Battery powered/Radio controlled locos

[DavidLong]

Fancy starting a thread on this so we can follow your progress?

I for one would be interested to see your approach

Rgds,

Stuart

 

I'd be interested to see it too!

 

David

[fallen]

I posted this in another thread but maybe its better here. I'm still finding my way around I'm afraid.

 

Here are a couple of videos I posted a month or so ago of a 009 Peco tram loco kit on a Kato tram chassis with radio control from DelTang:

 

Here is a video of the loco running round a train on my "developing" layout (really just track so far):

 

 

and here is a closer look at the loco uncoupling:

 

 

It runs very smoothly. It's not awfully fast (the video shows it at full speed) but it's fast enough to by prototypical I think. It has really good slow speed control, like DCC, and of course it does not hesitate at points nor refuse to start without a nudge or a prod. I think this is the most impressive part, you turn the knob on the controller and it just starts off!

 

In the uncoupling video for instance it's very easy to position the train over the uncoupler (I'm using Greenwich couplings with under track magnets).

 

Frank

[Robin2]

@Frank - cool videos.

 

@StuartM, @David,

 

I've thought a bit before answering your request (which is unlike me!).

 

I have already unsuccessfully petitioned Andy to have a front-page link to radio control (to this thread and another on the 7mm group about r/c road vehicles) - because I think people will only find this thread by accident. Perhaps you could have another go at him?

 

However I'm not at all convinced that another new thread will be helpful - won't it just leave people even more confused about where to post ideas and questions. Of course I will listen to counter-arguments.

 

Having said that I will be delighted to share my modest experiences with anyone and everyone, including, if anyone wishes, the program that I've written that allows my Arduino to send PPM signals to the Deltang Tx1 transmitter.

 

At one level switching to radio control is easy-peasy. Install a battery and a switch; connect two wires from the receiver to the battery; connect two wires to the motor; switch on transmitter; switch on receiver; drive.

 

The complications are in fitting all the bits inside a small body - which is really a mechanical exercise.

 

There is also the issue of recharging the battery. It's probably not practical to remove the batteries to charge them or to swap a fully charged battery for a depleted one (as the R/C flyers would do). So I am using pickups from the track to charge the battery. My idea is just to have charging power in the fiddle yard. With 3 locos each should spend at least 2/3rds of its time there so I don't expect the battery ever to become depleted - but that's not tested yet. I have installed a small rectifier in the loco (made from 4 diodes) so that it doesn't matter which wheels contact the positive track. The rectifier also has the advantage that the battery energy can't get to the track and short-out with another loco's battery. LiPo batteries need careful charging and I have found a circuit on the internet that allows me to adjust the voltage and limit the current. The interesting bit will be when I convert my bigger locos using 2 batteries each (7.2v as compared to 3.6v for the large prairie). I am hoping I can put a dropper resistor into the Prairie so that it can charge safely from the higher voltage needed for the other locos. But that, is a week or two away.

 

As I think I said in a previous post, my plan is to be able to control my trains from my PC and, if I can get my computer-controlled-fiddle-yard-turntables working, I hope the computer will be able to run an end-to-end service without my intervention - so I can sit back and watch trains just as if I had room for a continuous loop.

 

I think that covers the key issues that I have encountered.

 

It's probably best if people ask questions.

 

...R

 

PS It's not necessary to use a computer to control the trains. If you have a suitable transmitter (like the R/C flyers or car people use) that will work fine. You can see that in the Video on the Deltang website.

Edited May 8, 2013 by Robin2

[fallen]

Robin,

 

Very nice to find another radio control enthusiast. I am sure this is a technology which has now reached the point that it can be applied even to small scale railway modelling and it offers many advantages, although it will not be for every layout especially continuous run layouts for which it will have fewer advantages and more disadvantages. Good to hear you are trying it out and I look forward to seeing the results.

