yard where I do the charging, no big deal.  I do that so I don't have to pick the steamers up, diesels I pick up and take over to charge, they're not usually on the layout anyway.

@Ron045 posted:

There are already LiIon batts out there with PCB protection for over charge/discharge.  I don't get the desire for folks to use RC Lipo's.  Different animal all together.  What's the upside to LiPo vs LiIon?

Also... Unless you are a noob and only have one engine.... What's the big deal if you run an engine to zero and now it takes 2 hours to charge?  Just go get another engine from the fleet.   A vast majority of us have more than one.

Have Fun!

Ron

Running a Li-ion or LiPo battery to zero can ruin the battery.  Li-ion batteries use a liquid electrolyte and the polymer version uses a gel or solid. LiPo is more suitable for environments with more mechanical stress.

The underlying technology is the same.

I've found that when my batteries go low and the engine stops, I can turn it off, then back on and get it back to the yard where I do the charging, no big deal.  I do that so I don't have to pick the steamers up, diesels I pick up and take over to charge, they're not usually on the layout anyway.

That's what some fella's do with RC airplanes too.  With RC planes it's called a Battery Elimination Circuit (BEC).  But the BEC is in your receiver, not your battery.  Typically you can tell when the plane starts to get sluggish and it's time to land.  There are occasions, when the power just drops quick before you have a chance to do so.

So the idea is you cut the the throttle and glide as long as you can and then gently increase throttle as needed just to get short bursts of power.  You might get away with 2-4 short bursts before it's really dead.

Deadstick landings are fun with a big high wing trainer that just soars.  They are terrible for big scale planes that typically fall like a rock without power.

Ron

@rplst8 posted:

Running a Li-ion or LiPo battery to zero can ruin the battery.  Li-ion batteries use a liquid electrolyte and the polymer version uses a gel or solid. LiPo is more suitable for environments with more mechanical stress.

The underlying technology is the same.

Sorry if I caused confusion.  When I said, "run to zero", I really meant, "run until the PCB cuts them off"  You are correct, running a Lipo to zero will ruin the battery.  I fly RC planes with Lipo's and have first hand experience.  But my LiIon batts have PCB protection built in, so the battery will cut off at a certain voltage before they get too low.  LiIon's are ideal for trains.

@Ron045 posted:

Sorry if I caused confusion.  When I said, "run to zero", I really meant, "run until the PCB cuts them off"  You are correct, running a Lipo to zero will ruin the battery.  I fly RC planes with Lipo's and have first hand experience.  But my LiIon batts have PCB protection built in, so the battery will cut off at a certain voltage before they get too low.  LiIon's are ideal for trains.

Internal protection is not unique to Li-ion.

@rplst8 posted:

Internal protection is not unique to Li-ion.

I do not doubt that some do have that protection.  I know the ones I use for my RC planes do not.   I think we agree, no matter which chemistry you use, PCB should be built in, else you run the risk of draining them too low in a model train application.

I also know that my LiPo's need a special balance charger and should be charged in a safe bag or box.  If the model train user wants a permanent battery setup, Lipo's do not lend themselves to be very convenient to do that.

This Short of a LiIon Battery Test Video convinced me LiIon with PCB would be the ONLY battery I would put in my trains.  I like my trains and my house and would like to keep them.

Ron

When I was doing consulting work, I worked with two different companies that made lithium battery packs for aerospace use.  I got to see two different tests where the battery was shorted to simulate a system fault.  I only wish I could have kept the video clips, they were spectacular!  The batteries involved have a microprocessor with several sensors for each cell in the battery, and an additional microprocessor to manage all the individual cells.

The most spectacular was a 100 AH seven cell lithium battery for aircraft use.  The test was to short one of the seven cells to force thermal runaway.  The resultant carnage had to be contained inside the battery case with only a small gas vent to the outside to relieve pressure.  It didn't exactly work out that way.  The resulting explosion damaged the test chamber sufficiently that it took a few weeks to fix the instrumentation so it could be used again!

If you think that a little battery in your model train is dangerous, try a similar test with a wet cell lithium battery the size of a large car battery!

When I was doing consulting work, I worked with two different companies that made lithium battery packs for aerospace use.  I got to see two different tests where the battery was shorted to simulate a system fault.  I only wish I could have kept the video clips, they were spectacular!  The batteries involved have a microprocessor with several sensors for each cell in the battery, and an additional microprocessor to manage all the individual cells.

The most spectacular was a 100 AH seven cell lithium battery for aircraft use.  The test was to short one of the seven cells to force thermal runaway.  The resultant carnage had to be contained inside the battery case with only a small gas vent to the outside to relieve pressure.  It didn't exactly work out that way.  The resulting explosion damaged the test chamber sufficiently that it took a few weeks to fix the instrumentation so it could be used again!

If you think that a little battery in your model train is dangerous, try a similar test with a wet cell lithium battery the size of a large car battery!

Not something I want in my trains and preferably my house...



Take the size of those laptop batteries in that video and multiply by 20-30 times and you can imagine what the video I spoke of looked like.  Add to that the explosion was contained in a very solid and thick aluminum case with the exception of a small 1/2" vent, and it has all the ingredients to get interesting.  The aluminum case was destroyed and the explosion was very impressive.

I did my battery powered LC+ Camelback with NiMh battery packs, it actually worked out really well.

Take the size of those laptop batteries in that video and multiply by 20-30 times and you can imagine what the video I spoke of looked like.  Add to that the explosion was contained in a very solid and thick aluminum case with the exception of a small 1/2" vent, and it has all the ingredients to get interesting.  The aluminum case was destroyed and the explosion was very impressive.

I did my battery powered LC+ Camelback with NiMh battery packs, it actually worked out really well.

I've seen some of those batteries, and I can only imagine the destructive force. How would these compare to what is being using in a Tesla or hybrid car? Kind of a scary thought that you might driving a rolling bomb...

One of my concerns about the current generation of battery powered cars!  Once I witnessed something the size of a standard gasoline car battery explode so violently, I wonder what happens if the whole battery pack in an electric car goes up!   It really can't be pretty!

This is also why my recent automotive purchase was gasoline powered.

Last edited by gunrunnerjohn

One of my concerns about the current generation of battery powered cars!  Once I witnessed something the size of a standard gasoline car battery explode so violently, I wonder what happens if the whole battery pack in an electric car goes up!   It really can't be pretty!

This is also why my recent automotive purchase was gasoline powered.

Part of me wonders if in fifty years we’ll look back at lithium batteries as foolish like we do the hydrogen filled zeppelins of the early 20th century.

@MartyE posted:

This post is lacking a lot of information.  Help us out and give up the details!

What he said!

In principle, how is this different than operating your DC battery-power cell-phone or laptop when it is also plugged into an AC-powered charger?

A laptop's battery voltage of, say, 15-18V DC seems suitable for O-gauge...and the chargers are typically just DC-output bricks/wall-warts so relatively easy to provide starting from O-gauge AC track voltage.

Perhaps the OP has figured out a simple way to re-purpose a laptop's power/battery management circuit.  Or if willing to work at the component level there are dozens of battery-management IC chips that have the smarts to handle the various operating and fault conditions.

Add Reply

Post
OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
330-757-3020

www.ogaugerr.com
×
×
×
×
Link copied to your clipboard.
×
×