Replace Sierra Gel Cell with NiMH Battery

1a-SierraSoundSystemLike many, many model railroaders I have an engine equipped with a Sierra sound system. These sound systems, now discontinued in Large Scale, work great, were very popular, and came with a 6-volt gel cell lead-acid battery that provided power to drive the sound card. These batteries recharged from the track power (if you where running enough juice through the tracks) or you could recharge them using an optional power jack.

These systems worked well and all was right in the model train world.

Ah, but nothing is perfect and there is a problem with the gel cell lead-acid batteries. They tend to discharge quickly if left on the shelf, unused, for any length of time. And I only run trains sporadically depending on the demands of family, work, and weather. That would be okay except if left in a discharged state the gel cell will “sulfate” and become unusable.

After replacing the gel cell battery three times I started searching for a better solution. And I found one.

Now, I did not figure any of this stuff out on my own. I’m somewhat electrically challenged when it comes to ohms, and volts, and circuits, oh my! And lead-acid sulfation issues. But I am armed with a great list of resource sites and so I turned to the train guru, George Schreyer, and found that he had beaten this path before me. On George’s site I learned about gel cells and that they are prone to sulfate problems that left them unusable and George had fashioned himself a solution.

George took (5) NiMH batteries and soldered and shrink-wrapped himself a custom battery pack and replaced the gel cell in his Sierra sound systems. To quote George, “The NiMH (Nickel Metal Hydride) technology is the most resistant of any of the available technologies to being left flat, partially charged or partially discharged or recharged from a partially discharged state.” In other words, if you let them go flat you can just recharge them again and they’ll work. My kind of solution.

What’s more, according to George, “ These NiMH cells are rated at 1650 mAh… this kind of pack has about the same volume and weight as the stock battery, [and] it’ll run the system up to 3 times as long between charges. It’ll also take 3 times longer to fully recharge.”

For reasons stated above I decided to take George’s word for it. But how was I, who actually owns a soldering iron but can only manage to tin stranded wire together manage to make custom battery packs? This time the solution was at my local hobby shop. I had told Roy, at Roy’s Trains about George’s solution and Roy was interested because a number of his customers had the same issue. Roy found a source of (5) cell battery packs that were plug and play and would be a straight-up replacement for the gel cell.

1-upsidedownShayArmed with a new NiMH cell pack from Roy, I was ready to screw my courage to the sticking place and deal with my dead gel cell.

I mounted my Shay in my upside down engine holder (see Working on an Engine – Upside down) and was ready to do surgery.


My Sierra sound system was installed by Dave Goodson (a giant in the train hobby) and on Dave’s installations the gel cell is mounted on the undercarriage of the Bachmann Shay.




Snip, snip, and the old, dead, gel cell was removed to make room for the new NiMH battery pack.




The NiMH battery pack that Roy has stocked comes with a Tamiya female quick connect attached to the plus and minus leads. I stopped by Radio Shack and found they had the corresponding male connector (actually I had to buy a set of leads, male and female) in their RC 9.6V Battery Pack Connector Repair Kit (Model: 23-445, Catalog #: 23-445).  At $6 for the connector and $15 for the NiMH batteries I thought it was a bit pricey but since the gel cells alone were costing me $25+ bucks a crack I guess everything is relative.


As George pointed out in his white paper the form factor between the gel cell and the appropriate number of NiMH cells is nearly identical. I found that on my (2) truck Bachmann Shay that the NiMH cell pack fit perfectly in in the frame carriage where the gel cell was located.


The Radio Shack male connector is equipped with the leads where you just slip in the bare wire and crimp the plastic connector to attach and make a solid contact. Since the old wires were the stranded (not solid core) type I actually did heat up the soldering iron and tin the strands before attaching.

The quick connect/disconnect plugs are way too large in my opinion and if I were handier I would have replaced them with something smaller. But I managed with it as it was.

5-paintedbatteryAs you can see above, the NiMH cells are packaged in a bright lime green wrapper and the quick disconnect is huge and made of white plastic. Now it’s all underneath the Shay and therefore should not be visible but most of my layout is raised off the ground, so I touched up all the exposed bits with some black acrylic hobby paint.



Once painted even a shot from the track level looking up (and the Shay mounted up on rollers) does not show anything untoward.

Sound system is now back online and working great! I’ve not yet run the battery down and tried to recharge via the recharging jack but I don’t anticipate any problems with that.

You can read George Schreyer’s white paper on this topic here:

Sierra Battery Issues

You can contact Dave Goodson about RC battery and sound installations though his Web site here:

Northwest Remote Control

Unfortunately you can no longer reach Roy at Roy’s Trains since this local hobby shop has gone the way of most things from my youth and is out of business. But you may still be able to reach Roy through his Web site here as it was still active last time I checked:

Roy’s Trains

Let me know what you think! – TJ

(Originally posted 9/30/2011, revised 5/10/2013)

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2 Responses to Replace Sierra Gel Cell with NiMH Battery

  1. Hines says:

    How neat! Is it really this smpile? You make it look easy.

  2. Roy Ogle says:

    The batteries are located under ‘Featured Items’ in ‘G Scale’ at the website.

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