40 amp circuit breaker for EV, 'handled' 40amps continuous

[petee_c]

Is that within acceptable operating parameters?

I have a n14-50 'flexible fast charger' from BMW for my EV. There are no dipswitches in it. It sets amps by the pigtail you plug in. Comes with the standard household n5-15plug sets automatically to 1000w, or the n14-50 that draws 40amps.

I have a 40amp breaker (used - free from family electrician); 30 ft run of 6awg wire to a n14-50outlet. I ran 6awg wire - I'd like to upgrade to a 50amp breaker when I get a new panel (got a full obsolete Federal Pioneer panel at the moment)

I usually set the charging limit in the car to 32amps (remembers it day to day). However I had changed it to 40amps when I was away on a recent roadtrip. We've charged it a few times since then. Just realized I hadnt switched it back to the home setting of 32amps.

I noticed today after a couple hours of charging, and reset it back to 32amps.

Anyways, I went to the breaker box in the basement. Most breakers IR thermometer'd at 68F, the EV breaker was 76F.

I charge at 7kW normally, just happened to notice on the dash the car was displaying a 9kW charge.

 

[micromind]

If the breaker is not overheating and not tripping, I don't see a problem. Yes, it'd be better if it were set to the lower current but as long as adjacent breakers are run at low current, a 40 will almost certainly handle 40 amps continuously.

 

[petee_c]

If the breaker is not overheating and not tripping, I don't see a problem. Yes, it'd be better if it were set to the lower current but as long as adjacent breakers are run at low current, a 40 will almost certainly handle 40 amps continuously.

thx.

it's run 5.5hrs at 40amps at least twice in the past few weeks without issue as well as a few other shorter sessions. I'll leave it set to 32 amps for safety.

at 32amps, i typically only charge 4-6hrs worth twice weekly to cover our day to day driving.

 

[sparky 1971]

The 80% rule is for continuous use which is defined as for more than three hours. While it was probably charging for more than that, no damage was done and since it's a Federal, there's no concern about the breaker tripping.

A breaker can run at or a little above it's rated current indefinitely.

 

[mm08822]

A breaker can run at or a little above it's rated current indefinitely.

Fur shur on the Federals!!

OP, 50A cb with a new panel is the way to go. Good to see you planned ahead for this.

 

[petee_c]

The 80% rule is for continuous use which is defined as for more than three hours. While it was probably charging for more than that, no damage was done and since it's a Federal, there's no concern about the breaker tripping.

A breaker can run at or a little above it's rated current indefinitely.

Yeah, the interwebs says bad things about the Federal Pioneer panel. This house was built in the late 80's, we moved here in 2005. No issues or signs of overheating in the panel.

We will be switching to a larger panel at some point. This one is full, and we need space if we want to add solar.

 

[allinon72]

I wouldn't be pulling any amp load on a Federal panel. Sure it's good now when you're looking at it but who knows in the future. And like the other guy said, you won't have to be worried about tripping breakers.

 

[cybrdyke]

Code says it should be a 50A breaker to charge at 40A.
Curious about the car, though....you're saying you have to input into the car's computer what charger you're using? I was under the impression that this was all done automatically when the car is plugged in. No? I know that on my EV it automatically knows.
CD

 

[kaffine]

Code says it should be a 50A breaker to charge at 40A.
Curious about the car, though....you're saying you have to input into the car's computer what charger you're using? I was under the impression that this was all done automatically when the car is plugged in. No? I know that on my EV it automatically knows.
CD

The issue is he plugs into a 50 amp outlet so the adapter tells the car it is on a 50 amp circuit and can charge at 40 amps. Some adapters limit it to 32A with a 14-50 some allow for 40A. The cable that came with my car only allows 32A using a 14-50 but the previous generation of cable allowed 40A.


petee_c

How old is your car? I thought Canada only allowed the 14-50 adapters for EV to use 32A since there are so many 14-50 outlets on 40A circuits.

 

[petee_c]

The issue is he plugs into a 50 amp outlet so the adapter tells the car it is on a 50 amp circuit and can charge at 40 amps. Some adapters limit it to 32A with a 14-50 some allow for 40A. The cable that came with my car only allows 32A using a 14-50 but the previous generation of cable allowed 40A.


petee_c

How old is your car? I thought Canada only allowed the 14-50 adapters for EV to use 32A since there are so many 14-50 outlets on 40A circuits.

my car is a 2023 BMW i4m50, it's 6 months old.

It has an onboard 11kW charger. You can limit the charge anywhere from 6amp to 32amp on Level 2 on the dash. I believe the limits are set on Level 1 by the charger.

The charger that came with the car is called a 'flexible' charger (EVSE). It has different pig tails that can connect to the brick, and then the brick has a 20' cable with a J1772 plug on the other end. The charger (EVSE) sets the limit by whatever pigtail is plugged in. Mine is limitted to 40amps on a n14-50 pigtail. If you had a 30 amp welding circuit in your garage and bought the corresponding 30amp plug, it would have the output set to 24amp (80% of that plug).

Aftermarket chargers (EVSE's) I believe can be set to the proper output on the charger itself by the user either in the menu if it has buttons, or by dipswitches inside or on the back of the device.

This is my understanding of how it all works.

 

[micromind]

my car is a 2023 BMW i4m50, it's 6 months old.

It has an onboard 11kW charger. You can limit the charge anywhere from 6amp to 32amp on Level 2 on the dash. I believe the limits are set on Level 1 by the charger.

