'84 electric Marathon rebuild question

[rlw]

I just picked up an '84 Marathon for $290. It's going to be a winter project. Amazingly, the thing runs, but not very well. I've been lurking on this forum for a couple of weeks, and it's been a treat reading the rebuild threads.

The battery trays are shot, and the guy who sold it to me stuck a couple of 2x8's under the batteries to keep 'em from dragging on the ground. There's quite a bit of flaky rust on the frame where what's left of the battery trays are connected to the frame. The body's beat up, but generally in good shape - not alot of rust there, just banged up. There's a hole where battery acid ate through the driver side corner of the cover under the seat, probably repairable with fiberglass or Bondo.

There are 3 different kinds of batteries - 3 Trojans, 2 Crowns, and 1 is some other kind (don't recall, I'm already on my second Black Velvet and sody water as I type this ;^). After a full charge, the Trojans read about 6.3 volts, the Crowns aren't so good, and the (can't remember) battery is about the same as the Crowns. We took it for a ride today over to our neighbor's place - about 25 minutes drive time total - and it was pretty close to dead when we got back. There's a fairly steep but short grade between my place and his - my Marathon crawled up that hill, but made it. My neighbor followed me back just to make sure we made it.

My neighbor has a '98 electric TXT with either a PDS or DCS controller (never took to cover off to find out) - we've been driving that around his 55 acres and my 6 acres for about 5 years now. He charges it up every 3-4 days, and they use it daily on the farm.

I've got another neighbor who builds and races stock cars (he's a MOPAR fanboy). He's got a complete shop in a heated 120x60 pole barn, with a lift, paint room, and just about every tool known to mankind. I'm gonna tempt him with 30-packs of Nattie-lite as rent for a space to work in. I also think he'll jump at the opportunity to work on a golf cart rebuild.

I've read (on this forum) about folks who've rebuilt a Marathon from the frame up, and most of 'em have replaced the resistor-based controller with one of the solid-state controllers (ATX - I think). I've also read about others who've upgraded a TXT/DCS or PDS with a similar controller. Those look like a great way to go, but the cost of those controllers is out of my range.

At a minimum, I plan to tear down the cart, clean off the rust, get my neighbor to weld some support steel to the frame, and paint the frame. I'm also going to ask him to help/show me with/how to straighten out the cowling and repainting that.

I could just clean up and put back the resistor controller, but it occurred to me that with all of the rebuilds on this forum, there may be some TXT/DCS/PDS controllers out there floating around that I could get.

Here's my question (FINALLY!):

Is it possible to replace a resistor controller with a TXT controller and keep the stock Marathon DC motor? From perusing this forum I think the Marathon's motor is a "series" motor. Am I wrong?

I realize I'd have to also install a potentiometer-based accelerator to replace the wiper board.

Are these (used) TXT controllers significantly cheaper than the ATX controllers?

Am I barking up the wrong tree?

Any suggestions or replies will be greatly appreciated.

This forum is a great resource on carts - I'm glad I found it.

Thanks in advance,

RLW

[madoc1]

sounds like a plan. your original motor will work, and as you said, you will have to rig up a pot box. roady now has a whole conversion kit for this. you can post a wt buy in the for sale forum for the controller and solenoid. new cables , at least 4ga. should be done also.

welcome to BGW.

[rlw]

Jim,

Which controller and pot box do I need? I think the batteries already have 4 gauge wiring (have to check that out later today) - there isn't much corrosion on the lugs, but the guy I bought it from could have cleaned that up before I got there.

Thanks for the welcome.

RLW

[madoc1]

don't know the # on the controller, but it will have to be one that is compatible with the potentiometer. someone with more knowledge will have to help you there. read up on it in scottsb's web sight. at cartsunlimited. a sponsor. or send him a message or call.

[scottyb]

You may be backing up the wrong tree depending upon your level of skills and equipment available.
The controllers input needs to be compatible with the throttle position indicating device output.
Marathons used a 0-5k potentiometer
Later TXT used a induction throttle system (ITS)
The AXE alltrax was programmable for either.
Look in the sale section.
Hope this helps.

[rlw]

Originally Posted by scottyb

You may be backing up the wrong tree depending upon your level of skills and equipment available.
The controllers input needs to be compatible with the throttle position indicating device output.
Marathons used a 0-5k potentiometer
Later TXT used a induction throttle system (ITS)
The AXE alltrax was programmable for either.
Look in the sale section.
Hope this helps.

@scottyb, @madoc,

Thanks for the responses. I'm new to rebuilding electric carts, but not new to things electro-mechanical. My '84 Marathon has a wiper switch/resistor "controller", not a potentiometer (unless you count picking off different connections to a "heating element" as a potentiometer! ).

I'm aware I'd need to replace the throttle, or rig up some kind of linkage from the arm that drives the wiper (after removing the wiper) to a 1-5k ohm pot or the induction throttle (if that's what the controller I get requires). I've got a friend with a commercial CNC machine shop, so any of that kind of linkage fabbing should be in his wheelhouse.

Maybe I've asked the wrong question(s). Here's a new stab at it:

Has anyone replaced the wiper switch/resistor controller assembly with a stock TXT controller and accelerator (throttle) assembly on a Marathon the same vintage as mine?

If so, which TXT controller/throttle combo works best, keeping the original, stock Marathon motor? What kind of issues did they run into?

My understanding so far: The motor in my '84 Marathon is a "series" motor. The later electric TXT models have three kinds of drives: "Normal", DCS (Drive Control System), and PDS (Precision Drive System). The "Normal" controller will control a series motor. I'm not clear if a DCS controller will, and I believe I'm correct when I say the PDS controller WON'T work with my motor. If I remember what I read correctly, the motor in a PDS cart also works as a generator/governor, has different windings than a series motor, and along with the controller, provides some kind of regenerative braking on downhill slopes, in addition to acting as a governor to limit the top end speed.

