Issues charging at home on 240v with the Portable charger

[thrill]

It took me a while to re-find it, but this 2 year old stack exchange discussion is informative. TLDR: It can be many things, but tripping after an hour is probably heat related, possibly with cheaper components involved.

https://diy.stackexchange.com/quest...ipping-when-charging-ev-after-about-1-5-hours

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[VSG]

Note that the Rivian portable charger will only draw a maximum of 32 Amps. It is deliberately limited. That is well below the continuous 40 Amps you should be able to draw from a properly wired 50 Amp circuit.

My first suspicion is the wiring. I think the portable charger is an unlikely cause, and the vehicle itself is an order of magnitude less likely than that.

But one thing I never see mentioned that may cause your problem:
The portable charger comes with two short adapter cables - one for NEMA 5-15 and one for NEMA 14-50. These short cables plug into the portable charger body. And because they plug in, they can also pull out of the body.

If you suspend the portable charger body from the outlet with no strain relief, then the short adapter cable WILL become separated over time. DON'T MOUNT IT THIS WAY, just dangling from the outlet.

The fit is tight enough that it will work for a while if it's just dangling there, but if it's hot out, the rubber softens, and it may be that it becomes easier to separate. Regardless, the weight of the portable charger body pulling down will eventually cause the body and the cable to separate just slightly, enough to trip the GFCI.

The portable charger body is designed to hang from a screw. Make sure you mount it properly and don't just let it dangle from the outlet. And if you're using the portable charger on the road, say at a campground with a hookup, then bring a bungee of some other method of providing strain relief for that junction between the adapter cable and the charger body.

 

[jrmbadger]

ut one thing I never see mentioned that may cause your problem:
The portable charger comes with two short adapter cables - one for NEMA 5-15 and one for NEMA 14-50. These short cables plug into the portable charger body. And because they plug in, they can also pull out of the body.

If you suspend the portable charger body from the outlet with no strain relief, then the short adapter cable WILL become separated over time. DON'T MOUNT IT THIS WAY, just dangling from the outlet.

The fit is tight enough that it will work for a while if it's just dangling there, but if it's hot out, the rubber softens, and it may be that it becomes easier to separate. Regardless, the weight of the portable charger body pulling down will eventually cause the body and the cable to separate just slightly, enough to trip the GFCI.

The portable charger body is designed to hang from a screw. Make sure you mount it properly and don't just let it dangle from the outlet. And if you're using the portable charger on the road, say at a campground with a hookup, then bring a bungee of some other method of providing strain relief for that junction between the adapter cable and the charger body.

Excellent point. I'd also add that the fit is tight enough that sometimes it's hard to fully insert the plug into the body of the charger. The "shoulders" of the plug should not stick out past the adapter body at all - they should be flush. Make sure to push it as hard as you can go to make sure it is fully seated in the first place.

Another issue that Tesla mobile connectors had recently is they had a bad batch of NEMA 14-50 plugs that were causing the same issue. It wasn't the mobile charger itself, but the NEMA 14-50 plug.

 

[socaladam]

The problem is the GFI is required by the US electrical code, according to the electrician who did the work, and they will not install without one. So my only option would be finding somebody who does it without a license or trying to do it myself neither of which I’m comfortable with doing.

I have a Leyman’s understanding about heat in electrical circuits, and my initial instinct was that a bad GFI is tripping at a heat range that it should not be. However the hottest temperature I saw on the face of my GFI prior to it tripping was only 110°F and unless the GFI is truly faulty, I cannot see that temperature causing a trip.

I do know that the electrician used six gauge wire for the install, but I do not know the type that was used. The length of the run from my circuit breaker to outlet is approximately 10 to 12 feet. I do have the correct EV specific Nema outlet, although the electrician had to install that on his second visit.

When I get back home on Saturday, I will try charging again at 30 A and see what the result is with the new circuit breaker.

ours is installed with 6 gauge THNN and my run is about 30 feet. No GFI breaker, and we don’t use the Rivian charger. I use our Audi portable charger and get 9kw to the R1S which equates to about 38 amps

never once tripped the breaker.

