Navitas 600A RXV Solenoid Questions

[DB Cooper]

Against the norm on this forum, I made an impulse decision to buy a 600A Navitas TAC2, I installed it last Thursday. I'm a relatively new cart owner, I purchased a 2016 RXV on a 6" lift and with 23s (brand new batteries) and then found this forum and became hyper-phobic of the controller issues. While my end goal is to get a tuned 350A Curtis, I couldn't find one on sale or deal with the logistics of the tuning, so went ahead with the Navitas. I think I'm still long for a 350A tuned Curtis, but felt I could run this for a while and pickup a 350A on sale and get it tuned at some point by the legend.

Rewinding a few weeks, I burned my solenoid on a stock Freedom/Mode4 config climbing a large hill. More than likely a poor terminal contact on the Trombetta solenoid caused that, but I got a new solenoid under warranty and life was good. I took that opportunity to put 2AWG wires in from ACDC. Cart ran fine for two weeks, then I put the Navitas in...

Given the whole scientific convos about the Navitas not being a true 600A, I had no worries about my brand new Trombetta 48V solenoid. I found comments about how the 600A Navitas is weaker than a tuned 235A Curtis, so figured my solenoid would be fine. I ultimately didn't care if one was more powerful than the other, I just wanted a reliable/stable cart that could do 25+ on 23s and not leave me stranded.

Anyways, after 5 miles of driving on Thursday and early Friday, the Navitas produced a 2-8 error code which is a "welded solenoid" error. Let me say, I did not hot rod the cart, I didn't climb any hills. I played a bit around with regen (never over 50%) as the brake pedal mushiness was driving me nuts on the Navitas, and I did a run up to 32 mph on flat without aggressive acceleration on a flat road. The cart got home, and the error was produced on a later restart, the ride prior to the restart never topped 25 and was very relaxed.

One thing I'll say about Navitas, their support is great. Friday night, a tech called me and told me I likely had a soft weld on the solenoid and to tap it with a mallet to free the weld. He commented that it's an issue caused by regen on new and/or lithium batteries on undersized solenoids (I think he said also if the batteries were fully charged which mine were). It sounded insane (hitting it with a mallet), but it worked. They said I should get a 400A solenoid and the 48V Trombetta (200A) just isn't strong enough for 600A controller. The Navitas does give real time amperage reports, and it's amazing, quick acceleration is one thing, but regen braking causes HUGE amperage spikes.

Anyways, the cart is working, and I have regen way down (0), brake bias gain way up and acceleration amperage way down. I can still go 30+, and haven't pushed this thing, but I am worried about welding the solenoid.

I'll attach some logged photos of an ultra conservative ride yesterday after I free'd the solenoid with settings way down and you can see any moderate acceleration or braking causes large amperage measurements.

Navitas recommended the MJZ 400A HD Solenoid, I did manage to get a 200A MJZ HD to test if the soft welding issue disappears, but I think I should've bought the 440A controller or need to pickup a 400A solenoid. I'm not trying to do wheelies, I just want a reliable cart. The one issue with the recommended 400A solenoid is doesn't direct bolt-in given it's size. I'm going to try the MJZ 200A HD direct bolt which has an 800A surge/peak rating and should be slightly beefier than the Trombetta.

While I had a hiccup with the Navitas within my first day, their support is real good and the real-time diagnostics and OTF are pretty cool. Given this is now a pure hobby, I want to get my hands on a tuned 350A and provide an unbiased report, I am ultimately seeking a worry-free cart that does 30mph, can handle mild hills and accelerates reasonably but not aggressively. I've got no desire to drag race, do wheelies or offroad, I just want a worry free cart that can do 5-6 miles round trip at 25-30.

I'm impressed with the Navitas tune'ability, although I'm still working on braking refinement, but there is a gain adjustment and braking is getting more refined after subtle adjustments.

Nice thing is now I have a perfect 235A Curtis without error codes and a 48V Trombetta with <30 miles on it, so I'm building my test array of equipment, but I am just wondering what peoples' thoughts on the solenoid are. Maybe this controller is providing excessive amperage and the solenoid becomes the weak link...