I'm cheap, and the fancier controllers are out of my price range. I was hoping to find someone who upgraded from the stock TXT setup to one of those "fancy" controllers, and would be willing to sell the stock stuff. I dug around in the "for sale" section, and saw that there have been quite a few for sale. Also, there's a local (couple of miles away) EZGO dealer, and I thought THEY may have some old controllers laying around for sale.

From reading various posts in these forums, the resistor control on my Marathon is very inefficient - even if you only have the throttle down 1/4 of the way, you're still using full power from the batteries, since the current NOT being used by the motor is burnt off as waste heat by the resistor.

Electronic controllers are "choppers", working not unlike an incandescent light dimmer - varying the duty cycle of the pulse to limit current to the motor. These are inherently more efficient, as they only send the amount of power (over time) the motor needs to propel the cart at that speed. Hence, the cart runs longer on a full charge with a solid state controller than with a resistor controller.

So, my assumption is that my cart will run better (especially up hills) if I replace the old stuff with something a bit newer. If I can find a used TXT controller/throttle combo, it will at least be better than the current setup, even if it's not as good as the "supercalifragilisticexpialidocious" setup. The time to do this work is while I've got the whole cart torn down to replace the battery trays and weld some plate onto the frame where it has rusted.

I admit I'm a newbie to carts, and could very well be missing something. Please correct me if my assumptions are wrong.

This is a great resource, and I really appreciate having access to the collective expertise in these forums. Sorry if I'm too long-winded.

Thanks,

RLW

[JohnnieB]

HI rlw, Welcome to BGW.

The nomenclature and terminology of carts is confusing at first, but the fog lifts after a while.

Marathon, Medalist, TXT, RXV, ST, MPT and Workhorse are the various E-Z-GO Models (Body styles). Some models came in more than one configuration.

Examples:
There were two types of Marathon model.
Resistor or Electronic contrtoller.
Both had a Series motor.

The TXT model had two different type motors.
Series (Series wound motor - meaning same current flows through armature flows through the stator)
Sepex (aka Separately Excited or Parallel wound)
Depending on the year, but there was some overlap, the Sepex TXTs were either a DCS or a PDS.

If the year & model and type drive are posted when asking question, better answers are usually received because there are so many variations and not everything applies to all variations.
(IE: A 2000 TXT could have a Series or a Sepex motor and if it had the Sepex, it could have a DCS or a PDS controller.)

Here's a website where you can plug in your serial number and get a description of your cart as it was built. (Maybe - some of the older info is missing)
More importantly, you can scroll down to bottom of page and see all the different E-Z-GO models and the years the were built.
http://www.shopezgo.com/customer-ser...ialNumber.html

You've probably got a "1984 Marathon Resistor" cart, which has a Series motor, so neither DCS nor PDS controllers will work in it since they are made for Sepex motors.

Unfortunately, I know much next to nothing about Marathons in general and even less about converting a resistor cart to a controller cart, so I can't help you much in that area, but I understand it can and has been done by some of the people here.

[rlw]

JohnnieB,

Thanks for the reply and the great explanation. You're right about the nomenclature and terminology - I'm starting to see through the fog.

I definitely have a resistor cart. I can see the "electric dryer heating element", ummmm, resistor, between the rear wheels. I've also got the perpendicular-to-the-axle motor.

Looks like if I want to do a resistor to controller conversion on the (relatively) cheap, I'll need to find someone who upgraded a series TXT cart (non-PDS AND non-DCS) and had a "normal" controller for sale. I'll also need to find out what kind of throttle that controller wants to see - inductive or potentiometer.

I see by your sig you're from West-By-God-Virginia. I'm a born'n'raised Fairmonter, living temporarily in Ohio for the past 35 years.

I've seen your replies in quite a few posts. What the heck is the photo in your avatar?

Thanks again for the reply,

RLW

[JohnnieB]

Originally Posted by rlw

1. Looks like if I want to do a resistor to controller conversion on the (relatively) cheap, I'll need to find someone who upgraded a series TXT cart (non-PDS AND non-DCS) and had a "normal" controller for sale. I'll also need to find out what kind of throttle that controller wants to see - inductive or potentiometer.

2. I see by your sig you're from West-By-God-Virginia. I'm a born'n'raised Fairmonter, living temporarily in Ohio for the past 35 years.

3. I've seen your replies in quite a few posts. What the heck is the photo in your avatar?

1. There were Marathons that rolled out of the factory with controllers and they had Pot Box type throttles, so the mechanical components connecting the pedal to the potentiometer do exist, but if I couldn't lay my hands on one, I'd go with an ITS since only wires have to be ran from under the floorboard to under the seat instead of a plumber's nightmare of rods, shafts and levers. Of course, a little WV Engineering might solve those problems too.

2. I was born in TN, retired in WV and hung my hat in several places in between. If I were a few years younger and with a good tailwind, I could throw a rock and hit OH, which is a local pastime in Point Pleasant.

3. It's the Wullenweber (circularly disposed antenna array aka Elephant Cage) part of the AN/FLR-9V that used to be at RAF Chicksands, UK. To give you a size perspective, the visible array alone covered 37 acres. I didn't work on the physical antennae, instead I babysat a couple million transistors, a few ICs and Tubes in the round building in the middle and the OPS building about a mile away. (Yes, I can read a schematic )

[madoc1]

johnie, i was ctm and worked at a ww site in winter harbor, me. in 68. b-4 that was in cuba.