Blew up my new motor - What to do now?

[chongo49]

To make a long story short. I bought a used 2013 Ezgo 48V S6 last Dec. Cart already had a 400 amp Solenoid, 600 amp Navitas controller, Plum Quick Bandit motor. My wife burned up the PQ motor in May. Got a new motor from Advanced Lift Motors, their Copperhead motor in June. They were recommended to me by the shop doing the repair. At the time I did all new Trojan batteries, and a different 400 amp solenoid.

Prior to the PQ motor burning up, the cart would do 27mph with lots of torque. After the new motor, cart would only do 21mph and felt like it fell on it's face once it topped out.

Shop said it's the controller, they can't program it for the new motor. I contact Navitas, the agree to upgrade controller to their 3.0 technology (Bluetooth). I got the controller back yesterday. Installed and drove cart, they said they would give a best guess to programming it and it went 24mph but lacked the torque it had previously.

I spoke with Stu from Advanced Lift Motors today to discuss the programming and since he wasn't familiar with Navitas he gave me an RPM limit (6800) to work with.

Tonight I started at 6400 and slowly worked my way up to 6800 RPM. Stopping periodically to physically check the motor temp. The Navitas APP never showed the cart getting too hot. On my way home the cart started to slow down quite a bit, once I noticed it, the rear end locked up. I skidded to a stop with smoke coming from motor.

Inspection of the motor it looks like a grenade went off.

I don't want to point fingers or play the blame game as ultimately, the blame lies with me as I tinkered with the settings when I really don't fully understand them.

That leaves me with a golf cart sitting in my driveway after pushing it 400 yards with the rear jacked up on a floor jack. Cannot get it into the garage. I need to do something quick.

I've emailed Scotty with Carts Unlimited and I'm waiting on his response but wanted to get as much input as I can. I'm more than 2k into this cart in the past few months and sick to my stomach at this point. I know the S6 motor is larger than the S4, making it more difficult to track down.

What would be the recommended controller/motor combo? I want reliability. Performance is a distant second at this point.

Cart has 4" lift, 24" tires, carries my family of 8 around the neighborhood. Pretty much flat roads

Thanks in advance.

[BobBoyce]

So you took an already overloaded platform, stressed it even further with way oversized tires and an overpowered controller. Then tweaked the motor RPM beyond its rating until it grenaded. Replaced it with a lower powered motor that is refusing to be abused, and asking us to help you push it until it grenades? Does that pretty much sum up the question?

Just because it has more seats does not mean that the driveline is up to the task of moving that many people (weight) at a speed way above its design limits. For what you are trying to do with it, you're going to really want a 72V AC drive system and a much higher kW AC drive transaxle. And if you insist on really large tires, you're going to need to change the gears in the rear axle to allow the motor to operate within its design limits. Whoever built that S6 that you bought did not set it up with your usage in mind.

[Golf cart guy]

Field mapping was way off and burned the motor up. You can make them go fast, but there has to be a balance, otherwise disaster happens

[chongo49]

Originally Posted by BobBoyce

So you took an already overloaded platform, stressed it even further with way oversized tires and an overpowered controller. Then tweaked the motor RPM beyond its rating until it grenaded. Replaced it with a lower powered motor that is refusing to be abused, and asking us to help you push it until it grenades? Does that pretty much sum up the question?

Just because it has more seats does not mean that the driveline is up to the task of moving that many people (weight) at a speed way above its design limits. For what you are trying to do with it, you're going to really want a 72V AC drive system and a much higher kW AC drive transaxle. And if you insist on really large tires, you're going to need to change the gears in the rear axle to allow the motor to operate within its design limits. Whoever built that S6 that you bought did not set it up with your usage in mind.

No. Not exactly. When I bought the cart, it was already setup. I added a lift and wheels/tires. Considering it's the same lift/wheel tires you can buy on brand new S6's I wouldn't think it would be too taxing on the cart itself. Nothing in the controller was messed with, on my part with the PQ motor.

As far is weight is concerned - its two adults and 6 kids under 9 (of which are under two), about the weight of 2 more adults. The new motor was purchased based on the recommendation of the shop handling the repair. The change to the RPM limit was based on the advice of the builder who stated the motor could handle those RPM's. Nothing else was changed.

At this point, I'm just looking for a recommendation for a motor/controller combo that works well together, and will get the cart around the neighborhood.

[scottyb]

This cart is a bad design as it sits. There are too many mechanical factors against the drive train for success.
This cart will not be reliable until the load is reduced with significantly smaller tires and/or a change to lower gearing.

[kernal]

Originally Posted by chongo49

No. Not exactly. When I bought the cart, it was already setup. I added a lift and wheels/tires. Considering it's the same lift/wheel tires you can buy on brand new S6's I wouldn't think it would be too taxing on the cart itself. Nothing in the controller was messed with, on my part with the PQ motor.

As far is weight is concerned - its two adults and 6 kids under 9 (of which are under two), about the weight of 2 more adults. The new motor was purchased based on the recommendation of the shop handling the repair. The change to the RPM limit was based on the advice of the builder who stated the motor could handle those RPM's. Nothing else was changed.

At this point, I'm just looking for a recommendation for a motor/controller combo that works well together, and will get the cart around the neighborhood.

Brand new S6s and L6s are 72v AC.

[chongo49]

Cart does have 14:1 gearing.

[kgsc]

Just as an option. A few years ago I built a 6 passenger shuttle with the big wheels and tires and the like. Just like you it cooked the motor. Ended up ordering a motor from EMP that was built more for what the cart would be doing. Bigger case and wound to spin slower. I also had them install a thermal cutout that if the motor got too warm it would close a switch. I wired that into the activation circuit such that if it got warm it would shut down the cart. Your issue sounds like a field map problem or was.

[bronsonj]

Sorry to hear about your woes. 6800 RPM is pretty high. If it looks like a grenade went off in the motor and you didn't exceed 6800 rpm and that was the motor manufacturers recommendation, I would contact the motor manufacturer and see about a replacement under warranty.

Generally, for most golf cart motors, people on this forum say to stay to 6,000 or less.

[BobBoyce]

Originally Posted by kernal

Brand new S6s and L6s are 72v AC.

That was why I mentioned 72V AC Drive. That is what E-Z-GO had to go to in order to make them survive long term. Trying to do that with an older 48V S6 or L6, just because newer ones can do it, is building for failure. My EV design experience tells me that until the drive system can keep up with the expected performance demanded, there will be nothing but back to back failures with what is being attempted.