Ezgo Marathon 36 to 48 volt conversation

[Crawler487]

I have a 93 ezgo marathon and it has a 400 amp controller meant for 36 volts or 48 volts (right now it runs on 36 volts) also it has the plum quick bandit upgraded motor my question is, can I just swap over to a 48 volt solenoid and add two 6 volt batteries and be done? Or are there other things I'd have to change out too?

[JohnnieB]

What make and model controller? If it is an Alltrax AXE, it is user programmable and you may have to change some of the settings.

What solenoid is installed? Some, but not many, work at 36V, 42V and 48V.

The Pre-charge resistor across the solenoid contacts needs to be changed from 250 Ohms to 470 Ohms.

Of course, a 48V battery charger will be needed.

Also, the two batteries added should be the same AH and about the same age as the existing six.
If new batteries are used, they are sacrificial batteries. In other words when you have to buy new batteries, you will have to buy eight new ones because the two added ones will quickly acquire the aging of the existing batteries.

[Crawler487]

It is an after market curtis I believe id have to check but its not an alltrax and I would be replacing the solenoid with a 48 bolt one because I have a few and I have a car charger that charges up to 48 volts so besides the two batteries I'd need, will I be fine? Will the throttle assembly and everything be fine with 48 volts?

[JohnnieB]

The pot-box throttle will be fine. The controller supplies the voltage to it and if the controller is set up to work on 48v, it should supply the right voltage to it.

The 250 Ohm pre-charge resistor may get mighty hot if you don't change it to 470 Ohms, but other than that, you plan sounds okay.

[Crawler487]

Ok cool thank you very much I will buy a new resistor for it before I start this project

[yurtle]

Will a car charger work on deep cycle batteries? Is it automatic or just a timer type charger?

[Olman]

One thing I didn't think about when I upgraded to 48 volts was motor rpm. As an afterthought I asked my motor manufacturer about it (they built the motor for me when I had stock controller and 36 volts) and they said I was limited to 30 MPH. They also said to NEVER run full throttle with the wheels off the ground. They said they could rework the motor to take the higher rpm but I will just be careful with the speed and leave it like it is for now.

Edit: My pucker factor limits me to under 30 mph anyway.

[JohnnieB]

Originally Posted by Olman

One thing I didn't think about when I upgraded to 48 volts was motor rpm. As an afterthought I asked my motor manufacturer about it (they built the motor for me when I had stock controller and 36 volts) and they said I was limited to 30 MPH. They also said to NEVER run full throttle with the wheels off the ground. They said they could rework the motor to take the higher rpm but I will just be careful with the speed and leave it like it is for now.

Edit: My pucker factor limits me to under 30 mph anyway.

Did they mention a max RPM to stay under?

With 20" tires and 12.44 gears, your motor is spinning at approximately 6,300 RPM at 30 MPH.
However, the size printed on the sidewall of a tire is very iffy and the actual high might be an inch or more in either direction, so if you can tell me the exact height or your tires (or circumference), I can tell you your motor RPM vs MPH much more accurately.

D&D recommends I not to exceed 6,500 RPM with my motor, which just happens to coincide with the max RPM I get at 42V, so I'll probably not go to 48V. But if I did, I could back off on top speed by reprogramming the controller

I exploded a stock PDS motor at about 7,600 RPM, but there were more factors involved than just how fast it was spinning when the armature decided to grow and become one with the field windings.

[Sir Nuke]

yeah Johnnie....its always a bad thing when you have an unexpected "Energetic Disassembly".

[Olman]

Johnnie--They didn't give me an rpm. I guess I could ask them however. I told them I had 20 inch tires though. I just measured my tires (diameter front to back with tire pressure at 22 psi) at 21 inches exactly. No wonder I lost so much torque when I first put them on. I thought they were 20 inch as advertised. Since the tires are 21s, maybe I'm safe at 30mph.

I can't reprogram but I can back off the skinny pedal.