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RailPro Specific Help & Discussion / Over Amp motor issue with LM-4S-G
« Last post by blwloco on July 16, 2026, 10:01:07 AM »Hello RailPro forum! My name is Nick Bulgarino, and I have a model repair shop that installs dead rail systems. I am new to RailPro, and I am running into an issue with the motor control.
There are two issues I have: the first is low speed control; the second is over amping the circuit.
The locomotive, even if I change the start voltage, will not move until I reach 20% or higher. Then it'll jolt forward. I can bring the speed back down and control it, but that's not very prototypical. I am trying to figure out how to fix this, but the manual does not cover this issue.
The locomotive has a stall current of 3.4 amps. The LS-4S-G is advertised to handle up to 8 amps. I am getting an over current error when operating the engine under medium to long train lengths even after doing the Motor Full Load Current test. The test puts the motor current at 750mA to 850mA. That is well below the threshold I think. In order to operate the engine, I have to limit the top speed to 45%. This is too slow for most operations and lacks the power to pull a train up grade.
My question is what am I missing?
Thank you!
There are two issues I have: the first is low speed control; the second is over amping the circuit.
The locomotive, even if I change the start voltage, will not move until I reach 20% or higher. Then it'll jolt forward. I can bring the speed back down and control it, but that's not very prototypical. I am trying to figure out how to fix this, but the manual does not cover this issue.
The locomotive has a stall current of 3.4 amps. The LS-4S-G is advertised to handle up to 8 amps. I am getting an over current error when operating the engine under medium to long train lengths even after doing the Motor Full Load Current test. The test puts the motor current at 750mA to 850mA. That is well below the threshold I think. In order to operate the engine, I have to limit the top speed to 45%. This is too slow for most operations and lacks the power to pull a train up grade.
My question is what am I missing?
Thank you!