[sigfla45]

Call Scotty with cartsunlimited and just get the 400amp solenoid. If you can install the navitas you can install the larger solenoid.

[DB Cooper]

Originally Posted by sigfla45

Call Scotty with cartsunlimited and just get the 400amp solenoid. If you can install the navitas you can install the larger solenoid.

Thanks. Installing isn’t an issue, just trying to find the right solenoid. Ideally finding one that can mount to the resistor cage directly.

[sigfla45]

Originally Posted by DB Cooper

Thanks. Installing isn’t an issue, just trying to find the right solenoid. Ideally finding one that can mount to the resistor cage directly.

I assumed you were worried about the larger ring terminals. Didn’t think about the physical mounting. I am sure others have done it here and there are potential solutions. Maybe navitas has a bracket or suggestion

[jr5018]

Keep us updated Coop, I am very interested to see how it works out.
I made a bracket out of some thin steel plate from ACE hardware. Just cut with shears bent drilled holes painted and popped it right in because I used a TXT 48v sol instead of an RXV sol.

[sigfla45]

I wonder if you can just use the Alltrax 400a bracket and make it work on the RXV?

[usgicollector]

You would think that everything you need would come with the kit.

[DB Cooper]

Originally Posted by usgicollector

You would think that everything you need would come with the kit.

Yeah, one would think. It seems most of the people running these all update their solenoid. I’m going to try and talk to them today and get more background. In the interim I’m monitoring amperage. Navitas doesn't make a solenoid that I'm aware of, and many people may have different solenoids, so it's not surprising they don't include one. Similarly, it's like not including higher gauge wiring, although to my surprise they did provide one short 2AWG cable for the B+ to Solenoid, although I already have one so I didn't use it. That said, it would be nice if they made a more clear recommendation if one was needed. When I spoke with them, they seemed to think this was a newer issue and something they could resolve in a software update as soon as this week...

From what I understand, the 48V Trombetta is rated for 200A continuous, 300 for up to 1 minute and 400A for 30 seconds. You can see from my attachment that it’s acceleration and particularly hitting the brakes that causes high amp spikes.

[molfpedal]

I am using the 36v Trombetta solenoid that was in my 2011 RXV with my Navitas TAC2. I sent Coop my setups for my TAC2. I see in excess of 280 amps for very short bursts on mine with no issues. I have not had an issue since my first Tac2 fried Regen circuit.
I believe that the problems with Coop's are related to the 23" tires. Bob Boyce or Sergio can answer that question better than me though. Maybe one of them will respond.

[DB Cooper]

Originally Posted by molfpedal

I am using the 36v Trombetta solenoid that was in my 2011 RXV with my Navitas TAC2. I sent Coop my setups for my TAC2. I see in excess of 280 amps for very short bursts on mine with no issues. I have not had an issue since my first Tac2 fried Regen circuit.
I believe that the problems with Coop's are related to the 23" tires. Bob Boyce or Sergio can answer that question better than me though. Maybe one of them will respond.

It's possible, obviously the 23s require that extra amperage which is why I bought this. I can tell based on my conversations they're tracking this solenoid (2-8 error) and are very interested in it and said it's a relatively new thing and they think they can improve/fix it in software.

I may need to look into the max current setting, I'm not in front of the app, but where exactly in the app is that? I'm going to try and get a hold of them today.

Thanks for the help, when I told them about the error, the first thing they asked/assumed was if I was running lithium, they did admit brand new LA could cause this, so possible it is regen influx current.

One other thing that I remember, by default the Navitas assumes RXVs use the 36V controller, but as we know, later years switched to a 48V, so I did have the solenoid voltage improperly set to 36V since I went out and rode without reviewing the settings (NOTE: this is how most people use Navitas, you have to get the Dealer/TestFlight app to even see this stuff). The engineer I spoke with did feel that it could've exacerbated the situation having the wrong voltage set in there.