Rolling-stock lighting - Track Charged Rechargeable Battery

[curtis]

Hi all,

I recently introduced my Father-in-Law to G-Scale. One of the items he purchased to get him started was a USA Trains Caboose. One of the things he noticed while giving a thorough read of the manual was the Caboose can be installed with a 9v rechargeable battery. This keeps the sidelights lit when the caboose is in a siding. (Page 5 for those of you interested)

I thought this was a neat little feature and was pondering doing something similar for coach/wagon lighting. In my head would be a run of LEDs to light the coaches attached to the 9v rechargeable battery and a switch (easy). However, this circuit would also be fed from track-pickups (as with the green post van or seen in this thread by John). This is where I suspect additional complexity comes in...

Has anyone tinkered with a similar idea? I suppose the closest thing I've come across is a keep-alive/stay-alive but it seems that application is slightly different.

I know the 'easy' solution is DCC as the track always has power but for the next few years I'll still be running analogue and this seemed like a fun little project.

 

[JimmyB]

So I think this is possible using a bridge rectifier in the curcuit to ensure the polarity to the battery remains the same way around, I am sure one of the "electronic whizzes" will explain with a diagram.

 

[PhilP]

If using LED's, then yes, you will need the correct polarity..

As I read the USA Trains manual:
The marker lights are either track, OR battery, powered. It makes no mention of the battery being charged in-situ. in the caboose.
In fact it states, it must be charged externally.

It is perfectly possible to do this, but almost not worth the effort (and cost). - A 9v battery will drive a few LED's for a very long time. As long as you remember to switch the lights off, I doubt you would need to charge the battery more than twice a year?
This would, of course, depend on how much running you do, and whether you run lights all day.

Given the cost of fitting a charging circuit, battery, etc. I would suggest a decent-sized Power-Buffer as an alternative?
Less complex. No problem of over-discharging a battery (if accidentally left on). Can be sized to drive LED's for ten's of minutes, if you wish?

PhilP.

 

[curtis]

JimmyB - you're right. That slipped my mind.

PhilP - that's a really good point. I think I got carried away with the solution and thanks for the correction on the caboose. The guy in the store insisted it has to be rechargeable so I incorrectly assumed it did charge from the track. I wonder why that requirement is there..

After thinking about your proposal I searched the forum again and found this thread about simple power buffer for coach lighting. I think this _should_ set me on my way and I'll tweak to suit my needs.

I'll keep this thread update when I make some progress.

 

[Greg Elmassian]

The subject comes up every so often, for a low current load, it can be done easily, but as Phil says, once you have the battery in place, normally it can run lights for a long time without help.

You would want a full wave bridge, driving a charging circuit and then charge a battery. The issue that comes to mind quickly is that interrupting the charger circuit often resets it and it starts over, which is bad for a fully charged battery. Having the track voltage power a DC to DC inverter that is set to "charge" a supercap would work more easily, it cannot be overcharged.

For a loco, many people have wanted to charge an on-board battery to extend the run time. This never works well, due to the charger resetting issue mentioned above.

Greg

 

[beavercreek]

I used large caps to do the same for coach/ loco/ wagon led strips (or single leds) ...but there is a short gap before the lights initially come on as the cap charges up (time depending on the voltage applied), but after that the lights will stay lit (depending on how many leds ...long USA/Aristocraft coaches have a lot) for a good long time BUT not as long as a battery for when left in a siding etc.
But the caps do last long enough for a station stop etc.

I used caps really to stop flickering when there are breaks in track conductivity etc., especially if going through points (eg. if the coaches/wagons do not have pick-ups on both bogies ....(even short twin bogie wagons with pickups might have a break when going through a very wide radius No6 point).

Initially I ran DC analogue and it was a simple job to hook up the caps with rectifier and regulator etc for polarity.
When I added DCC, it was just a matter of making sure that the rectifier and regulator can take highest voltage AC (use 35v components) and also the possible higher amperage.

 

[Neil Robinson]

FWIW I opted for rechargeable battery powered led coach lighting without on board charging.
LGB ball bearing pickup wheels are expensive and cheaper pickup methods tend to increase drag.
How many hours at a time do you intend to run in each after dark session? I suggest not many, giving time to recharge batteries between especially if you have a spare set and easily accessible batteries.
I use PPS batteries in these under the coaches and they come complete with on/off switch.

Battery holder for PP3 Battery with cover and switch (wire connects)

Suitable for 1 standard PP3 battery. Made from black polythene (PE)

www.componentshop.co.uk

 

[Greg Elmassian]

For me it is a matter of convenience. I designed my whole layout to minimize maintenance at every point, and have the shortest time from "I think I want to run a train" to having the trains running. That means no batteries whatsoever, locos, lights, accessories. Yes, it costs more to have good quality ball bearing pickups, but that is offset by the cost of the chargers and the limited lifetime of the batteries somewhat (not completely), but the extra $$ in is worth it to me in terms of convenience and fun factor.