 

A couple of points on your post if I may,

 

I have not found battery life a problem. The battery in the Peco loco is a single cell 180mA-hr and should theoretically run it for 2-3 hours continuous. That's a lot of shuffling in and out of a terminus or shunting in the yard. In practice I have not had it run down on me yet. Recharging time depends on the current, it will happily take 500mA and at that rate charges in ten minutes or so from flat, but I do take it out of the loco for that. At 100 mA, which I would leave it in the loco for, it would take maybe an hour or so. The loco I am currently building will have a charging socket in the cab and a lift off cab roof.

 

Charging from the track can be difficult unless you build the charging electronics into the loco which is another board to find space for. LiPos need to be tightly controlled when charging and this is difficult with track and wheel contact resistance between charger and battery. Two cell LiPos, of course, need to have balanced charge to the two cells which is another complication.

 

I use the radio control electronics from DelTang, they work really well. The receiver is tiny but controls the loco very well. I also use his transmitter which is fairly inexpensive and looks comfortingly like a wireless railway control unit as it has a switch for direction and a knob for speed.

 

Frank

[Robin2]

This is a link to the web page where I found the circuit I am using for LiPo charging http://shdesigns.dyndns.org/lionchg.html It seems from the "Charge Characteristics" graph that charging is straightforward as long as the batteries aren't severely discharged, the current is limited and the upper voltage limit is reasonable. I don't plan to leave them unattended while charging.

 

If anyone has any alternative information I would be interested.

 

...R

[StuartM]

Andy has agreed to to start a separate thread dedicated to Battery powered Radio controlled locos after the competition has ended

 

Hopefully this will become a really useful page that will ventually point the manufactures in the right direction

[Robin2]

That's good news. Hopefully he is just going to move this Thread to a more accessible location so that all the info it contains remains available.

 

...R 

Edited May 10, 2013 by Robin2

[fallen]

Hi Robin,

 

Interesting charging circuit. I can see why people say it isn't sophisticated enough, usually there is a dedicated LiPo charger IC that is used, but if it does the job and meets the spec then why not?

 

I think it would be a good idea to keep an eye on it whilst it charges though, even just at first to build up confidence.

 

I will be interested to see how you get on with it. Do you plan to build this into the loco?

 

Frank

[Robin2]

Hi Frank,

 

There is no room for it in the loco so I will use the charging circuit to feed the appropriate voltage to the charging track in my fiddle yard. I am hoping there is room in the small loco for a couple of small resistors to make a voltage divider and that a voltage divider is an appropriate way of charging a single cell from a 2-cell voltage. I haven't experimented with this yet. To stay on the safe side I don't intend to do fast charging.

 

...R

[fallen]

Hi Robin,

 

Charging through the track from a lineside charger is thought to be difficult because the voltage lost in the wheel/track contact resistance means the charger does not see the true battery voltage. Also, a voltage divider might work with a direct connection but will reslt in much slower charging I think. Overall I think this will result in slower charging which may not be a problem as the upside is that charging on the track will mean you will not run the battery down so much perhaps.

 

I think monitoring the charge will be quite important here. Do you have a meter you can monitor the voltage on the track with?

 

Frank

[Robin2]

I don't want to give the impression I have any expertise in relation to LiPo charging - quite the contrary.

 

The circuit I got from the internet regulates the voltage (I have a digital multimeter - or three). With my single cell setup I have set the voltage high enough to get 4.2v at the battery after allowing for the voltage drop (about 1.3v) across the rectifier diodes. That's measured with direct connection to the pickups. If there is a voltage drop at the track/wheel or wheel/pickup interface it will act to make things safer (and slower to charge, as you say).

 

I have measured the charging current (while sitting on the track) at about 30mA but at the moment I have no idea what state of charge was on the batteries when they were delivered. I could obviously increase the current by increasing the voltage but I am happy to play safe for now.

 

I have yet to experiment with a voltage divider. If it does not work safely I will have to have different charge tracks for the locos with different numbers of batteries - not insurmountable but it is a potential source of error.

 

I also suspect that the charging rate may be more of an issue for the locos that retain their 12v motors as I expect they will consume more power. But maybe I can fiddle with the track voltage to deal with that, and then readjust the voltage divider on the Large Prairie to take account of any changes.

