Considering off-lease 2018 RXV - What parts to replace?

[BobBoyce]

Originally Posted by Chevota Guy

I'll continue to follow this thread with interest. I have an aging 2010 Danaher controller and the options appear to be:

1. Navitas TAC2 direct drop in replacement. Easy for a layman like me.

2. Upgrade to a "tuned" Curtis controller with either a harness replacement or harness modification.

The Curtis has proven the test of time and reliability. The Navitas is the new guy in the neighborhood so the pros and cons are truly confusing.

I like the idea of simplicity and being able to "dial in on the fly" of some critical parameters on the Navitas, but I don't know about longevity and reliability. The Curtis has a long history of good things.

I currently have an aging 2010 Danaher that runs just fine and gives me 24.5 mph which is more than adequate for my needs, but I'm thinking my days may be limited and trying to figure out the next path.

I'm planning on coming out with a 2 mode OTF add-on for the RXVs.

[fstop]

Originally Posted by BobBoyce

Exactly, their spec is that the 3 phases are 200 Amps each which they add up to equal 600 Amps. An engineer should know, that is not the way to actually calculate delivered Amps. If Curtis were to use that method, their stock 235 Amps per phase controller would be rated for 705 Amps. They know to only count the current of one phase, since they are in balance... With 3 phase, there are factors that can result in unbalanced phases. Smoothest and most efficient operation occurs when the phases are adjusted to be exactly balanced. There are adjustments to do that in a Curtis controller.

I really like that they came out with an aftermarket 3 phase AC controller. That gives options, and it threatens Curtis with the knowledge that they are not the only option for affordable AC drives! I just wish that they had made it as adjustable as the Curtis, and were more honest with their rating. They are counting on the ignorance of prospective buyers to not know the complexities of calculating 3 phase AC Amps. To me, that is a bit dishonest. I figured if I pointed that out enough times, they would get the hint. Other than those points, I would be happy to promote them. I can understand why they would not allow the average user to not allow balancing of the phases, because users would royally stuff up their balance. But advanced programmers that know their stuff may need to be able to rebalance as a controller ages.

Bob, excuse my ignorance, but what is the reason for a wiring harness change etc... related to using the stock Curtis controllers? Is that only on older RXVs? Would I need any of that with a 2017-2018 factory cart?

I was under the impression there wouldn't be anything required other than reprogramming the controller - no hardware changes.

My Tac2 was a 10 minute plug and play (on my Onward, anyway).

[fstop]

Originally Posted by molfpedal

I just put my second Navitas Tac 2.0 in a 2011 RXV (the first one lasted 3 weeks) with a 14s 120aH leaf battery pack. The first one would go 32mph w/215-50x12 tires. That is as fast as it can be programmed with the RPM limit on the RXV and stock gears.
As for the rating, I haven’t seen any information that leads me to believe that it is only 200 amps as I saw it send 260 to my cart today with it set at 27mph.
Bob, where did you see this?

I assume you are using the Tac2 with the stock RXV motor? (not the 4kw or 5kw Navitas motors)

So you are hitting the RPM limit that the Navitas app will let you program into it? I'd use 22" tires, so speed might be a click higher - maybe 1mph or so in my case, but plenty high for what I need in this cart. In fact I'd probably limit it to 28 or 30 as this would be more of a general use cart. Would use larger tires on 12" rims for softer ride.

What is the RPM limit on the actual stock RXV motor? I've read that you don't want to over-RPM these things or bad things will happen...

[Chevota Guy]

Originally Posted by BobBoyce

I'm planning on coming out with a 2 mode OTF add-on for the RXVs.

I will be watching for that !! Good luck.

[cgtech]

Originally Posted by fstop

What is the RPM limit on the actual stock RXV motor? I've read that you don't want to over-RPM these things or bad things will happen...

I dont know where you read these things specifically about a RXV motor.

6,400 rpm is "Freedom speed", stock wheels 19mph.

9,600 rpm is my opinion of "higher end", 27mph on stock wheels.

12,something is the highest I've ever seen, no failure.

I have "helped out" many RXVs, and never once seen a physical failure of even one of those motors. I'm not counting speed sensors & temp sensors, I'm talking about the electromechanical hardware.

[fstop]

Originally Posted by cgtech

I dont know where you read these things specifically about a RXV motor.

6,400 rpm is "Freedom speed", stock wheels 19mph.

9,600 rpm is my opinion of "higher end", 27mph on stock wheels.

12,something is the highest I've ever seen, no failure.

I have "helped out" many RXVs, and never once seen a physical failure of even one of those motors. I'm not counting speed sensors & temp sensors, I'm talking about the electromechanical hardware.

Well I guess I'd say maybe you don't want to over RPM any motor - not singling out RXV motor here.

So 9500 rpm is a common max rpm without issue for that stock motor it sounds like. Good to know.

Thanks!

[cgtech]

Originally Posted by fstop

Well I guess I'd say maybe you don't want to over RPM any motor - not singling out RXV motor here.

So 9500 rpm is a common max rpm without issue for that stock motor it sounds like. Good to know.

Thanks!

The design of the AC cart motors are inherently more tolerant of rpm than their DC counterparts (many DC motors wont even do 9,600 once). AC motors dont have all the copper in the rotor that can "fling out" at high speed.

And I actually try to avoid 9600, and stay below. I aim for 25mph.

[BobBoyce]

Originally Posted by fstop

Bob, excuse my ignorance, but what is the reason for a wiring harness change etc... related to using the stock Curtis controllers? Is that only on older RXVs? Would I need any of that with a 2017-2018 factory cart?

I was under the impression there wouldn't be anything required other than reprogramming the controller - no hardware changes.

My Tac2 was a 10 minute plug and play (on my Onward, anyway).

The Danaher RXV controller has a 23 pin plug, while the Curtis RXV controller has a 35 pin plug. The Curtis tests and monitors a lot more cartside peripherals than the Danaher. There are some wires to cut and splice. It is a lot easier to just buy a new main harness, pretty much plug n play then.

2017/2018 are good to go.

[BobBoyce]

Originally Posted by cgtech

The design of the AC cart motors are inherently more tolerant of rpm than their DC counterparts (many DC motors wont even do 9,600 once). AC motors dont have all the copper in the rotor that can "fling out" at high speed.

And I actually try to avoid 9600, and stay below. I aim for 25mph.

They are tolerant, to a point. You are far enough west that you're not seeing the results of a guy south of here that is hacking the encoder feedback and exploding RXV motors. He's making it read 5800 RPM at 30+ MPH with stock gears and tires. Do the math (spinning at 11600 RPM when reading 5800 RPM) and you'll see why the rotor is failing. It does not take many weeks or months of that for the cast aluminum to come out of the rotor slots and get jammed between the rotor and the stator lams. The rear end locks up at high speed and not much control when that happens.

[molfpedal]

Originally Posted by fstop

I assume you are using the Tac2 with the stock RXV motor? (not the 4kw or 5kw Navitas motors)

So you are hitting the RPM limit that the Navitas app will let you program into it? I'd use 22" tires, so speed might be a click higher - maybe 1mph or so in my case, but plenty high for what I need in this cart. In fact I'd probably limit it to 28 or 30 as this would be more of a general use cart. Would use larger tires on 12" rims for softer ride.

What is the RPM limit on the actual stock RXV motor? I've read that you don't want to over-RPM these things or bad things will happen...

I can tell it whatever speed that I want. However, I agree with cgtech that 9500 rpm is the high end. I have 20.5” tires and don’t want to lift my cart. Here is a picture of what I would consider my maximums.


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