Converting Accucraft K-27 to battery r/c

maxi-model

maxi-model

UK/US/ROW steam narrow gauge railways 1:1
Country flag
I have an older version track powered Accucraft K-27, the one with the right rail pickups only on the 4 tender wheels and the left likewise on that side's 4 driving wheels only. The loco has a functioning Sierra Soundtraxx sound card fitted. Most sounds are voltage activated but the chuff and a couple of other sounds are reed switch activated.

I have the published manuals for both the loco and the sound card. The sound card's has a full wiring diagram but the loco does not. I have searched the web for the latter but to no avail. I did find an article, authored by Tony Walsham of this parish, but it is not clear as to how he (re)arranged the power supply to the motor and isolated the pickups on this specific loco type when doing a similar conversion some years ago.

As I understand it replacing the track pickups' voltage inputs to the sound card is fairly simple - replace input from track pickups with those from one of the 2 pairs from the esc. What I am not sure about is how to isolate the motor (and possibly chassis too) from track induced voltage inputs and how best to attach the esc voltage input to the motor. There is a terminal block accessible under the ashpan where a number of wires coalesce for power distribution on the loco itself.

Questions - Am I right in the assumptions I have made so far and how do I isolate the track pickups on the loco (tender is self evident) and connect the motor to the esc without ripping the loco to bits ? Your assistance and suggestions would be most welcome.

20181030_181837.jpg

A picture showing the terminal block under the loco's ashpan. As a point of note I have acquired all the conversion gubbins from Fosworks - A Cobra high frequency 6 - 24v speed controller, 14 cell AA NiMH battery pack with 5 amp fuse, Omni Tx-2.0 tramsmitter, Omni RX-2H receiver and assorted other parts for charging and wiring. Max
 
Last edited:
Hi Max
I think that you have the correct way forward.
In case you do not have it to hand, here is the section form the manual about DCC and also a vid by Peter Spoerer about RC installation in an Accy K27.


k27 dcc.jpg
 
Max would have been interesting to see that underneath panel removed to see how the wiring is within the loco Ashpan Distribution point. Perhaps it would be evident instantly or possibly not. However if there are screw fittings within it should be relatively easy to isolate the Wheel Pickup Wires. These could then possibly be linked to the Tender Pickup ones and routed via a DPDT CO Switch so that the Loco could be Track or Battery Powered. Nice to see you exploringbthe dark side in a Big Way! Mudhen will be a great Battery Loco.
 
beavercreek said:
I think that you have the correct way forward.In case you do not have it to hand, here is the section form the manual about DCC and also a vid by Peter Spoerer about RC installation in an Accy K27
Click to expand...

Thanks Mike. I have the manual and inwardly digested it. However it does not give me the information I am looking for to go forward with confidence - How the loco is wired from pickups to motor. Remember its not like a regular loco with all wheels on both sides picking up. I've looked at the video and it only listing what bits Peter Spoerer has installed, mostly the same/similar stuff I'm putting in, not how. Oh, and how to change the whistle to a bell sound on the supplied sound card. Max

View attachment 245042ve the manual and have read it, there is nothing as to how the loco is wired or how the pick ups located and connected to the
 
dunnyrail said:
Max would have been interesting to see that underneath panel removed to see how the wiring is within the loco Ashpan Distribution point. Perhaps it would be evident instantly or possibly not. However if there are screw fittings within it should be relatively easy to isolate the Wheel Pickup Wires. These could then possibly be linked to the Tender Pickup ones and routed via a DPDT CO Switch so that the Loco could be Track or Battery Powered. Nice to see you exploringbthe dark side in a Big Way! Mudhen will be a great Battery Loco.
Click to expand...

Thanks Jon, looks like I'm going to have to pull at least a little bit of it apart. My plan is to run it a battery only. Not quite sure what a "DPDT CO" switch is and how it would be wired but I guess I won't need one if I am not retaining the track power function. Max
 
maxi-model said:
Thanks Mike. I have the manual and inwardly digested it. However it does not give me the information I am looking for to go forward with confidence - How the loco is wired from pickups to motor. Remember its not like a regular loco with all wheels on both sides picking up. I've looked at the video and it only listing what bits Peter Spoerer has installed, mostly the same/similar stuff I'm putting in, not how. Oh, and how to change the whistle to a bell sound on the supplied sound card. Max

View attachment 245042ve the manual and have read it, there is nothing as to how the loco is wired or how the pick ups located and connected to the
Click to expand...
Yeah, there is the possibility that the chassis / body of the loco is 'live' - although there's got to be some trickery in the coupling bar if the tender picks up the other way :think::think::think::think:
 
PhilP said:
The body is not 'live', unless there is a trapped wire! :nerd::nod:
Click to expand...
All depends - back in the 'good ole days' when I built white metal 00 locos for a local model shop to sell, you only had one insulated wheel per axle, and therefore only had to have current collection on one side - the rest of the loco was 'live'.

