How To Expert Tips How to replace the battery in an older MTH engine

How to replace the battery in an older MTH engine

By Jim Riccioli | January 25, 2024

| Last updated on December 19, 2024


MTH's original ProtoSound and ProtoSound 2.0 systems can create great anxiety when the systems backfire.

Email Newsletter

Get the newest photos, videos, stories, and more from Trains.com brands. Sign-up for email today!

The age of miniscule computer chips has delivered sweet sounds to modern toy train locomotives. But such systems can add a sour note when they start acting “funny.”

MTH’s original ProtoSound and ProtoSound 2.0 systems can create great anxiety when the systems backfire. The culprit is often a component that’s hardly hi-tech. It’s the battery.

The culprit

locomotive with shell off, battery packs
CTT photo

Although MTH circuitry continuously recharges the battery whenever you run your locomotive, the original factory-installed NiCad (nickel cadmium) battery deteriorates with age until it can no longer hold a charge or reach its full voltage capacity, no matter how long you charge it. At this point, the battery must be replaced.

MTH reports that fully a third of the locomotives returned for repair could be serviced at home by recharging or replacing the battery.

How do you know the battery in your locomotive is going bad?

If your locomotive is several years old, the sounds stop when you interrupt power, the whistle or horn are distorted below 10 volts, or the locomotive will not sequence through forward, neutral, and reverse properly, your locomotive likely has an undercharged battery.

In MTH’s sound systems, a bad NiCad also can create a tech-y problem. As an aging or long-idled battery fails to deliver the voltage needed to allow the sound system to power down properly, the locomotive’s computer chip can get “scrambled” – basically, the software becomes jumbled by the electrical irregularities so that the system can no longer think properly. The net effect is usually that the locomotive stays locked in one direction, or the sound sequences become corrupted. If that’s the case, there’s nothing you can do to get it working properly again except to send the locomotive to MTH, which simply replaces the bad chip.

However, the problem can be avoided entirely by paying attention to the battery before it has a chance to scramble your circuit.

The fix

MTH has this suggestion: If you haven’t run a ProtoSound-equipped locomotive for a few months, charge the battery before running the locomotive and cycling through the various sounds. You can charge the battery by removing it and sticking it in the appropriate battery charger (such as MTH No. 50-1005 or battery chargers sold at  Wal-Mart, among other places). Or simply put the engine in neutral on the track and turn the throttle to 15 volts for 14-16 hours. You can also do a quick charge for an hour using the same procedures and then test the locomotive to see if the battery and sound system are functioning properly, and then finish charging it later.

If the battery is bad, obtain a new NiCad from MTH or replace the NiCad with an 8.4-volt 150-mAh Nickel Metal Hydride (NiMH) rechargeable battery. NiMH batteries don’t usually exhibit the “memory” problem of older NiCads. If you’ve ever had a cordless vacuum or rechargeable screwdriver “go bad” you’ve faced this problem before. Some operators prefer Rayovac’s NM1604-1, available at Wal-Mart and other retailers.

Beware of 9-volt rechargeable batteries that don’t deliver at least 8.4 volts when fully charged. Energizer only lists a 7.2-volt rechargeable NiMH battery, which is not adequate for MTH’s system.

How to do it

Removing the old battery and installing a new one is easy. The battery is attached to the typical wire harness/connector that you see in appliances which use 9-volt batteries. Simply charge the new battery as directed, remove the locomotive shell, and have at it.

Like MTH, you may want to use a piece of mounting or servo tape (double-sided padded adhesive tape such as the type used in radio control models available at hobby shops) if you want to secure a loose battery in its proper position. Refer to your locomotive’s manual on how to remove the shell.

MTH’s design generally requires that the battery be present for the locomotive to work at all. (There are some exceptions with MTH ProtoSound-equipped locomotives made before 1998). So, if you own an MTH locomotive with sounds, you’ll have to deal with the battery sooner or later. Sooner is better.

