In premier steam, I explained the number system. So 20-32xx and higher is a pretty good clue it's PS2 3V, but then we double check the product page and manual we just google "20-3311-1" and first hit is the MTH product page for the engine. https://mthtrains.com/20-3311-1
Made in 2008- which is higher than 2004, another clue it most likely is PS2 3V, but again, we check the manual https://mthtrains.com/sites/de...ction/20st15582i.pdf
Front page says
And then we go to the battery backup part of the manual and it's 2 AA 1.5V batteries, not a 9V so that is another way to know it's 3V
We also note the 3V 2 pin style charging jack
Again, the how to know:
#1 in premier steam, ideally 20-31xx-x and higher, but by the time we get to 32 and then we are even more likely to be PS2 3V. The ones to be extra careful with are 20-30xx and some very low number 20-31xx where checking the manual and other details is extremely important. For Premier diesels, that number scheme is slightly different example 20-22xx-x is likely PS2 5V with the 9V style battery where I think you have to be further up the number range before 3V. Example 20-2511-1 is a confirmed 5V made it 2004- right on the manual page https://mthtrains.com/sites/de...ction/20dl18392i.pdf
But a 20-2550-1 is a confirmed PS2 3V https://mthtrains.com/sites/de...ction/20dl13940i.pdf
So somewhere in there, between 20-2511 and 20-2550, there is a line between 5 and 3 Volt.
#2 never go off number alone. It is advised to then check the manual for the replacement battery type section and charging port type.
