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Adventures In Radio Control


PenrithBeacon
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Thanks for that. I do have a voltage booster in stock, perhaps that's the way to go.

I noticed in your post above you use the term balance charging. On the 2S batteries I've looked at on eBay they have a balance lead and a discharge lead so I'm wondering if I might need to have two charging sockets on the model if I use a 2S battery with a balance lead, ie one for charging, one for balancing.

If that's the case it's a question of wiring in the booster or changing the motor to a 6v one

Cheers

David

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Usually with multiple LiPos the connections to each cell are brought out at the charging point - so a 2S LiPo will have three wires at the charging socket. In effect this allows each cell to be charged separately - which is what balance charging is.

 

Compared to  model airplanes or racing boats or cars model trains are very gentle on batteries and balance-charging may not be necessary every time. However if you have a proper charger for a 2S LiPo it is probably simplest to use it all the time.

 

I have 1S LiPos and a voltage booster (boosting to 5.5v) for Kato n-gauge tram chassis in 009 locos. I remove the batteries for charging and I made a simple charger using an MCP73831 charge control chip. Because I have very small cells (240mAh) I was afraid that off-the-shelf chargers would provide a too-high charge current.

 

...R

Edited by Robin2
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I've been standardising on 1S batteries so far, but the battery life was so shortened by using voltage step-ups I found that I think I'd rather use tender-mounted 2S batteries in the big locos to get a better turn of speed out of them, though I'm perfectly happy with the little tank locos using 1S and clanking around at 15mph.

 

Glad to hear that the Tx re-calibration was a success :)

Edited by Corbs
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18 hours ago, Robin2 said:

Usually with multiple LiPos the connections to each cell are brought out at the charging point - so a 2S LiPo will have three wires at the charging socket. In effect this allows each cell to be charged separately - which is what balance charging is.

 

Compared to  model airplanes or racing boats or cars model trains are very gentle on batteries and balance-charging may not be necessary every time. However if you have a proper charger for a 2S LiPo it is probably simplest to use it all the time.

 

I have 1S LiPos and a voltage booster (boosting to 5.5v) for Kato n-gauge tram chassis in 009 locos. I remove the batteries for charging and I made a simple charger using an MCP73831 charge control chip. Because I have very small cells (240mAh) I was afraid that off-the-shelf chargers would provide a too-high charge current.

 

...R

Thank you for that.

 

I gather from eBay that although this true from some batteries it isn't true for others , and balancing chargers aren't cheap although they are reasonably so on eBay (although the cheaper ones might not be so reliable).

 

I imagine that most tender locomotives will have sufficient space for PP3, AAA or AA batteries, but my interest doesn't particularly lie there.

 

Now that the Sentinel is finished I'm going to buy more components so I can do the other three locos I have that have been converted to P4.

 

Cheers

 

 

 

 

 

 

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An alternative is to make up your own 2S battery from 2 small single cells and charge them separately but you would need to be able to remove them from the loco. Another idea is to make up your own larger single cell with smaller cells connected in parallel. This acts as if it is a 1S battery and the individual cells automatically balance themselves.

 

How many mA the loco uses in normal service is important. My rule of thumb is if the loco pulling its normal train at normal speed draws less than 250 - 300 mAh then a Pololu booster will do the job with a 1S battery.

 

How do you find the loco power requirements?

 

I am lucky in having a continuous circuit so I charge the battery, couple up the wagons etc and mark the throttle position for normal running. Then charge the battery again and let it run until the Rx LVC stops the train. note how long this took. for example if you have a 250mAh battery and the loco/train runs for an hour the loco is drawing about 250mA.

 

as a refinement my operating sessions last up to 3 hours. I give the loco 30 minutes of moving which needs 125mAh in the above example. My Rx/Pololu combination needs about 20mA when idling so add 2.5 hours of this giving 50mAh for a total battery size of 175mAh. Actually my locos usually only run for 10-20 minutes.

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Casting my mind back further than I would like to, am I right in concluding that if a step-up converter is used, for a given current consumption, the runtime will be reduced, so if we subtract a nominal 15% then double the voltage, we would get roughly 43% of the running time? Or have I got that wrong?

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54 minutes ago, wasdavetheroad said:

...

How do you find the loco power requirements?

...

As a beginner my approach was a lot less sophisticated. I measured up the physical space I had (the loco is tiny) and then searched on eBay for a battery of that size or less with the greatest electrical charge. It came out as 180 uAh.

Now I'll suck it and see. I'll probably run it up against a buffer stop and run it. That way I'll get an idea of how long the charge will last with the motor on full load ie the weight of the loco.

Cheers and thanks for all the advice

David

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  • 1 month later...

Just before the Covid-19 crisis emerged the Sentinel stopped working. After a bit of testing it became clear that the problem lay with the Rx or at least with the ESC part of the PCB. I think I zapped it with handling the thing. 

At the time Micron didn't have any in stock, so I made my interest known and waited. Last week they arrived and now installed ok but this time, in addition to having the power and motor leads soldered on, I had the PCB insulated with heat shrink wrapping. Better safe than sorry.

Cheers

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  • 2 months later...

The second locomotive chassis is almost ready for the RC components to be installed (I'm a slow worker) and I'm wondering about changing the method of connecting the wires.

Then I soldered them together and insulated the joint with heat shrink  sleeves. It was a success but now I'm thinking of using connectors instead. Has anybody got advice, please.

Cheers

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1 hour ago, PenrithBeacon said:

I'm thinking of using connectors instead. Has anybody got advice, please.

