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Discussion Starter · #1 ·
Just got my i40 eDrive40 today. I previously owned a 2017 Chevrolet Volt and has installed a Juicebox to charge it - it worked well for 4.5 years before I sold the Volt in anticipation of receiving the i40.

Today I tried to connect the i40 to the Juicebox and the BMW displayed a compatibility error. I then tried changing the setting to limit the current to the BMW at 32A and that tripped my breaker. I finally tried plugging in the BMW supplied fast-charger to the 240V outlet used by the Juicebox, and I tripped the breaker again. Finally I reduced the BMW to 20A and it seems to be charging, albeit slowly.

I checked the breaker in my basement that feeds the sub panel in my garage which has a dedicated breaker for the 240V outlet, and it's a 30 Amp breaker. That would explain why it trips at 32A charging. Thinking back 5 years, I believe we decided to use existing lines going to the garage for the 240V outlet, and thought it OK because the Volt did not need that much power. Obviously the BMW is different.

The simplest fix would be to swap the 30 amp breaker with a 50 amp breaker - but I am concerned that the lines themselves may be rated for only 30 amps and that might be a hazard. Is there an easy way to determine if my existing wires are capable of carrying 50 amps? The alternative would be to run new wires through my basement to the garage to upgrade the power going in.

Thoughts?
 

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Just got my i40 eDrive40 today. I previously owned a 2017 Chevrolet Volt and has installed a Juicebox to charge it - it worked well for 4.5 years before I sold the Volt in anticipation of receiving the i40.

Today I tried to connect the i40 to the Juicebox and the BMW displayed a compatibility error. I then tried changing the setting to limit the current to the BMW at 32A and that tripped my breaker. I finally tried plugging in the BMW supplied fast-charger to the 240V outlet used by the Juicebox, and I tripped the breaker again. Finally I reduced the BMW to 20A and it seems to be charging, albeit slowly.

I checked the breaker in my basement that feeds the sub panel in my garage which has a dedicated breaker for the 240V outlet, and it's a 30 Amp breaker. That would explain why it trips at 32A charging. Thinking back 5 years, I believe we decided to use existing lines going to the garage for the 240V outlet, and thought it OK because the Volt did not need that much power. Obviously the BMW is different.

The simplest fix would be to swap the 30 amp breaker with a 50 amp breaker - but I am concerned that the lines themselves may be rated for only 30 amps and that might be a hazard. Is there an easy way to determine if my existing wires are capable of carrying 50 amps? The alternative would be to run new wires through my basement to the garage to upgrade the power going in.

Thoughts?
You need to look at the gauge of the wires; I highly recommend having a licensed electrician do this; it's no joke and a common source of electrical fire.
 

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In simple terms to calculate the power at 20A its 240v X 40A = 4.8kw.
So you have to work out how long it will take to charge at 4.8kw
All I can find in a simple search is the following
3kw = 27.9hrs
7kw = 12hrs

So in rough terms I'd estimate 20hrs. That's rounding figures e.g. 28hrs instead of 27.9 and 5kw instead of 4.8. So it's probably going to take a bit longer than 20hrs but that's a good guide.

Obviously that's from flat to full.

My recommendation would be to get a competent electrician to review and upgrade whats required. Because whilst the feed to the garage might be capable of taking 32A we don't know what else us going on in your house. For example you main incoming fuse might only be 60A and if your using an electric cooker/shower rated at 30A you can see if you upgrade your mobile to 32A you will blow your main fuse and thats a call to your electricity supplier to replace at a cost and a serious discussion about who performed the illegal upgrade.

The above example is based on UK conditions but I can't see things being too different, if they are I apologise but you get the idea of the example.
 

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I think I would wait and see if the "slow" charging is a real issue.

I have approx 20 hours to recharge my i3 at home from 0 - 100 %. In the three years I have had the car, I have had approx 5 trips to the local fast charger, because I could not wait for the home charger. maybe half of them could be eliminated with a faster home charger. I think my cost of USD 1500 for an upgrade is not worth it.

I normally plug in in the evening at 40 - 60 percent, and it is at/near 100 percent the next morning.
If I have driven the car down to nearly zero percent - I will have limited range the next day : 60 - 70 percent.

With an i3 and an i4 I think I will have more flexibility regarding charging - and one of the cars will always be at nearly 80 (i4) or 100 percent (i3).

One reason to have a faster charger is that my electricity prices varies every hour. Sometimes I would have liked to charge more in the low price hours (sometimes between 01:00AM and 04:00AM)

I am considering an upgrade of charger and installing solar panels .
 