Generally, tender axles had both wheels insulated :nod::nod:

Obviously, only in auntielogue :nerd::nerd::nerd:
 
Rhinochugger said:
Yeah, there is the possibility that the chassis / body of the loco is 'live' - although there's got to be some trickery in the coupling bar if the tender picks up the other way :think::think::think::think:
Click to expand...

I had heard rumors of this. It was a common practice with "all metal" locos. The tender and loco are insulated from each other via the draw bar. It has been suggested to me (from where I remember not) that there may be some kind of direct connection between chassis and one of the motor inputs, not just a wire. Max
 
maxi-model said:
I had heard rumors of this. It was a common practice with "all metal" locos. The tender and loco are insulated from each other via the draw bar. It has been suggested to me (from where I remember not) that there may be some kind of direct connection between chassis and one of the motor inputs, not just a wire. Max
Click to expand...
Whatever, it's strange, 'cos there's no logic in the tender pickup being the other side - you've either limited the number of current collection points or made things unnecessarily complex ............. or both :emo::emo:

Obviously using the car body wiring principle it allows for a lot less spaghetti inside the loco - which must be a good thing >:)>:)>:)
 
Rhinochugger said:
Whatever, it's strange, 'cos there's no logic in the tender pickup being the other side - you've either limited the number of current collection points or made things unnecessarily complex ............. or both :emo::emo: Obviously using the car body wiring principle it allows for a lot less spaghetti inside the loco - which must be a good thing >:)>:)>:)
Click to expand...
Re Tender one Rail Pick Up on one rail and Loco the other one. This was a fairly common practice for Tender Locomotives in smaller scales a good few years back. Saved on wiring and apparently made things easier. I have never been keen on the practice. MAX, DPDT CO Double Throw Double Pole Centre Off Switch. Allows 2 wires from Pickup and 2 wires from Battery to be swopped so that the Centre Switch Contacts go to the guts of the Loco thus giving the option of either Battery or Track Power. Well worth thinking about if you are concerned about resale value. The Off bit saves any potential flashover when changing between the modes. Personally thus far like you I just forget the Track Power. However for my future DCC Locomotives when I convert them to Battery Power a DPDT CO will be incorporated so that I can use my DCC Setup if I wish to change any CV’s. Though one of the optione that I will be using (Aristocraft) has CV update capability the other one (my preferred option Fosworks) does not.
 
Greg Elmassian said:
can't find wiring diagram? Well, the term is schematic for electronic engineers

...google "bachmann k27 schematic"

you will find it...

(and it's on my site as well as other places)

Been there for years."

Greg
Click to expand...

Greg -

The loco I have is an Accucraft not a Bachmann make and as an early version has a different pick up arrangement to a regular "plastic" K-27 or even later model Accucraft K-27 and that affects the wiring schematics .

Not that I wish to alienate one who is so generous and erudite in their responses, and from which I have benefitted, but as you are so fond of reminding those who miss the mark when responding to posts - please refer back to my initial post :)

But I am very grateful for your offering the term "schematic" as providing the possibility for better/additional search results to that of "diagram". Max

General note - Try not to be patronising in your responses, especially when you have got the wrong end of the stick yourself. It may cause the issue, as you may be seen by other members of this community as one of the "fonts of all knowledge in these things", that others will think the original poster has either been a bit remiss in their initial research or assumptions before posting or a complete numpty (I'll personally take the 5th, as some might say, on that last one).
 
Just had a very nice conversation with Chris Sortina, an Accucraft service agent. I e-mailed Accucraft US yesterday (Sunday !) and got an almost immediate response. Now that is what I call service.

It appears that the factory in China is very loath to giving out any of the electrical schematics of their locos. So, there aren't any available from the US. However, he agreed that the terminal block, shown in the picture at the head of this thread, is probably laid out with the 2 innermost posts/terminals being for the motor and the outermost being those supplying power to the lights.

He said poking about with a couple of power leads from my controller, so long as the voltage is kept below 6v, should not risk doing any permanent damage to any stuff on the loco (impressed with my technical language ? :rofl: ). Chris was not able to confirm if the loco was grounded through the frame. Seeing as I will never run it on "live rails" and all my stock (of necessity) has insulated wheels this should not be a problem.

So I'll just have to give it a go and hope for the best. Jon - not sure how I would incorporate a DPDT CO switch here, if even possible, but I'll keep all the bits (tender wheel pick ups) so any future owner can convert it back to track power. If anybody thinks I'm about to do something utterly dumb please feel free to alert me.

For those who like these sort of this here's a picture of the bits being used for the battery r/c conversion. Max

20181105_174937.jpg

I have acquired all the conversion gubbins from UK company Fosworks - A Cobra high frequency 6 - 24v speed controller (made for DC motors), 14 cell AA NiMH battery pack with 5 amp fuse, Omni Tx-2.0 transmitter (nice little palm of hand unit), Omni RX-2H receiver and assorted other parts for charging and wiring.
 
