89 EZGO Marathon Electric Poor Power

[KeystonePig]

I am doing a restore on the above cart. It's 36v electric. Has good torque on the start and on flat but speed isn't great (haven't checked actual mph yet). Going up slight grade with one child in front speed goes down to the point that I'm feel like the flint stones and M ready to use my feet. As far as I can tell everything mechanical is all stock and more than likely original.

I replaced all the battery wires with 4ga wire and due to having a buddy who services electric vehicles, I have 4 of the 6 batteries that are less than 3 years old. He is getting me 2 more this weekend. Power improved slightly with replacing 4 of the batteries but still seems like a dog to me.

I put a 5" lift and bought 12" wheels with 23" tires that I am going to put on. Also going to put a rear seat on for the 2 kids.

Will use it for campgrounds mostly, no off roading at all. I am totally not mechanical other than basic stuff so please respond in "Golf Carts For Dummies" language. Lmao. So please help me get this thing to where I want it to be without breaking my bank.

Thanks in advance.

[Filthy-Beast]

Sounds like a weak battery pack. Test voltages under load. bigger tires will lower torque, so get some new shoes.

Sounds like you'll need new batteries and higher amp controller. might want to look into changing to 48v since you'll need to replace batteries and all the same components to go to higher amps

[KeystonePig]

I ordered a volt meter that will tell me the volts under load. 4/6 batteries are less than 3 years old. Could they be shot already? I'm getting 2 more this weekend. I see you have a 500a controller on your 36v. Would that work? Thanks for responding.

[Filthy-Beast]

If the batteries aren't balanced. Like adding two new batteries to a pack of 4 old marginal batteries, you'll kill the new batteries much faster than if they were all new. Also if you have a 12v load wired directly to two batteries instead of using DC-DC converter. the imbalance in charge state will impact life.

Yes a 500amp controller will get you more torque to handle bigger tires and rear seat, but you need to replace all high amp components. Controller, solenoid, cables, F/R switch.

So if you need new batteries and are replacing all the high amp components you might as well go to 48v with 6 8V batteries.

My cart came with the upgraded controller, solenoid, F/R switch and cables with good 6v batteries. When it's time to put in new batteries I will be upgrading to 8V.

[KeystonePig]

I am trying to avoid replacing batteries at this point. Was going to upgrade the controller and such first. My wife will kill me if I dish out another $1200 for batteries right now. Thanks.

[scottyb]

23s 23 inch tires reduce torque by 28% over stock 18 inch tires.

1989 marathon may be a resistor coil cart. See pics
If it is the cart will need a lot of upgrades to roll the 23s and a load up any hills.

Pic #1 resistor coil drive
Pic #2 solid state

[KeystonePig]

Mine is not resistor. It has a controller. Mine is pic #2.

[Filthy-Beast]

Before you put the lift and tires on or buy a new controller get the volt meter installed. Then check voltage 12 hours after a full charge and under load going up a hill. The bigger tires will make your problem worse. If you have weak batteries under load a high amp controller won't help for long.


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[Helirich]

Batteries that are "less than three years old" could be very good or junk. I'm courious why your friend can get them if they are good. I suspect that they were lacking and someone who doesn't care about the cost said "fix it".

Now that doesn't mean their shot, but your not just wanting a usable cart, you want a super cart. I'm not putting you down for that (I'm in the same club), but I had to spend the cash.

I would get the batteries and install the wheels/tires. (The price is right) then see what you have. Im guessing your going to have to spend cash also.

[KeystonePig]

Thanks all.