1990 EZGO Marathon? Need help upgrading!!

[tuckercart]

Hello All,
I am brand new to all of the golf cart stuff, the rabbit holes are endless!!!
I was given an old EZGO-- Serial: 606022 Model: H2790
All i know is its 1990, from the model number. I'm assuming it's a Marathon based on cruising through the forums.
I'm using it in a trailer park just east of Toronto, Ontario. A mix of flats and hills.
Just replaced all the batteries, 36v. It runs ok, slow and even slower on hills.
I want to upgrade the whole cart but want to start with the drivetrain.
I've read about series/pds/dcs and am lost already to what this cart has/is.
Attached are pics pre new batteries. Soooo new motor/controller/solenoid?
And can i just add 2x more batteries for 48v?

Thanks for all your input in advance!!

[bronsonj]

That is a series cart.

Going uphill it will always slow compared to running on flat ground. But going higher V will give you better speed and torque.

Before going with more voltage you'll want to check out that controller. It is sitting in the middle of the batteries. There is a chance it is compatible with 36 and 48v. If it is, you got lucky and can save $$$.

Before we get to all the details on upgrading, what is it you want the cart to do? Lift with huge wheels or stock height and stock wheels? Mountain climbing? 2 people or 4? Pull a utility trailer? Off roading? 15mph, 30mph? People here use their carts for all sorts of things and what you want will direct what upgrades you need to accomplish it.

How slow does it go now? 12 to 13mph?

This option isn't for people who don't plan to upgrade anyway... But if it were me and my free cart I would likely try adding one more 6V battery and set of cables (use welding cable not auto parts store car battery cables) and see if the controller is OK or if 42V lets all the magic smoke out. Full well accepting that if it does I would need to spend $$$$ and upgrade to 48v. If the controller doesn't fail, I'd drive it and see if I liked it. The stock charger can still charge the 6 batteries and the 7th you'd have to charge with a 6v charger temporarily. Just make sure you wire the chargers so one 'sees' 6 batteries and the other sees just the 7th one.

It is possible it will be fine and it is possible it will quickly fail.

If it is fine, run it and see if you like it. If you like it then you'll need a 42V charger and you're done. Unless you want big tires/lift/4 passengers/higher speed, etc.

If you don't like it or the controller lets out all the magic smoke, then you'll need a controller, another battery, a charger, a solenoid and the other battery cables. Depending on how fast or how crazy you want to go you there are a few different options, 300 amp, 400 amp, 500 amp, possibly a new motor, etc. But it depends on your final vision for what you want to do with the cart.

Just because I'd do it doesn't make it right, but at the moment you sound ready to spend $ anyway for a 48v upgrade and you've only got money in the batteries so far... My buddies cart had a 36 to 48v compatible controller in it when he got it. I hear that's not common, but I've seen it myself.

Also, grease the fittings on the front end. It's likely the front end of that 30 year old cart has never been greased. It will dramatically improve your steering if it really needs the grease.

$0.02

[tuckercart]

Awesome response BronsonJ,
I will eventually want to lift and put bigger tires on it and want a lot more speed. So as I build it out i want to future proof it. I will be carrying 2-4 people at any given time, mostly pavement and no off roading. Flat with a couple of hills.
I will check the controller this weekend. The roof also fell apart during transport so I will figuring out where to get another one.

Tuckercart

[bronsonj]

What'd the controller indicate? Did you find a data plate on it and google search it or does it say right on the controller what it's compatible with? My buddy's Taylor Dunn had stamped right on the controller 36 - 48v.

The biggest unknown is how much more speed you want. You can do a 4" lift with 22" or 23" tires. (Make sure you get high pressure tires! Tires under 13 psi will kill your speed! Those low pressure tires are for lawn mowers and ATVs, not golf carts...) The bigger the tire the more torque you will lose but you will gain both torque and speed from going 48v, so the torque differences will likely offset each other so you'll have the same accel but with higher top speed.

If you're looking for 20+ that's pretty easy for most any 48v cart with an aftermarket controller. 30+ is also doable, possibly while still on the stock motor. But you don't want to spin the stock motor past 6,000 rpm or it can come undone. On my cart with 23" tires and an rpm limit of 5600 I can get to 30 and it is really not fun that fast. I have a 6" lift as well, so a 4" lift would help make it more comfortable as would slightly smaller tires. There are people on this forum that have 40+ mph carts... But that's a bigger build with more mods to make it handle and brake from those speeds. Heck, downhill braking from 15mph makes me wish I had front brakes...

Just throwing out ideas, but I've a couple real nice topless carts. There's one that used to be in my hood that had a little sporty half windshield in the front. Here's a different cart with a bimini top and shorty windshield that's similar to the one that was in my hood.
https://www.frugaldougalsgolf.com/fi...ded/Utland.jpg