EZGO was a NOGO

[ekgguy]

It has been a while since I had to come one and ask a question. Since the completion of my cart for the High School Band it has been a pretty stalwart little cart.

It is as it appears in my signature, an 89 Marathon with all the original electronic interior witht he exception of 2ga wires.

Anyway, we have used it for the last couple of years with no issues until last monday. We took it to the school districts Christmas Parade. We have done this for the last couple of years with no issues. This time we got about halfway through the parade (lots of starting and stopping and slow moving (partial pedal)) and the cart started to give out. Had the pedal all the way to the floor and we were barely moving. So we parked it and walked the rest of the way with the band. When I went back to get it, it worked just fine, and I have been tooling around the neighborhood with no issues.

Like I said, it is all original electronics right down to the resistor and has been a good little cart.

I am guessing, that the resistor got to hot and started cutting out instead of adding more power to the motor. Once it cooled down, it works just fine, and I have not loaded it again like I did that night.

The batteries are about 4 years old, but they have been maintained and run through a regular charge / discharge cycle and i have right at 36 volts from the pack so we are good there.

What I am looking for is a concensus.

Is a cart this old worth gutting all the electronics and updating everything or should we start looking for a newer model? Like I said before, the outside has been completely redone like you see in the pictures of the build, so cosmetically it is in good shape.

Thanks all......

[scottyb]

Lots of people who have built as nice a Marathon as you have (I scanned the build thread) have come to the same crossroads as you.
You now have a cart that looks like you want and functions as you designed but doesn't run as needed. The culprit is the 50 yr old electronic engineering. Not that the cart is 50 but the electronics it runs on are than and more and still in use in your toaster oven.
Anyway, lots of guys have opted to convert these builds to modern electronics. I have made a bolt in plug and play kit you can install in a weekend easy.
Read this page http://cartsunlimited.net/Scottyb_s_Conversion_Kit.html and email me scottyb@cartsunlimited.net

[ekgguy]

Thanks Scotty. The last time that i even thought about this you were just putting the kit together and it was still in the testing phase. I will look through your thread in the am.
Thanks for chiming in early.

[JohnnieB]

Originally Posted by ekgguy

The batteries are about 4 years old, but they have been maintained and run through a regular charge / discharge cycle and i have right at 36 volts from the pack so we are good there.

FWIW:
At 36V, the battery pack's State of Charge is less than 50%. (See attached SoC vs Voltage chart)
Either the battery pack is sick, the voltmeter used is sick, or the charger is sick, or the voltage stated is inaccurate.

A fully charged 36V battery pack should read 38.2V after they have rested 12 hours.

[Dela]

Originally Posted by scottyb

Lots of people who have built as nice a Marathon as you have (I scanned the build thread) have come to the same crossroads as you.
You now have a cart that looks like you want and functions as you designed but doesn't run as needed. The culprit is the 50 yr old electronic engineering. Not that the cart is 50 but the electronics it runs on are than and more and still in use in your toaster oven.
Anyway, lots of guys have opted to convert these builds to modern electronics. I have made a bolt in plug and play kit you can install in a weekend easy.
Read this page http://cartsunlimited.net/Scottyb_s_Conversion_Kit.html and email me scottyb@cartsunlimited.net

Scotty I have a neighbor with a resistor cart who would be interested in your kit, any pics I can share with him? Saw the site but couldn't see what exactly it looks like.

Thanks

[scottyb]

Originally Posted by Dela

Scotty I have a neighbor with a resistor cart who would be interested in your kit, any pics I can share with him? Saw the site but couldn't see what exactly it looks like.

Thanks

Ask your neighbor to email me

[ekgguy]

Originally Posted by JohnnieB

FWIW:
At 36V, the battery pack's State of Charge is less than 50%. or the voltage stated is inaccurate.
A fully charged 36V battery pack should read 38.2V after they have rested 12 hours.

Jonnie, it is probably the latter as i cannot remember exactly what the number was, but it seemed ok. I have let the pack charge all day until the charger shut off and at the 12 hour mark, I will go test the voltage. Just so we are on the same page, where is the best place to measure from. I want to make sure we are comparing apples to apples here.

Matt

[JohnnieB]

Originally Posted by ekgguy

Jonnie, it is probably the latter as i cannot remember exactly what the number was, but it seemed ok. I have let the pack charge all day until the charger shut off and at the 12 hour mark, I will go test the voltage. Just so we are on the same page, where is the best place to measure from. I want to make sure we are comparing apples to apples here.

Matt

According to the schematics I've got, the battery packs in Marathon resistor carts were wired two different ways.

With either, if you follow the wires from the cart's charge receptacle to the pack, they will (should at least) connect to the Main Positive and Main Negative battery terminals. Measure the pack voltage between those two terminals.