Bob Delbridge posted:Fixed a mistake in my post...the 4-8-4 611 had an 11.1v LiPo battery pack installed, not 9.6v, but changing it to a 12v did up the speed from 48mph to 54mph.
Most of my other engines use a 9.6v battery and run fine.
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I could put a larger battery in the 4-8-4 with that huge tender, but I see no need. I think the motor in the 4-8-4 is the same as in the other Williams engines I have (two 2-8-2 and two 4-6-2). The 3rd Rail E7 has a big 12v Canon motor while the others are MTH and Atlas and all have a smaller motor(s) in them.
O-gauge engines use a bridge-rectifier to convert the AC-to-DC. Even if you apply DC (e.g., from a battery), the bridge rectifier is still in-circuit and drops the battery voltage by 1.5-2V. So using your 11.1V battery, the DC motor will see, at most, around 9-10V DC. The 6 smPH increase by upping the battery voltage by 0.9V (11.1 to 12) is a reasonable estimate for additional speed you'd get by additionally increasing the battery voltage. In other words 6 sMPH/0.9V = 6.6 sMPH/Volt.
It appears you have a 3-cell LiPo pack or 3 x 3.7V = 11.1V. If you can find a 4-cell LiPo pack (14.8V) you'd have an additional 3.7V and your top speed would go up by 24 sMPH (or so).
There is no such thing as a 12V motor per se. A motor is just a bunch of wire, magnets, and metal. It's just that a "12V motor" happens to operate with practical characteristics (RPM, Torque, etc.) when driven by 12V. There is plenty of operational capability at other than 12V.