Last edited:
Advice is same as on other forum, simplified, do direct route of motor and lights to the tender, and then make sure that none of these wires have any connection the the metal chassis of either the loco or tender (ohm meter)... in mine, the voltage regulator for the headlight was connected to the frame of the loco... and well hidden!

There were also interconnections between motor and some lights in the loco, so you want to be sure they are isolated.

You did not show a picture, but do you have the big multi-pin connector between tender and loco?

Greg
 
Hi Max
Your K27 is one of Accucraft's early models and does not have the multipin plug and socket. that Greg is referring to. The multipin appears in their next stage locos manufactured after the K27 and C16 (first run).
Do test the loco body to see if the single-side track pick-up is insulated and just goes directly to the terminal block in your photo (to feed motor and lighting regulator in the the smoke box) or does indeed make the body 'live'.
If I remember correctly, on the loco when it was in my ownership, the draw bar is insulated and the red plugged cable carries the single-side power pickup feed from the tender to the loco and also the single return from the loco feed back to the rear light.
 
maxi-model said:
Just had a very nice conversation with Chris Sortina, an Accucraft service agent. I e-mailed Accucraft US yesterday (Sunday !) and got an almost immediate response. Now that is what I call service. It appears that the factory in China is very loath to giving out any of the electrical schematics of their locos. So, there aren't any available from the US. However, he agreed that the terminal block, shown in the picture at the head of this thread, is probably laid out with the 2 innermost posts/terminals being for the motor and the outermost being those supplying power to the lights. He said poking about with a couple of power leads from my controller, so long as the voltage is kept below 6v, should not risk doing any permanent damage to any stuff on the loco (impressed with my technical language ? :rofl: ). Chris was not able to confirm if the loco was grounded through the frame. Seeing as I will never run it on "live rails" and all my stock (of necessity) has insulated wheels this should not be a problem. So I'll just have to give it a go and hope for the best. Jon - not sure how I would incorporate a DPDT CO switch here, if even possible, but I'll keep all the bits (tender wheel pick ups) so any future owner can convert it back to track power. If anybody thinks I'm about to do something utterly dumb please feel free to alert me. For those who like these sort of this here's a picture of the bits being used for the battery r/c conversion. Max View attachment 245219 I have acquired all the conversion gubbins from UK company Fosworks - A Cobra high frequency 6 - 24v speed controller (made for DC motors), 14 cell AA NiMH battery pack with 5 amp fuse, Omni Tx-2.0 transmitter (nice little palm of hand unit), Omni RX-2H receiver and assorted other parts for charging and wiring.
Click to expand...
Hi Max I add my rough reminder diagram to Show how I connect things up. Note the Red PNP Plugs on the Wiring Loom that I have labelled Male and Female. The Male to the Motor with ‘Wire Required’ will be the one that is wired in to a DPDT CO if you use one.
1538A971-FB3C-4174-9851-2E3DB523EFE8.jpeg
So here is how I would use that DPDT CO if you put one in. I note the issues that you may have with the Accy Loco’s wiring. Personally I think I would be gutting the beast to get at the Motor Directly but by the sounds if things that may be tricky.
82866F91-008B-4E5A-A645-251F1CFCA85B.png
Also note on my diagram if you pull the Cobra and the RX2 apart how the wires are orientated, you have them correct in your picture. Get that 3 pin plug the wrong way round and you will trash something, don't ask how I know?

There are 4 wires from the Cobra that are not connected to anything Red, Black, Blue and Yellow (shown green on my diagram) these as you see are for a Soundcard. If you do not have one suggest that you either Heat Shrink or Wire into a spare piece of Terminal Block to stop them shorting between each other.

Hope this helps Max.
 
Last edited:
I'm getting a clearer picture in my head now Mike, I think I am starting to see how this will all work and be plumbed in ( i find it easier to understand with the flowing water metaphor :think: ). I've got the insulated drawbar assembly off and have clear sight of the "terminal block" under the "firebox" and its arrangement. All will become clearer when I get the pic up that Greg has requested. Yes, the bit that still worries me is that the loco body is "live".

Thank you for the schematic Jon. I just plugged it all up for the photo op, nothing is switched on. However there is a problem with the wiring of the Cobra esc as supplied. I think there was a misunderstanding when I asked for 2 sets of long wires for the motor and sound card voltage controlled sounds. They should both be coming from the output terminals marked MOT on the esc. There should not be two pairs on the input side, marked +ve/-ve. Not sure why I would want to pump the full voltage of my battery pack constantly into the motor or sound trigger circuit on the Sierra sound card. I've also got the wrong switcher unit for the, presently, reed switch activated sounds. I begin to despair :giggle:.

Greg I will be back with pictures in a while - got some socialising to do today and my car goes in for its annual service and roadworthiness test tomorrow. Max
 
Last edited:
Max,
I think you may have problems with the existing Sierra Sound card??

Don't think it will like a PWM motor voltage from the Cobra..
 
You must log in or register to reply here.
Back
Top Bottom