I’ve never seen our Rivian charger pull more than 8kw which calculates to 32 amps.

What is your observable charging rate when you plug in?

 

[HaveBlue]

1. GFCI does not test just during charge initiation. It tests continuously 24 hours per day.
2. A GFCI does not need a ground lead egc to function however the portable charger does.
3. A GFCI is required for circuits of certain types, in damp/wet locations in some jurisdictions.
4. There are two kinds of GFCI breakers. One type protects against loss of life. The other protects against equipment damage.
5. When you install a GFCI behind GFCI you run the risk of one trippping the other if both are loss of life type, the upstream one is an older style that doesn't account for EVs, or you aren't allowed to use an equipment style gfci breaker.
6. A GFI is similar to a GFCI.

 

[Time2Roll]

I would swap the breaker for a non GFCI. Takes about 3 minutes tops. Take it down to the hardware store and match it up.

The EVSE already has GFCI.

 

[VSG]

I would swap the breaker for a non GFCI. Takes about 3 minutes tops. Take it down to the hardware store and match it up.

And that would be against code in most places, qualifying you for the Darwin Awards if something eventually went wrong.

 

[Time2Roll]

The outlet may need a GFCI but not specific to EV charging. So yes when the adapter is unplugged and you stick something in the socket with your bare hands there is a high risk of injury. I would sooner put a locking cover on the outlet so no one can mess with it. Locked on or locked out. At least my vehicle will be charged.

 

[VSG]

The 2023 version of the National Electric Code does require a GFCI on an outlet used for plug-in EV chargers. While some municipalities may still be using an older version of the NEC, it's only a matter of time before they update.

 

[PWHesson]

As we were trying to sort this out in the spring I recall reading that a lot of the chargers do not like gfi circuits. Yes, a wall plug is a garage is required to be on a gfi. We had a 30 amp plug prewired and can't recall if they really had a gfi breaker. We did have a gfi breaker in that same panel that was getting tripped by low voltage window shades...go figure, it was just a bad breaker. I decided to just replace another unused breaker and put in a heavy service for a 50 amp wall charger and hardwire it in so that no gfi is required. Bought the ChargePoint and been happy with it. Agree with a prior commenter that using the portable charger forever is not really a good option.

 

[blturner]

BTW. The charge current ramps up from the start and the one hour mark may be related to that ramp rather than heat alone.
No touching a 50 amp circuit will not put 50 amps through your body. It will put however many amps 240volts can push through your body. Not 50. Probably enough to kill you, but not 50. It only takes a dozen or so milliamps to kill you if it goes through your heart.
Side note touching one contact of a 240v outlet typically only subjects you to 120v because ground sits between the two hot wires. To get 240v you have to touch both hot contacts. That is harder to do.

The short distance from the breaker box to the outlet means that the wire used is less likely to be the issue but also means it is cheap to use thicker wire.

Ohm's law says that increased resistance decreases current. Many devices and loads will increase current in response to lowered voltage because they are trying to get to a particular power level. It is more than can be explained on a forum, I just wanted to point that out so it did not become common to think that more heat always equals more current because it does not always.

 

[Rivian Owner]

[/QUOTE]
Ok, while your comments are mostly correct, some statements aren't correct. 1. If the resistance is high in a circuit because

Before I switched to the Tesla Wall Connector, I used a NEMA 14-50 outlet exclusively with my Tesla mobile charger on a GFCI breaker and had exactly ZERO nuisance trips. NONE. There are many many many more of us who have successfully used a GFCI breaker with mobile chargers for years and had no issues.

GFCI works by measuring current on the hot leg and comparing it to the current on the neutral leg. If they are equal, that means that there is no ground short. If they are not equal, there is no short. The only issue with an EV charger is that sometimes you may get a trip when starting a charge, as the charger leaks a small amount of current to ground to make sure the outlet is grounded. This may trip a sensitive GFCI breaker, but would not do so during the middle of a charging session as you have indicated.

