Would a different portable charger work better on a GFCI circuit?

[josh0]

I know that Rivian’s portable charger isn’t the only one that doesn’t always play nicely with GFCI protected circuits, but are some more problematic than others?

I’m going to have to leave my R1T parked for an extended period (roughly 30 days), and will have the option of plugging it into a GFCI receptacle. I’d love to leave it plugged in for peace of mind, but if it’s going to trip the GFCI it seems pointless.

Right now I have the Rivian portable charger that I keep in the truck, and a Grizzl-E Mini that I keep in the garage. Would the Grizzl-E be less likely to cause problems in this scenario, or is there a different option I might consider?

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[ElGuano]

As I understand it, GFCI doesn't trip on high load or overheat. It measures the current in the AC circuit and detects if there is a short to ground from the hot or neutral. This isn't the typical "my charger/plug melted down" risk you often see with EVs. And some chargers have GFCI functionality built in, so they don't need/recommend a separate GFCI at the receptacle or the breaker.

What exactly is the problem you're experiencing with the charger on GFCI?

 

[josh0]

As I understand it, GFCI doesn't trip on high load or overheat. It measures the current in the AC circuit and detects if there is a short to ground from the hot or neutral. This isn't the typical "my charger/plug melted down" risk you often see with EVs. And some chargers have GFCI functionality built in, so they don't need/recommend a separate GFCI at the receptacle or the breaker.

What exactly is the problem you're experiencing with the charger on GFCI?

I haven’t used it on this particular GFCI, but I have had problems with it tripping others in the past, and I know a lot of people have reported similar experiences.

The advice I’ve generally seen has been to put in a new GFCI receptacle, which is less likely to have problems, or move to a non-GFCI circuit. Neither option is available to me, as the receptacles are in a parking lot.

I realize there’s a chance there won’t be a problem at all, but if the GFCI trips, I may as well not have power at all, so will need to charge to a higher SoC than otherwise to ensure vampire drain doesn’t become an issue. In the past, I’ve seen up to 2% loss per day (though it has been better lately), so I need to account for up to 60% loss over a 30 day stay with enough left to make it to a fast charger.

 

[josh0]

To clarify, I’m not talking about an over-current issue. From what I understand. The built-in GFCI functionality in level 1 EVSE equipment can essentially interfere with the GFCI protection in a receptacle or breaker, and cause it to trip erroneously.

 

[ElGuano]

Gotcha, 30 days is a long time. I think others have have suggested 12v battery top-off to minimize this (from my own very short experience with the truck, most of the daily ~0.6%/day drain is from 12v battery maintenance).

I have outdoor GFCIs that trip regularly when it rains, but those haven't been associated with chargers. If the charger is tripping a GFCI, I'd be a bit more worried about where a current imbalance may be coming from. It's less likely that the GFCI itself is malfunctioning....

 

[josh0]

This is apparently a common issue with portable chargers. I’ve seen it reported by owners of other EVs, as well as a handful of discussions on this forum.

On the other hand, before I was able to get a 240V receptacle installed in my garage, my only way to charge was an extension cord to an outdoor GFCI 15A, which, while horribly slow and obviously inadvisable, actually worked without issue. So who knows. ?‍

 

[ElGuano]

This is apparently a common issue with portable chargers. I’ve seen it reported by owners of other EVs, as well as a handful of discussions on this forum.

Our Tesla Model X has been on a 120v 15a GFCI for....7+ years now, plugged into the mobile charger. It's never tripped once. Yeah, it's not a Rivian, but I wasn't aware it's a common issue. Interesting...

On the other hand, before I was able to get a 240V receptacle installed in my garage,

I believe if you do this today, you MUST have that receptacle branched from a GFCI breaker in order to be code compliant. So if it's really a GFCI conflict of some kind, you'd likely still run into it with an L2 receptacle?

 

[Rivian Owner]

Typically if the charger is hardwired it will have internal GFCI protection, but if plugged in, the receptacles or the breaker needs to be protected. GFCIs can get "trip happy" and need replacement. Keep in mind that it only takes 60 miliamps to trip the GFCI, so it doesn't take a lot of "leakage" to trip the protection.