Different priorities gives different decisions.

Greg

 

[Michael]

I use a battery and a switch in my coaches, sometimes the simplest solution is the best. If however someone wanted to use a battery and charge it from the track, there is no reason why it can't be done.

I've been charging my battery remote control locos for 5 years from the track, first using Ni-Mh batteries and more recently using 18650 Li-Ion ones and I haven't encountered or read about the 'switching' issues that Greg refers to. Not sure where the limited lifetime comes from either.

The popular 18650 Li-Ion battery would be ideal for this and the charger TP4056 protection circuit which costs less than £1/$1, protects the battery and switches off when it is charged.



Michael
Happy New Year to You All

 

[Greg Elmassian]

So the "switching" issue, is turning a charger on and off...

I don't know your electronic background, but if you look at the voltage and current curves on page 1 of this data sheet:

https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf

you will see that when you first start a charge, the system trys to accertain the level of charge, and knowing what I know about charging circuits, and you can infer this from the chart, it hits the battery with a bit of current and then reads the voltage. This "high current" at the beginning of a charge cycle only happens at first, and once in a normal situation, so even with a fully charged battery, it's no issue.

But the power from the track is subject to constant interruptions, and thus continually restarts the charger, and will eventually overcharge the battery, since the inital surge of charging current is done in the "blind"... so this should eventually overcharge the battery, and thus be subject to all the dangers of overcharging a lithium cell.

This is why it is not a good idea.

Also in your circuit above, you could use a boost/buck regulator to allow charging with a track voltage under 4 volts, the boost buck regulator is just a bit more than your plain buck regulator.

Hope this is clear. (if you stick to ni mh batteries, the danger of fire is pretty much eliminated, still will overcharge the batteries, but I would strongly advise against lithiums in this use)

If you are sure I am wrong and you are right, I invite detailed questions and would be happy to produce more data.

Greg

 

[Michael]

Have you actually used a TP4056? Probably not, I have one in front of me. It has charged a 18650 battery and the blue light is on indicating that it is charged and there is no current from the power supply. I can switch the power supply (aka track voltage) on and off and hey the blue light stays on indicating that the battery is not being charged. Even if it did charge for a few seconds or minutes there wouldn't be a problem because the typical charge voltage is less than the 4.2 volts recommended. This of course also extends the life of the batteries.

Please Greg stick to DCC which you are an expert at and stop detering people from switching to battery operation by giving them fake news.

Michael

 

[PhilP]

Of course, we do not know how Michael is powering his loco's?

It could be he is BPRC. In which case he would have a powered section of track (possibly in a 'depot area') where he parks loco's for charging. - A stationary engine should not suffer from power interruptions.

If he is using track-power: Then I would surmise the track would have to be reasonably clean for smooth operation of the loco's. Any decent charger should first look to 'see' if there is something connected, and what potential (voltage) it is presenting, possibly to a small load, and if the battery showed itself to be at 4.2v (say) then it should not attempt to charge the battery.

 

[Greg Elmassian]

Have you actually used a TP4056? Probably not, I have one in front of me. It has charged a 18650 battery and the blue light is on indicating that it is charged and there is no current from the power supply. I can switch the power supply (aka track voltage) on and off and hey the blue light stays on indicating that the battery is not being charged. Even if it did charge for a few seconds or minutes there wouldn't be a problem because the typical charge voltage is less than the 4.2 volts recommended. This of course also extends the life of the batteries.

Please Greg stick to DCC which you are an expert at and stop detering people from switching to battery operation by giving them fake news.

Michael

Michael, I think you need to stick to facts and read more carefully, and also avoid your personal comments. I am not deterring [note spelling) people from battery use, but warning them from potential danger from the improper use of a charging circuit.

I never said that the charger does not terminate at zero current (and by the way an LED off does not indicate zero current, but less than the on current of the LED) That comment is not germane to what I said.

I said constantly resetting the charger circuit will eventually end in overcharging since every time you apply power to the circuit it starts a charging cycle no matter what.

And I see you did not look at the data sheet, nor the current curves. I also see you do not understand how these charging circuits work.

So you should be a little more introspective and listen to someone who knows more than you do, do you indeed have a degree in electrical engineering? Have you presented any factual data contradicting my explanation of how a charger works?

No, and clearly you do not understand or appreciate that charging a lithium cell that is already fully charged is dangerous. This is a most fundamental concept on lithium batteries and if you don't know this then you are dangerous to yourself and others.

I spoke up to warn other of danger and possible damage to their trains and themselves. Since you don't believe me, go off and talk to an electronics engineer and ask him how charging circuits work. You could also do some research on this on the Internet. I would be willing to point you in the right direction.

Greg

 

[Greg Elmassian]

Of course, we do not know how Michael is powering his loco's?