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Do not just swap the breakers. Most likely you have 10g wire with your 30 amp circuit. You need 6g wire for 50 amps (and 50a gfci breaker in garage). Can you see the existing wiring? You should be able to tell the gauge if so (labeled). You could also check the panels and the outlet itself to see the wiring. Just need to be careful if you’re playing around in the panel or at the outlet (cut power off).

Also is your outlet a nema 14-50? That should not be on 30amp circuit.

I don’t understand why the i4 doesn’t have 24amps as a charging limit option (maybe something they can update). The only way to charge at 24amps would be to get a 30amp EVSE and set the car at no limit.

20amps will give you 4.8kW. You’d be looking at ~17 hours to go from 0-100%. Staying with the general best practice and going from 20% to 80% would be ~10 hours 15 mins.
 

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Discussion Starter · #7 · (Edited)
Do not just swap the breakers. Most likely you have 10g wire with your 30 amp circuit. You need 6g wire for 50 amps (and 50a gfci breaker in garage). Can you see the existing wiring? You should be able to tell the gauge if so (labeled). You could also check the panels and the outlet itself to see the wiring. Just need to be careful if you’re playing around in the panel or at the outlet (cut power off).

Also is your outlet a nema 14-50? That should not be on 30amp circuit.

I don’t understand why the i4 doesn’t have 24amps as a charging limit option (maybe something they can update). The only way to charge at 24amps would be to get a 30amp EVSE and set the car at no limit.

20amps will give you 4.8kW. You’d be looking at ~17 hours to go from 0-100%. Staying with the general best practice and going from 20% to 80% would be ~10 hours 15 mins.
Garage outlet is certainly a nema 14-50. It runs into a sub panel that powers two garage door openers (each on a 20 amp breaker), the garage lights and regular outlets, and one outdoor set of lights (with a 15 amp breaker). There are a total of 5 breakers in the sub panel, counting the double pole feeding the nema 14-50 as two (its a double pole 25 amp breaker, not a 50). There is no GFCI, I presume because the Juicebox that plugged into the nema 14-50 did not need it (does it have an internal GFCI? I am not sure). I was surprised when I went to the main panel in my basement and saw the breaker feeding the garage sub panel was only 30A (it's a square D mini-breaker, 30A double pole). I had thought it was 50A (I have a double pole 100A/100A breaker feeding to my pool house sub panel for the pool pumps etc).

Wiring looks like it must be upgraded - I need to get a 50 amp breaker for the nema 14-50, and I need 6 gauge wire to support it. Looks like I will be finding an electrician to pull cable etc. As things stand now, not only does the garage sub panel have 30 amps feed for 2-20 amp breakers, 1-15 amp breaker, and 1-25 amp double pole, but it also powers my wine cellar A/C. It is way too underpowered.
 

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Discussion Starter · #9 ·
Got electrician in today and going to address next weekend. Best option is to run 100 amps from basement to garage sub panel so we future proof. Other option is to run 50 amp to the Nema outlet, but does not deal with possible second EV for my wife, nor the fact that I have too many units on 30 amp circuit as is.

(note: electrician told me that the existing pipe from sub panel to Nema outlet cannot handle 6 gauge wire - too thin)
 

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Got electrician in today and going to address next weekend. Best option is to run 100 amps from basement to garage sub panel so we future proof. Other option is to run 50 amp to the Nema outlet, but does not deal with possible second EV for my wife, nor the fact that I have too many units on 30 amp circuit as is.

(note: electrician told me that the existing pipe from sub panel to Nema outlet cannot handle 6 gauge wire - too thin)
Nice!

That’s why I hire experts…
 
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100 amps would be nice! What size is your main panel, 400 amps? To swap a 30a circuit for another 100a one is a nice luxury, given you have 100a for your pool sub.

You may be pushing it down the line if charging two EVs at 40amps each with the other circuits in use. The continuous load for the EVSEs alone would be at the “max” for the circuit.

My set up is 50a (14-50) with a Neocharge splitter and it works great for two EVs. Most don’t have a need to charge two EVs simultaneously at full power. Neocharge also allows dual charging up to 40a total if need be.
 

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One other consideration - a 14-50 receptacle requires a neutral, so make sure one is run. Some stay away from the neutral, as it‘s not used for car charging. The receptacle though dictates it, given one could plug something else in that needs it. The neutral is also needed for a GFCI breaker, with GFCI becoming the norm in garages now. A GFCI 50a breaker is $140 vs $12 at Lowes as an example (Square D).

The GFCI breaker should not interfere with the charging process.
 

