I am planning on getting a new motor setup for one of my planes and was wondering that when a motor says its rated for 2-4s lipo does that mean the voltage equivalent or does it mean that you cannot put more than 4 cells lipo into the motor no mater the configuration?
thanks

Well, both really. The cell count determines the voltage going into the motor/ESC. Voltage determines the RPM that the motor will turn, and the load on the motor determines how many amps it will pull. If you put too much voltage for the load (prop) you are using, you'll burn up your motor or ESC with too much current. So motor combos are rated for a certain voltage range which will correspond to a certain Lipo cell count since that's what nearly everyone uses now. Often, a motor's specs will give you the right props to use with each battery cell count to keep the amps down to what the motor can handle.

so I wouldn't be able to run Hypothetically 4 batteries each 2s into a motor rated for up to 4s even if i ran 2 pairs of the batteries in serial then ran those pairs in parrallel to get voltage that would be equivalent to 4s but also have a higher Mah/capacity?

The way I see it is if you run 4 2s, 2 of them in series and 2 of them parallel you should be ok if I'm understanding your question correctly. I'm no ESC guru so let someone else chime in, but think about it like this...if you have an esc capable of 2s you can run 2 2s in parallel to keep the voltage the same and just adding capacity. The esc still reads it as a 2s and voltage, LVC, etc should still be good.

Some on the subject here.
https://www.rcgroups.com/forums/show...ries-in-series

ok ya thats exactly what im asking and thats what i was hoping was the case so thanks for the info

A very common misconception about electrical systems is that current is pushed into the motor. It is not. The motor pulls what it needs.

Think of the battery as a fuel tank. You wouldn't worry about blowing up an engine just because you put a bigger fuel tank on it would you? The only difference is that it could run longer. With some exceptions (discussed below) the situation with electrical power systems in RC cars and planes is the same. More battery capacity and multiple batteries run in parallel don't change what happens to the motor because it will only draw the amps it needs to run the speed that the voltage it sees dictates that it should.

However, in the real world changes to any component can have unintended effects on other components. Your motor will run the speed that the actual voltage it sees says it must run. Unloaded, that is simple enough. If the motor sees 8 volts and runs 1000 rpm per volt (known as the Kv rating) it will go 8000 rpm and draw as much current as needed to do so. When a motor is under load, it will pull more amps to keep the speed up. But because more amps are being pulled from the battery, the voltage will drop due to resistance. This resistance comes from every item in the electrical system and can make a significant impact. So maybe the motor under load only sees 7 volts and turns 7000 rpm. You can see this easily enough when you put a bigger prop on and can hear that the motor has slowed down a little.

So here is where things can get a bit tricky. If you buy better batteries, use bigger wire or better connectors, use multiple batteries in parallel or increase the battery capacity, you will reduce the resistance in the system. So the voltage under load will go up, speed will increase, and the amp draw will increase. And going to bigger batteries also adds weight, which then increases load and therefore amp draw. RC modelers usually allow a 20% or so margin of safety in our electrical systems so that those factors won't matter. But if you are running your power system right on the edge of what it can handle and then make a battery change, that can make the difference between survival and not.