marathon will not climb any incline

[solarboyz]

Marathon will operate fine on level ground but will not climb a hill.swapped out motor, (had a spare) installed batteries ( which held at 38.5 for 48 hours in the garage). Still will not go up hill. Battery voltage only dropped to 37.6 while in motion and held there for 500 yards. Then I came to a dead stop at bottom of fairly modest grade-15%. took off , got maybe 5 yards. Batteries held at 37v even with vehicle stopped on the 15% grade and pedal floored.
Ready to upgrade, but want to have more certainty on which parts will solve this first.

[cgtech]

Bad controller is my guess (same thing happened to me). But, test throttle sensor with wires disconnected from controller (0-5000 ohm from controller wires 2&3, white & black wires).Given 3 blocks, it would go alright, but would not go over a 1" incline to cross a sidewalk from zero speed. I killed my controller by putting 48v to it (had a spare alltrax controller, wanted to see just what the stock controller was capable of, 48v for about a month was my answer). The battery voltage staying solid tells me the controller is not passing the power to the motor. Get a SPM400, if you plan on keeping stock motor. BTW- stock motor is totally fine on 48v.

[solarboyz]

The Ohm's law thing is very funny. I will pass the test, though there may be smoke!
Scotty B recommended a package that lets me switch to 48v later, right now I want to get it running. I will try ( and pass) your test suggestion first. Thanks!

[scottyb]

It's hard to get a good recommendation without all the information. There are several factors that determine what size control is best. 400a tends to disappoint serious off roaders or carters in steep terrain. Where the loads are big 500a is a better choice. If an aftermarket motor is in your future 500a is a must in my opinion 400 will limit performance and future choices.

[cgtech]

If ya gotta smoke, please, do it outside.. Dont wanna light the place on fire.