 

I will probably order the receivers for my other two locos in the next few days and then more experiments can follow.

 

...R

[StuartM]

It might make sense to use a standard motor and battery in each loco if charging different types of battery becomes a problem,

although the charger I use for charging my standard rechargeable battery's, charges different battery's of different ratings,

I'm no expert, but surly a battery will only take the charge it requires and then the charger will stop charging, failure to have such a cut off would be potentially dangerous.

 

With regard to a charging track, a simple rectifier should suffice to provide fixed polarity, ie: a fixed positive rail and a fixed negative rail.

[Robin2]

Hi Stuart,

 

The problem (as I see it) is that if you standardize on a motor/battery combination you will limit the range of locos you can convert or you will bring on yourself extra work changing motors that wouldn't need to be changed if you could use batteries that suit them. This would be less of a problem in larger scales where there is more room for a "standard" battery.

 

A battery is easily overcharged if it is fed with a too high voltage. In the case of LiPos I believe fire is a likely consequence. If the battery is fed with a modest voltage the charge current will indeed reduce to a trickle as the battery's internal voltage rises to match the external voltage. But with that modest voltage the overall charge time might be too long - hence the use of complex chargers. I am currently (no pun intended) planning to charge with modest voltages.

 

I'm not sure what you have in mind with your comment about the rectifier. Perhaps are talking about rectifying the output from a mains transformer. However there is another issue - which way round is the loco placed on the track? This doesn't matter when there is no battery inside the loco. As I am planning a couple of fiddle-yard turntables my locos will have to be able to deal with being "the wrong way round" on the charging track - hence the need for a rectifier inside the loco.

 

...R

[StuartM]

"However there is another issue - which way round is the loco placed on the track?"

Good point!

 

Regarding battery sizes; when the manufactures start producing battery powered/radio controlled locos, which they will, its just a case of when. I envisage the chassis becoming the battery (see previous comments and, I'm mainly talking nguage here because that's the size I work in)

Of course in the bigger scales eg:00 battery size is not a problem as there is masses of room inside those larger models

[Fen End Pit]

I'm late into this thread, but very interested in the idea of wireless control particularly for 16mm scale Simplex locos in a sand-quarry.

 

As my systems are already DCC I'm very much in favour of the 'replace the rails with wireless' approach of creating a device which sits in the loco, connects to the wireless and a battery and then provides a DCC signal to the existing loco decoder which would be identical to what would have come from the track previously.

 

This is what the Tam valley system does. My concern with that system is that the wireless component seems a little simplistic, being designed for US basement layout use rather than a UK 'exhibition circuit' type model. My fear with this system is that there appears to be little (if anything) by way of preventing two adjancent systems from interfering with each other. I think you would need someway to ensure that the recievers and transmitter at least validate that they were a pair, even if you don't want to get into encryption etc.

 

It would seem that using some commercial standard for the wireless traffic would be advantagous, which I guess comes down to bluetooth, XBee or Wifi. I could imagine an Arduino with an XBee shield or the like making up the receiver. More than that and I'm out of my league and hoping someone with MERGish tendancies gets interested.

 

David Barham

[StuartM]

Hi David, welcome to the discussion.

The way I see it, every loco would have a unique address,

Just like a stadium full of people can all have mobile phones that only answer their number.

This would all go on under the hood.

But it would make sense manufactures to get together at the start and create a 'standard address system' for rc locos before they all launch off in different directions,

that way all controllers and locos would be compatible with each other.

[Robin2]

The Deltang radio system that I use is complete in itself and doesn't use DCC so I have no advice to offer on that front.

 

You can use the Deltang receivers to operate lights with some of the extra channels. I don't know if it's possible to control sound systems.

 

The Deltang receiver is "bound" to a transmitter so there are no interference issues.

 

...R

Edited May 14, 2013 by Robin2

[Robin2]

I've been interested in trains planes and automobiles (and boats) all my life - both full size and models. I like making things and fiddling with things. I'm not so good - or so interested - at finishing things, but I love starting. However I have never really been interested in actually driving model trains. And last night I suddenly realized why.