It could be he is BPRC. In which case he would have a powered section of track (possibly in a 'depot area') where he parks loco's for charging. - A stationary engine should not suffer from power interruptions.

If he is using track-power: Then I would surmise the track would have to be reasonably clean for smooth operation of the loco's. Any decent charger should first look to 'see' if there is something connected, and what potential (voltage) it is presenting, possibly to a small load, and if the battery showed itself to be at 4.2v (say) then it should not attempt to charge the battery.

The issue is as I have stated, the charging circuit will normally apply a bit of charge and then read the battery voltage. No matter how clean track is, pickups are not perfect, the proof is the flickering LEDs in coaches as they roll, and the very fact we have this thread to avoid flickering LEDs, which take less current than a charger.

Yes, if you parked the cars on a track and left them there until charged AND the rest of the track was unpowered that would work well, in that particular case that does not interrupt and restart the charging cycle. I did overlook that specific case, and perhaps Michael is using that, although I would recommend a charging switch even then.

Greg

 

[dunnyrail]

Thus the Battery v Track power discussion rages again.

May I implore anyone interested in charging Batteries from track power to look for a copy of Model Railroader June 2016 where the article on P38 “Battery power without compromises” talks about a HO Loco with on board battery, DCC or Track powered, Radio Control and recharging of LiPo Batteries using Neil ‘Stanton Battery Power Supply (BPS) voltage control and charging circuit’. This conversion uses the sort of tech that many of us I am sure could only dream about, but there it is in Ho.

Now there is no mention of issues with interruptions of supply when charging as with potential dirty spots but on track power the loco can also act as a sort of Powercap equipped Loco turning the Battery backup on automatically. Or just be a Battery or with a clever turn around of a plug be DCC only. Much of the kit used must be available for our size of power requirements, sadly not easily in uk.

A fair part of the article is about converting Motor Gearbox and Chassis so jump to P40.

 

[Greg Elmassian]

It is NOT track vs battery power!!!!

It is a warning about using a simplistic charger to try to charge a battery while the train is running and getting power interruptions.

Read the Stanton site, they have a specialized charger, more sophisticated than the chip mentioned above and they use track charging by PARKING the loco or car used.

My whole point was about restarting the charging system over and over with a running train.

PLEASE, read carefully, this is all clearly stated before.

Greg

 

[Paul M]

Please guys, don't start the year with a squabble. I don't know much about charging circuits,(I should do but....) but I'm sure all advice is given in good faith. But whatever, it's clear that you have to be careful with what you do with batteries.

 

[JimmyB]

Please guys, don't start the year with a squabble. I don't know much about charging circuits,(I should do but....) but I'm sure all advice is given in good faith. But whatever, it's clear that you have to be careful with what you do with batteries.

Paul agreed charging of any battery needs to be carried out under controlled conditions.

 

[beavercreek]

What Greg says is correct about the charging issues
BUT he does, sometimes, tend to take a mightier than thou 'I know more than you do' approach, which can get up the noses of those of us who have big noses (me included).
The American forums could get feisty in the past and there were a few folk on them who did like to show off their prowess and standpoints, rather than just being pleasantly and engagingly informative.

I use DC, DCC battery and live steam.... I have preferences for either of the power sources for certain reasons:
for some reasons I use RC battery...quick set up especially with dirty track... can be left running unattended without too much concern
for some reasons I use DCC when track is nice and clean (I have brass not Stainless steel) for more control of individual locos, sounds, motor functions like back-emf etc etc
for some reasons I use DC ... some of my locos do not have DCC decoders, to facilitate visiting DC locos.. or when I just fancy simple controlled running
for some reasons I use RC Live Steam....for when I don't mind the set up time and the relatively short running period before refuelling etc or the need to keep a watch.....and also for when the track is really dirty and oxidised..

I also use battery as well as capacitor 'buffers' for coach lights, DC sound systems (like Soundtraxx Sierra) and some DCC decoders for their sound functions,
I also have used quite a lot of roller bearing pickup wheels to lessen the need of batteries or capacitors.
There are pluses and minuses for either power delivery method. Roller bearing wheels will eventually start to fail and it is expensive to replace them
Batteries need the charging circuit built and then the batteries kept in top form but will need replacing after a time.
Capacitors are pretty robust and tend to last a long time before failing but do need the charging circuit built much like battery. They take a little time to first charge up and they will only supply voltage for a shortish time when no power is running through the tracks

 

[Greg Elmassian]

My posts 5, 7 and 10 are pleasant and informative.

It only got rough when a poster took exception at my statements and posted this mightier than thou:

"Please Greg stick to DCC which you are an expert at and stop detering people from switching to battery operation by giving them fake news. "

So please place the blame on the person who could not take reason over emotion.

There is indeed a real danger, not to mention about 20 years of trying this and it not working... parking a train statically will work, but heck why not just plug in a charger and save money.

Anyway, happy new year and happy new decade.