Removing the GFCI is unsafe and I would not recommend it. Consider the situation when someone is unplugging your EV charger. If you don't shut off power at the breaker there is a risk of electrical shock. Those metal prongs on the plug are fairly long and it takes a bit of force to remove them. Let's say you accidentally make contact with those prongs as you are removing them. Now you have 120v or 240v (depending if you make contact with just one hot leg or both) @ 50AMPS of current running through you. Not something you wanna experience. On the other hand, if you have a GFCI, most likely the breaker will trip to protect you and keep you alive.

If the breaker is tripping there is likely a problem in the circuit, wiring, or mobile charger. Breakers tripping in the middle of a charge cycle do so because they are too hot. That's how breakers work - they get hot and trip (most breakers). Inside a typical breaker, there is a bimetallic strip that acts as a heat sensor. When excess current flows through the breaker, the wire and the bimetallic strip heat up. Due to thermal expansion, the two metals in the strip expand differently, causing the strip to bend. This bending action trips the breaker and stops the electrical flow to prevent overheating and potential fires.

Excess current flowing through the wires can be caused by resistance downstream. This resistance can be caused by insufficient wire size, loose connections, poor connections between the outlet and the plug, and poor connections between the plug tail (the NEMA 14-50 tail that came with the mobile charger) and the mobile charger itself (- its pretty stiff and you have to push really hard to get it to properly seat). Over time, these problems can cause the circuit to heat up. As the circuit heats up, the resistance goes up further (heat increases resistance). This causes a positive feedback cycle that eventually trips your circuit. This can also happen over time due to expansion and contraction of the metal wires and contacts due to heating the wires which may loosen the wires.

If I were in your shoes, I'd rule out the Rivian charger first, then I'd ask some serious questions from my electrician about the supplies used (wire sizes - see my earlier post - and outlet choice).

I'm not an electrician, but I installed my own NEMA 14-50 outlet and then later converted that to a Tesla Wall Connector on a 60 amp circuit and then added a second Wall connector to charge my rivian. I extensively researched the electrical code and how to do it safely prior. I have never had an issue with nuisance tripping. When I got my NEMA 14-50 inspected, the main issue the inspector wanted to verify is that I used a GFCI breaker.

On the other hand, there are tons of stories in the forums of licensed electricians installing wire that is too thin to handle the continuous loads of an EV charger or cheaping out on non-commercial grade outlets.

Take a look at this video from Tom Moloughney of State of Charge - he knows what he's talking about. State of Charge

JRM,

While I agree with some of your comments, some of your statements are inaccurate or need some clarification.

1. When the resistance in a circuit is high, whether from bad connections or from the wire heating up, current goes down (ohms law). If you have a reduction in current the current flowing through the breaker is reduced, so it wouldn't cause the breaker to trip. There is no way for the breaker to sense anything other than the current flowing through it (not talking about GFCI or AFCI here).

2. We are talking 240 volts here, so two legs in opposite phases (120 volts each making the potential between the two hot wires 240 volts). The GFCI circuit works a little differently as the two phases will cancel each other out, so no current on the neutral wire if they are both pulling the same current. I bring this up because the GFCI has to take the two phases into account (as opposed to a single phase 120 volt circuit) because you will have some current on the neutral wire if the two opposing phases aren't drawing the same current, but the current on the neutral may be some fraction of the total current on either hot conductor, because you'd still have some cancellation of the two phases of current. Probably more than you wanted to know, but the 240V split phase GFCI breakers have more "math" to do than to just compare the outgoing and incoming current, and the added complexity can cause a higher number of false trips.