I would test the outlet you are planning on using to see if your charger trips the circuit (sorry if you already posted it will?). If it trips, try another charger until you find one that works (Amazon has a 30 day return policy so you can try at no cost to find one that works). I think any brand could trip the breaker if it is borderline compliant. Sometimes if the charger has built in GFCI it can cause issues with the circuit protection device.

 

[Dark-Fx]

I'm not aware of anywhere to look up what the typical current used for doing the ground verification is for any particular EVSE.

 

[josh0]

Typically if the charger is hardwired it will have internal GFCI protection, but if plugged in, the receptacles or the breaker needs to be protected. GFCIs can get "trip happy" and need replacement. Keep in mind that it only takes 60 miliamps to trip the GFCI, so it doesn't take a lot of "leakage" to trip the protection.

I would test the outlet you are planning on using to see if your charger trips the circuit (sorry if you already posted it will?). If it trips, try another charger until you find one that works (Amazon has a 30 day return policy so you can try at no cost to find one that works). I think any brand could trip the breaker if it is borderline compliant. Sometimes if the charger has built in GFCI it can cause issues with the circuit protection device.

The problem is that this is in a paid-access lot that’s 2.5 hours away. So I suppose I could drive 5 hours round trip and pay for a day of parking to test receptacles to see if there’s a problem, but it seems more reasonable to just try and minimize the chances of there being a problem and prepare for the worst case scenario.

 

[josh0]

Our Tesla Model X has been on a 120v 15a GFCI for....7+ years now, plugged into the mobile charger. It's never tripped once. Yeah, it's not a Rivian, but I wasn't aware it's a common issue. Interesting...




I believe if you do this today, you MUST have that receptacle branched from a GFCI breaker in order to be code compliant. So if it's really a GFCI conflict of some kind, you'd likely still run into it with an L2 receptacle?

A hard-wired EVSE has its own built-in GFCI, and so does not need to be on a GFCI breaker to be code compliant. I believe that 240V receptacles are exempt from the GFCI requirement (but don’t take my word for it if you’re wiring it up yourself).

The issue appears to be when you have two stacked GFCI protective devices, as happens when you plug an EVSE into a GFCI protected circuit (whether receptacle or breaker).

 

[Rivian Owner]

A hard-wired EVSE has its own built-in GFCI, and so does not need to be on a GFCI breaker to be code compliant. I believe that 240V receptacles are exempt from the GFCI requirement (but don’t take my word for it if you’re wiring it up yourself).

The issue appears to be when you have two stacked GFCI protective devices, as happens when you plug an EVSE into a GFCI protected circuit (whether receptacle or breaker).

Just because it is 240 volts does not negate the GFCI requirement. I find it interesting that you can have a circuit for an arc welder, but still be required to have GFCI protection.

 

[racekarl]

I believe that 240V receptacles are exempt from the GFCI requirement (but don’t take my word for it if you’re wiring it up yourself).

The current US electrical code requires a GFCI on any circuit intended for EV charging, regardless of voltage or amperage.

As you note, most (All?) EVSEs contain an on-board GFCI. They almost always have some sort of self-test to ensure the connection to the wall is wired properly before they will initiate a charge. Depending on how the self-test works it can trip a GFCI upstream of the EVSE (e.g. the receptacle or a GFCI breaker).

FWIW, the user manual of the GIZZL-E Mini seems to indicate that it will play nice with an upstream GFCI:

"3 GFCI​

• The Charger is equipped with GFCI. Additional downstream GFCI is not required.​

• In locations where GFCI at the outlet is mandated by code, the charger will not experience​

adverse effects."​

https://grizzl-e.com/products/grizzl-e-mini/

 

[BCondrey]

I used a Rivian mobile charger on a 15A GFCI with no problems for about 6 months. If it trips a lot for you, you can start by replacing the GFCI outlet. It should work.

 

[SwampNut]

Just because it is 240 volts does not negate the GFCI requirement. I find it interesting that you can have a circuit for an arc welder, but still be required to have GFCI protection.

Ask me about the time I tried to use my TIG on a circuit with an AFCI....

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