Large Scale Central

Getting ready to do my first battery conversion and need some assistance please [SOLVED]


I’ve decided to dive in a try my hand at my first battery conversion. I will be installing the decoder, batteries etc into an LGB 20232 stubby locomotive and tender. I will be using the Blunami 4408 decoder, HJE 14.8v 3350 Mah Lithuim-ion battery and HJE 14.8v Lithuim-ion battery charger . I have a charger plug and toggle switch harness to plug the charger into and toggle the loco on and off. I’ve attached an image of all the items.

I will NOT be running any track power for the locomotive however, I’ve removed the tender pickup brushes and am getting ready to remove the loco pickup shoes. I am not sure which wires go to the pickup brushes on the loco. Does anyone have any guidance, picture and or videos demonstrating on how to do a battery conversion on this locomotive or any LGB Mogul?


Looks like you are not going to have sound as I do not see a speaker and a sound module in the picture. I run Rail Pro it’s all in one, the average cost per engine is around $265 for everything. You do have to buy one hand controller for $310, or you can run with your computer and the Rail Pro module for $35 plugged in the computer. I have two LGB Moguls with Rail Pro installed, one of the biggest things I noticed was how slow the engine will run and super smooth with no jerking. I did remove all pickups and the brass bar that runs between the driver on the mogul as the engine will short out if you don’t, thus you can run your engine on a track power track with no problem. I’m not familiar with your setup, but I feel it should work like the manufacture says, per there instructions.

Suggest you spend some time reading this:

At some point I’ll be converting my two pieces of large scale equipment (an Aristo C16, and a Bachmann Peter Witt streetcar) to deadrail, along with a few O scale locomotives. From what I can gather so far, the Blunami unit seems to be a great solution. The one thing it isn’t suited for apparently is synchronized chuffing sounds if you want that feature for steam locomotives.

Sound is not that big a thing for me, so the Blunami unit looks very promising.

Looking forward to seeing what people come up with. I used to be an infrequent contributor on mylargescale, but this is my first post on this forum. I’m absolutely blown away by some of the great modeling/scratchbuilding on display in large scale!

Jeff C

Then welcome aboard Jeff. Look forward to a pleasant experience here. :sunglasses:

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You can find info on LGB Mogul conversions and lots of other useful stuff here …
And don’t forget to check out G-Scale Graphics RailBoss 4 and MyLocoSound for all of your installations.

i will indeed have sound. The Blunami 4408 decoder pictured has sound. I also have a speaker which is not pictured. I already have all the items needed to make this conversion so am not looking for other solutions at this time. I just need some guidance on how to proceed here.

Looks like that is pertaining to DCC. I won’t be running DCC or DC. The plan is to run off battery power.

Timmy, what Jeff was referring to was ‘synchronized’ sound. A real steam engine chuffs as the cylinders fill and exhaust with steam from the boiler. Some sound cards allow you to connect a ‘chuff trigger’ to synchronize the chuffs with the wheels. Some locomotives (e.g. Bachmann 4-4-0, C-19) come with a chuff trigger installed.
Other sound cards fake the synchronizing by chuffing at a rate based on the voltage to the motor. That’s what the Blunami does:
Place the locomotive on level track and increase the throttle from zero. If the chuff rate does not match the wheel rotations, enter higher or lower values into CV 114 until synchronized. The decoder will automatically adjust the cadence of the chuff to compensate for changes in motor load and speed.
I find this to be quite acceptable, so you can decide when you hear it running.

Timmy, when you say things like that we worry about your depth of knowledge.
Your battery produces how many volts DC? Interesting that it only says 14.8V, not 14.8VDC! So you WILL be running on DC. And DCC!

Almost all model train motors work from variable DC power - the more volts, the faster they spin and the faster the loco moves.
A DCC system, like your Blunami, also is a DC output and input system. It just controls the voltage to the loco differently from e.g. a power pack at the side of the track. If you think about it, your control system (Blunami board) takes fixed battery power in at 14.8V DC and outputs 0 to 14.8VDC (approx) depending on what throttle setting you are using on your controller/phone.

I applogize if you are worried about ‘my depth of knowledge’. As I’ve stated, I never done a track power to battery power conversion before.

So with that said… I am looking for the most straight forward instructions on how to make this conversion using the items I’ve listed.

I would love to see an explicit diagram of how to do this but so far have not found one.

I also have some questions:
• Can I wire the Soundtraxx (Blunami) decoder from the tender through the locomotive’s factory circuit board in the loco or whether it should be removed and wired directly to the motor block’s motor and other devices (smoker, lights)?
• If I am able to install the Blunami into the tender and connect to the circuit board existing in the locomotive would I need a special wire harness between the loco and the tender or is it possible to use the existing cable connection between the 2 and wire into the Blunami?
• I also have an LGB stubby Christmas locomotive and tender that does NOT have a sound decoder in it. This actually is the one that I would prefer to convert to battery power. But I didn’t want to possibly screw up the installation on this locomotive. However, I am wondering if it would be easier to wire up the Blunami decoder to it instead of the 20232?


Timmy, as mentioned before, the Motor Output of your Blunami is variable DC voltage - just like the track power supply. There is no reason you can’t feed the Blunami Motor Output to the engine using the existing wiring in the loco.

No. Use what is there. From the diagrams, all you need to do in the loco is disconnect the wire from the motor block track pickups. You may need to snip it a it seems to be a flat cable with motor power as well. (Don’t cut the motor power leads.)

So to summarize, you need to open the loco to get at the 4-pin wire to the motor block, and disconnect the track pickups. Then, in the tender, identify the wire from the track pickups on the tender wheels and disconnect/snip it. Connect the Blunami output to those same wires on the engine-tender connector, so the engine thinks the Blunami is track power.

Yes, there is a 4 wire flat cable from the onboard circuit board in the boiler to the motor block. Any idea as to which of the 4 wires is the Hot and Common to the motor?

I believe I isolated the Hot and Common pins for the wheel brush pickups in the tender in the plug in the tender that the 5 wire flat cable from the locomotive plugs into. In the image below the RED arrow is where the RED wire from the tender brush pickup connects and the BLACK arrow is where the BLACK wire from the brush pickups in the tender connects to.

No, but Dan does - I think he said the outer pair are motor and the inner pair are pickups (but don’t take my word for it!)

It’s easy to find out - just use your meter to test the pairs. The track pickups should show 0 ohms as you disconnected the pickups, and the motor will show some value, maybe 10 or 20 ohms.

A useful tool is a 12VDC power pack on your bench - mine came from eBay for $5. Add a couple of alligator clips to the DC output, and you can feed the motor to see if it works.

The battery conversion is completed! The Blunami was much easier than I anticiapted. I am ready to convert more of my locomotives in preperation to move my railroad outside :slightly_smiling_face:

Thanks all for the insite and suggestions.