The charger that came with the car is called a 'flexible' charger (EVSE). It has different pig tails that can connect to the brick, and then the brick has a 20' cable with a J1772 plug on the other end. The charger (EVSE) sets the limit by whatever pigtail is plugged in. Mine is limitted to 40amps on a n14-50 pigtail. If you had a 30 amp welding circuit in your garage and bought the corresponding 30amp plug, it would have the output set to 24amp (80% of that plug).

Aftermarket chargers (EVSE's) I believe can be set to the proper output on the charger itself by the user either in the menu if it has buttons, or by dipswitches inside or on the back of the device.

This is my understanding of how it all works.

Does it have provisions for a 208 volt 3 phase input?

 

[petee_c]

Code says it should be a 50A breaker to charge at 40A.
Curious about the car, though....you're saying you have to input into the car's computer what charger you're using? I was under the impression that this was all done automatically when the car is plugged in. No? I know that on my EV it automatically knows.
CD

true,

however, my n14-50 outlet is wired for 50amps, but I currently have it on a 40amp circuit breaker because: I am cheap, the breaker was free, and the 50amp breakers are unobtanium/$$$.

The EVSE/charger doesn't know that it's on a 40amp breaker, with the included m14-50 pigtail, it believes its on a 50amp breaker.

I will be changing out the panel in the next couple years, and didn't want to spend the money on a 50amp breaker that will only get used for a couple years.

 

[petee_c]

Does it have provisions for a 208 volt 3 phase input?

not the included charger for North America.

I believe for Europe this is a more viable option. My understanding that most homes in N America are 230-240 single phase. Too much expense for an extra 2kW charge.

You could by code hardwire a 60amp aftermarket EVSE (charger) which are somewhat readily available and get 48amp x 240v = 11kW charge.

 

[cybrdyke]

my car is a 2023 BMW i4m50, it's 6 months old.

It has an onboard 11kW charger. You can limit the charge anywhere from 6amp to 32amp on Level 2 on the dash. I believe the limits are set on Level 1 by the charger.

The charger that came with the car is called a 'flexible' charger (EVSE). It has different pig tails that can connect to the brick, and then the brick has a 20' cable with a J1772 plug on the other end. The charger (EVSE) sets the limit by whatever pigtail is plugged in. Mine is limitted to 40amps on a n14-50 pigtail. If you had a 30 amp welding circuit in your garage and bought the corresponding 30amp plug, it would have the output set to 24amp (80% of that plug).

Aftermarket chargers (EVSE's) I believe can be set to the proper output on the charger itself by the user either in the menu if it has buttons, or by dipswitches inside or on the back of the device.

This is my understanding of how it all works.

thanks. I get the concept of how the EVSE works. If this is a cord that's intended to travel with the car, then I get it.

What I'm wondering is why you'd need to make any adjustments on the dash. If your car is only capable of charging at 32A and you plug into an EVSE that's outputting 40 or 48 amps, you shouldn't have to do anything. The car should automatically just charge at 32A.
CD

 

[wyliesdiesels]

The 80% rule is for continuous use which is defined as for more than three hours. While it was probably charging for more than that, no damage was done and since it's a Federal, there's no concern about the breaker tripping.

A breaker can run at or a little above it's rated current indefinitely.

federal pioneer (canadian) is different than federal pacific...

 

[wyliesdiesels]

Yeah, the interwebs says bad things about the Federal Pioneer panel. This house was built in the late 80's, we moved here in 2005. No issues or signs of overheating in the panel.

We will be switching to a larger panel at some point. This one is full, and we need space if we want to add solar.

federal pacific NOT federal pioneer. AFAIK there werent any issues with federal pioneer panels....

 

[dcg9381]

Is that within acceptable operating parameters?

Dad just showed up with a BMW EV, It's on a 14-50R and the breaker is 60A, I told him 40A continuous is what we can do here.

The first question is "how hard do you need to charge?"

40A is generally more than enough to charge most EVs overnight. That's your 9.6KW. That's generally safe for all 14-50R and 50A breakers. Turn the car down to what you "need" overnight if you don't know the house's electrical capacity.

 

[petee_c]

federal pacific NOT federal pioneer. AFAIK there werent any issues with federal pioneer panels....

My (Canadian) Federal Pioneer uses the stablok breakers.... I thought that was the issue with the panels.

 

[SlappyWhite]

Online the story is very mixed/contradicting (Pacific vs Pioneer) Stablok from what should otherwise be good sources. high level....

Some say the Pacific breakers (US made) had QC problems in some batches and although the Pioneer (Canada made, so different factory) ones were the "same design" they did not have the same QC issues???

Other sources say bad design, so both are bad???

All I can say is I have some experience with the Canadian (Pioneer) and have witnessed more than a few "user error" shorts and over currents without a trip. Some side cutters that are now wire strippers, some drywall has scorch marks, and some melted copper wire to show for it. Hardly statistical in my case but my experience has me lean towards category two and to treat all Federal *** with suspicion. YMMV.

If there was one in my house, the panel would be on my upgrade list.

 

[rlitman]

thanks. I get the concept of how the EVSE works. If this is a cord that's intended to travel with the car, then I get it.

What I'm wondering is why you'd need to make any adjustments on the dash. If your car is only capable of charging at 32A and you plug into an EVSE that's outputting 40 or 48 amps, you shouldn't have to do anything. The car should automatically just charge at 32A.
CD

It's a negotiation. Both the car and the EVSE have limits. 40A is the most you can get out of a plug-in EVSE. Hard wiring lets you get up to 80A Level 2 at the moment (on a 100A breaker), but it's still up to the car to decide if it wants all that.

As for why you would do this? Well, perhaps you're on a time-of-use demand based electric rate plan and don't want to incur heavy costs some times of day? Or you have a 2-car garage and plug in two EVSEs at the same time and don't want to overload the panel.