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One other consideration - a 14-50 receptacle requires a neutral, so make sure one is run. Some stay away from the neutral, as it‘s not used for car charging. The receptacle though dictates it, given one could plug something else in that needs it. The neutral is also needed for a GFCI breaker, with GFCI becoming the norm in garages now. A GFCI 50a breaker is $140 vs $12 at Lowes as an example (Square D).

The GFCI breaker should not interfere with the charging process.
Seems Chargepoint and possibly Juicebox recommend a non GFCI breaker as people have been experiencing tripping due to dual GFCI's. Especially with plug in installation.

From Chargepoint:

Can I install Chargepoint Home Flex on a GFCI Breaker?

Yes. However, if local codes require a GFCI breaker for plug-in installation, ChargePoint recommends a hardwire installation. We do not recommend using a GFCI breaker as the Home Flex already has integrated charging circuit interrupting device (CCID) protection. Using a GFCI breaker in the panel, especially with a plug-in installation, can cause nuisance breaker tripping in certain circumstances and interrupt charging.
 
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Yes many recommend against a GFCI breaker (guess it's the easy way out for them, push hardwired to avoid any potential nuisance trips). The GFCI breaker has a much lower threshold to trip than the EVSE. There's a few other factors that'd be more likely to cause nuisance tripping, e.g. loose connections, failing receptacle, etc.

I've seen zero nussiance trippings personally using Clipper Creek and the BMW fast charger, coupled with a UL listed splitter (Neocharge).
 

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Let me ask differently the threshold question for now - how long will it take to charge my battery when limited to 20 amps of power?
The car and MyBMW app will tell you exactly how long it takes to reach the charge target when charging. Just set the current limit to 20a in the car, plug in, and look at the dash.

All great advice about getting an electrician to review IF you need an upgrade. But do the math on whether you really NEED faster home charging before the expense of an electrician. You've already got a 14-50 that's worked great for years with your Volt. You don't need to charge an i4 at 32, 40, or 48 amps unless your daily mileage requirements demands it.

240v/20a will give you ~5kw charging. From my experience in my ed40, that will replace ~5%/hour or about 15-20 miles/hour. So overnight, 12 hours, should replenish ~60% charge, or ~180 miles of range. That's a decent overnight charge for many unless you're truly burning through 180+ miles every day.

You could also buy another EVSE that allows a 24-amp limit. Then you don't have to tell the i4 to current limit itself at 20a (sidenote, seems odd BMW didn't give us a 24a limit), you'd still be safely at the 80% current rule on a 30a circuit, and you'd get slightly faster ~6kw charging.
 

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Totally agree, but if going the route of two EVs down the line then it'd best to upgrade all at once.

I still would like to know why the Car doesn't have a 24 amp limit setting - makes no sense given the prevalence of 30amp circuits here in the US. Having to buy another EVSE to gain 4 amps (~1kW) is definitely not worth it imo.
 

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Discussion Starter · #17 ·
My Juicebox has a 24 amp setting - I will try that next time I do big charge. Driving EH-NYC today and back tomorrow - plan is 230 miles or so without charging. So I will get back Tuesday night and want to replenish quickly. So will see how 24 amps does with needing a full charge on Tuesday night. I will bring MyBMW setting back up to 40 amp and let the Jukebox be the limiting factor.

I have two reasons for wanting to upgrade this. (1) I expect it to be slow process. I will be doing drive to/from NYC frequently (few times a month) and prefer not having car DOA for many hours when I get back. (2) I have real concerns about pushing the charging at 24 amps on this circuit. The breaker for the Nema plug at the sub panel is a 25 amp double, but the main breaker feeding the circuit is only 30 amp. And it is shared between my EVSE, wine cellar HVAC, freezer, and two garage door opener motors. Bad design as is. I should upgrade the circuit to at least 50 amp, but figured once I am upgrading, might as well do as much as I can for future needs.
 

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Makes sense. You should not have anything else on a 240v EVSE circuit. That's an unusual setup; especially having garage door openers and freezers on a 240v circuit.

If you've got enough money for a wine cellar HVAC, call an electrician to sort this out properly. ;)
 

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Discussion Starter · #19 ·
i did. Electrician came sunday and returns tomorrow. The electrician who installed the EVSE for the Volt messed up - he most likely did not see the HVAC on the line. I only realized they chawed the breaker when I was leveling the breakers last year. HVAC is not in the garage - not sure how it got onto the circuit that feeds the garage sub panel. I suspect the electrician who installed it looked for nearest 30 amp circuit he could find. At that time, all garage powered were the door openers and the lights, so adding made sense. But the guy who put in the Volt charger did not realize the lines had been tapped into before exit from basement to garage (I am only speculating).

I am luck I have had no major issues to date, but next to correct ASAP.
 
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