3. GFCI breakers have a history of false trips more frequently as they age and with more and more trips of the circuit protection. As these breakers are complex, it is possible to have multiple "new" breakers that falsely trip. If you have a GFCI in the panel and another in the equipment (in this case a portable charger) there is a higher likely hood that you will have false trips of the breaker in the panel. I've seen circuits that perform without problems and at other times circuits with a lot of issues with false trips. We used to try and hardwire grounded devices if possible, to eliminate the need for these problematic costly breakers.

4. Even if you got your fingers across both the hot wires/prongs, the likely hood that you'd draw 50 amps across your body has nothing to do with the rating of the breaker. If the resistance of your body's connection was low enough you could draw a lot more current than the breaker's rating as most circuit breakers are designed to allow for inrush current. However, the resistance of your skin is likely higher than the resistance of copper wire, and again, thinking about Ohms Law, higher resistance equals lower current, so in most likely hood you wouldn't get 50 amps of current flowing through your body. If you want to test this out, first shock yourself with the 240 volts with dry skin, then try cutting yourself and using the cuts to contact the wire (just kidding, use saltwater to improve the conductivity of your skin). Don't try this at home boys and girls!

I agree with trying to find another charger to test your circuit to see if the test charger and vehicle gives you the same symptoms. This would eliminate the charger and the vehicle as the problem. If you still get a trip on a different circuit, the other thing to eliminate is the vehicle by trying to charge a different EV with the original circuit and charger to see if you get the same symptoms. If both the EV and the charger test OK, then your problem is definitely in the circuit, whether the GFCI breaker, the wire or maybe a nick in the insulation, or something else your electrician has done incorrectly.

It sounds like the electrician has been willing to try and eliminate the breaker, so kudos to him. However just parts swapping without proper diagnostic procedures is just a hit or miss and doesn't really tell you which component is causing the issue. If you can demonstrate that the EV works fine on another similar circuit, and the charger performs equally well, then the burden is back on the electrician to find the issue with their work. Pointing fingers without having properly diagnosing things is just going to create a lot of animosity without solving the issue.

 

[Kymman]

I had the same issue. Our Electrician installed two 240v/50A outlets (one on each side of the house). initially the breaker would trip about an hour into charging. After trying various things like lowering the max charging amperage or trying the other outlet (same issue), the electrician changed out the brand of breaker from GE to Siemens and that solved the problem. He relayed that the GE brand is not as consistent and reliable as the Siemens. He mentioned that the rule of thumb is to match the breaker brand to the electrical box which was GE.

 

[FraserC]

I've mentioned this before but saw nothing that suggested anyone read it, so here goes: the most critical aspects in a new electrical circuit installation include correct wire gauge, appropriate circuit protection, and "adequate connections". I'm not an electrician, but as a mechanical engineer I do understand high resistance electrical connections - and the fact that these can cause focused heat. No coincidence that one of these connections is right at the breaker - where heat can trip it.

Proper connection theory should state that the contact surface area in a screwed compression joint should require that this 'clamped area' must be in excess of the cross sectional area of the conductor. Why? Because if it is ANY less, then heat in the circuit WILL be maximized here. So if you take the solid or twisted conductor and torque the screw but achieve less contact area, then you have an inadequate connection where heat will be focused.

Not to malign any pro electricians here, but I would suspect that not all of them are aware of how important this recommended practice is. Infra red thermal scanners are quite inexpensive now, and measuring the temp of the connections in this new circuit is a very good idea to troubleshoot a new circuit problem like this!

 

[stardustracer]

Not sure if this adds anything, but I just took delivery of a 2026 R1T with NACS and had trouble witih my Tesla mobile charger. It would fail to start charging, getting stuck in a loop, and a red light on the mobile charger would flash. This mobile charger worked fine for 5 years charging my model 3. After several attempts at removing and inserting the nacs plug i could get it to start working and it would charge the whole sesion without issue. But it took 10-12 attempts, which of course is not ideal. I tried another Tesla mobile charger and had the same behavior so its not isolated to a single charger. I finally broke down and got a Rivian mobile charger and it works no problem. So in my experience Tesla mobile chargers don't seem to work that well with the new NACS R1s.

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