22 thoughts on “How to replace the battery in an older MTH engine

  1. WoW!! Brilliant! !! The problem is figuring out how to get to the battery in their o gauge tinplate tender. After removing all the found screws, nothing comes apart to reveal the battery. Whats the secret password ??

  2. Lionel type 1039, received Dec,1942, 35 watt transformer. Giving to grandson, need to know how, where to charge
    battery or get new one. Thank you.

  3. Phil G., Contact the good folks at MTH customer service ( early afternoon EDT is best) and ask to speak with a service technician. They will be glad to talk you through the shell removal. Even though I only live a half hour's ride to MTH headquarters in Columbia,MD, I have always been able to solve any issues over the phone,right at my home workbench! P.s My favorite source of Tinplate Traditions trains& stuff is Sidetrack Hobbies in Leonardtown,MD(Sidetrackhobbies.com) check em' out!

  4. Hi Phil, I looked at the manual (available on the MTH website) and I'll be darned if I could find the "how-to" part about removing the shell. While I might suppose the screws holding the boiler on the model might be obvious, I generally hesitate before I start unscrewing things at random. You might want to try and contact MTH service for help. FWIW they also have the manual for the early ProtoSound engines online and they contained the notation that if the battery needed to be changed, contact MTH to return the product for repair.

  5. For what it's worth, I bought an MTH Pennsy Doodlebug on Ebay and all it would do is sit on the track with the motor sounds running. I saw your forum about it and I purchased an Energizer 9 volt rechargeable for $10 at Walmart. It solved the problem completely.

  6. Some of the newer MTH locomotives have an external power charging plug. Before taking it apart, check. I replaced the dead NiCads with the newer NiMH and they seem to work better. I'd suggest buying the MTH charger so you get one that works. If you replace the batteries be sure and charge up the new ones before placing them in the loco. I used the MTH 50-1008 NiMH batteries and the MTH 50-1019 charger. The battery is an 8.4 volt in a 9 volt size. My locos are Lionel Tinplate standard gauge made by MTH. One of my locos has the external charging plug so I used the 50-1019 charger to charge the new battery using the external plug.

  7. I'm not too mechanically inclined. How difficult is it to recognize the battery and to replace??

    Also, I believe I have 3 engines that need batt replacement. I hope I can do this.

  8. I was under the impression that only original Proto Sound by QSI demonstrated these tendencies and PS-2 solved the scrambling issue. My NW Switcher w/PS-2 demonstrates all the characteristics mentioned here so I guess I'm sending it to MTH for de-scrambling.

  9. Hello all, Thank you for the great help. My 10 yr old son and I are getting into the O gauge hobby. I'm no stranger to model trains, as I have Marklin from the 50's and 60's that my grand father left me. Anyway, my question is. Can I use the 50-1019 MTH charger? Is it the same as the 50-1005, but with 2 charging ends? Thank you Paul Jr and son

  10. I would like to know the item/SKU numbers for the battery chargers offered by Radio Shack and Wal Mart. I have just purchased 3 older Protosound 1 engines from a dealer and already have problems with the batteries. I have a charger, however, when I put the protosound battery in to charge, the charger does not let me know when the battery is charged. Thankyou, and keep up the good work on Classic Toy Train Magazine.

  11. Thanks. At my Radio Shack the stock number noted above has been replaced by the brand name "enercell" rechargeable battery, item number 23-748.

  12. The BCR by J and W Electronics is the way to go! I have 40 of them and they have never let me down. They also have a BCR for the newer Proto Sound 2 engines.

  13. Or you can relace the battery with the capacitor sold by J and W Electronics. I always felt the MTH battery problem was a design flaw. If the fix was to add something as simple as the product sold by J and W it should have been included from the beginning. I'm down to two MTH locos left. Both have the J and W "battery". No problems ever.

  14. This is a very good article (definitely a "4"). It would have been a "5" had the author also included the Item/SKU numbers for the battery chargers offered by Radio Shack and Wal Mart.

    Never the less; this article has been of GREAT help to me and should help other just as much! Thank you for taking the time to create such an informative article.

You must login to submit a comment