Cheers

 

I've standardised on all my 4mm/7mm/16mm rc installations with JST 1.25 plugs and sockets - available in bulk for cheapest prices from ebay chinese suppliers. Might be worth a look for you.

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  • 4 weeks later...

Advice please. At long last, I decided to pursue radio control for my 4mm loft layout. I had decided on Deltang equipment, but have now found that they are discontinuing their receivers, and are looking for a buyer for the trains bit of the company. What lowish cost options are left from other companies?

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1 hour ago, 88D said:

Advice please. At long last, I decided to pursue radio control for my 4mm loft layout. I had decided on Deltang equipment, but have now found that they are discontinuing their receivers, and are looking for a buyer for the trains bit of the company. What lowish cost options are left from other companies?

The DEltang RX6 series will cease production at about the end of the year because the main onboard chip will no longer be available.. David T is looking for someone to continue development of a replacement of the Rx6 Series. I believe all but one of the Rx4 series will continue in production. Micron Radio Control have receivers in development which, because they use the same Spectrum DSM2 protocols as Deltang will be compatible with Deltang transmitters, also Micron transmitters will control existing Deltang receivers. Tony Walsham of Remote Control Systems in Australia also has alternatives available and in development.

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  • 3 weeks later...

Advice again, please. I model in EM, and will be using radio for tank and tender locos. I reckon I’ll use mainly 2x Lipos for tender engines and 1 for the smaller tank engines. What batteries (make, model) do you use, and are you happy with them? Cheers, Dai

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First of all I must say that my experience with BPRC is exactly what you see on this thread, no more no less, so perhaps you are asking the wrong person.

When I was converting the Sentinel the capacity of the battery was constrained by the space available not by any preconceptions of what I thought I needed. I selected an appropriate battery from  the hundreds that are available on ebay. 

2S LIPO batteries need to have both cells charged equally,  this requires a more sophisticated charger costing a lot. Does your tender engine really need that? I think I'd experiment first. A smallish tender engine may well do with ahigh capacity 1S battery, but a 9F might need more, but then you might be able to use a PP3 instead of LIPOs.

I don't think planning too far ahead is worth while,  solve one problem at a time. 

Cheers 

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If the motors in the locomotives are modern and only draw a low current then a voltage step-up module (such as an MT3608) and a 1S LiPo might be the best option as it makes charging easier. Just step up the voltage by the smallest amount that is necessary to get the performance you require.

 

...R

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I use single cell hobby batteries with 'UM' connectors, usually with small voltage regulators. for example you can boost 2 single cell lipos, nominally 7.4 volts to either 9 or 12 volts, or a single cell to say 5 volts. Some locos will be happy with an un boosted battery.

 

I remove my batteries to charge them so I can use single 'UM' battery chargers. I now have the capacity to charge 10 batteries simultaneously and independently, so no need for balance charging, the batteries are all 4.2V after charging. I made up small wiring harnesses in whatever combination I needed.

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12 hours ago, 88D said:

Advice again, please. I model in EM, and will be using radio for tank and tender locos. I reckon I’ll use mainly 2x Lipos for tender engines and 1 for the smaller tank engines. What batteries (make, model) do you use, and are you happy with them? Cheers, Dai

Thanks for your replies on this. You’ve made me think again, which means I’ll probably come along with other questions after my hols! This is where I miss train shows, as you can talk and see in vivo!

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  • 4 months later...

I've been looking on eBay and Amazon for a power pack for rapid charging of 1S Lipo batteries but I can't find anything. Does such a thing exist?

They seem to if you want to charge a phone or tablet but not for RC, the best thing I can come up with is high power 3S batteries. 

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Look for chargers designed for use with small RC planes etc which use 1S batteries, Micron Radio Control have a couple of types. Note that charging is generally recommended to be no more than 1C so a 200mAh battery would have a recommended charge rate of 200mA per hour. RC plane fliers want to charge rapidly but this stresses the battery. I remove the battery for recharging so 'recharge time' is how long it takes to replace the battery with a fresh one, usually about a minute!. My batteries have UM style connectors.

 

http://www.micronradiocontrol.co.uk/charger.html#psu-usb-2a

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  • 1 month later...

Well, a really nice day for me as I’ve just converted my Bachmann 2251 into a radio-controlled Bachmann 2251. Now this is a tender loco, though not a large tender, and I have managed to fit battery, switch, voltage uplifter and receiver into the tender.

My question relates to tank locos, such as panniers and small prairies: do you try to fit all this into the tank loco, or do you forego switch and possibly uplifter. I have bought smaller batteries, receivers, etc for these tanks; but what is your experience of such locos, and do you lose much by not incorporating some of the gizmos? Cheers, Dai

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39 minutes ago, 88D said:

Well, a really nice day for me as I’ve just converted my Bachmann 2251 into a radio-controlled Bachmann 2251. Now this is a tender loco, though not a large tender, and I have managed to fit battery, switch, voltage uplifter and receiver into the tender.

My question relates to tank locos, such as panniers and small prairies: do you try to fit all this into the tank loco, or do you forego switch and possibly uplifter. I have bought smaller batteries, receivers, etc for these tanks; but what is your experience of such locos, and do you lose much by not incorporating some of the gizmos? Cheers, Dai

Well, I spoke too soon. It was all up and running, so I decided to show my son. Didn’t work: it had become ‘unbound’ and doesn’t want to rebind. I’m using the same controller, RX 63 receiver,etc that appears on this thread, so any suggestions. 
I press the buttons in the correct order, but should zi keep them pressed whilst the binding operation is taking place?

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