 

I have mentioned earlier in these pages that I have converted my Grafar Large Prairie to BPR/C but I had only run it on a 400mm piece of spare track for testing. 

 

Yesterday I decided I really should try it on my "developing" layout. And IT JUST WORKED. I could run up and down the track or go in and out of sidings without any hesitation. And when one of the loco bogies derailed it just kept going until the whole loco derailed. Just like the real thing.

 

Previously with all my track powered locos (both OO and N) I could guarantee that they would get stuck somewhere and need a push start. And that was why "playing trains" was never interesting. 

 

Hooray for BPR/C.

 

...R

[StuartM]

And no wiring involved, this is what it's all about

Nice one Robin

[StuartM]

Andy Y has given the idea it's own spot, Many thanks Andy

http://www.rmweb.co.uk/community/index.php?/forum/228-radio-control/

 

It's now up to us to try and get the manufactures to take this idea and run with it

Edited May 19, 2013 by StuartM

[raymw]

Hi,

 

A couple of Items that I wrote over a decade ago, but possibly still relevant wrt batteries (although concerned with a/v applications, the same problems are present in powering models). http://yertiz.com/rwc/lithium.htm

 

  and http://yertiz.com/rwc/batart.htm

 

wrt battery chemistry, the new kid on the block is Lithium-sulphur - a higher ptw ratio than Li-ion, and is inherently safer and will be cheaper (at least to make). The technology is still under development, but looks impressive, so far - http://www.newelectronics.co.uk/electronics-technology/lithium-sulphur-cells-set-to-change-the-battery-landscape/50314/

 

Best wishes,

 

Ray

Edited May 19, 2013 by raymw

[Robin2]

Yesterday I removed ALL the wiring from under my baseboards and ordered 2 more Deltang receivers. 

 

Soon, and for the first time in 30 years of dabbling with model railways, I will be able to "play" with my trains.

 

...R

[StuartM]

Yesterday I removed ALL the wiring from under my baseboards and ordered 2 more Deltang receivers. 

 

Soon, and for the first time in 30 years of dabbling with model railways, I will be able to "play" with my trains.

 

...R

Cool, any chance of a video as this will demonstrate to people that it really is possible

Rgds,

Stuart

[NorthHighlander]

Hi everyone..

We've just come back from a very successful ExpoEM - our first time at that show and the response from the visitors to Acc+Ess Protocab was great. We were showing 1 x O gauge 'Terrier' (on and off hauling a wagon with a half kilogram weight in it!), a Hornby Dublo 3 rail 'Duchess' hauling 4 very rusty three rail coaches, a Mainline 'Warship' hauling four Mainline BR Mk1 coaches, a Heljan 'Hymek' and 'Crompton' both converted to P4, all operated without any wiring to the track and from three independent controllers. A number of young kiddies with their parents were taking the controls!

All the locos ran for the whole day on each day with the exception of the Duchess which, with its beefy motor tended to drain the battery after around 90 minutes of constant running.

The only calamity was that a length of rail on one of the Hornby Setrack circuits had come adrift in transit to Bracknell (it's a long way from Caithness!). Apart from that nothing untoward except at least two visitors begging us to have the system available for sale! Well, our answer had to be it won't be long, but we won't release anything until fully tested and emc compatible which is our next step. We're just in the throes of finalising and testing the security routines to make sure that one loco can't be controlled from an unauthorised controller and making some design changes to the LCU Interface Unit to simplify charging and on/off switching. There are still some throughput problems to iron out but they won't be too hard.

We had quite a few new members to Club Protocab, so there is lots of interest out there. Next newsletter coming out in a couple of weeks. Also the new website should be up and running before the end of the month.

 

Best regards

 

Tony Hagon

Acc+Ess Ltd

 

Developers of the Protocab wireless model railway control system

protocab.com

[StuartM]

Congratulations Tony,

I look forward to seeing the production model on sale soon

I guess this is currently designed for the big gauges of 00 and above?

Is it possible to make it work in n ?

Rgds,

Stuart