JuiceBox

[jadnashuanh]

In the USA, to pass code, the hardwired device must have the required circuit breaker and wiring to support the maximum that the device can provide based on the installation instructions and usually, based on the data label. If the device says it can draw 40A, based on the way the USA codes are written, the supply wiring MUST be 125% of it since it is considered a potential constant load. So, it should have a 50A breaker and related wiring to support a constant 40A load, regardless of what your car can draw from it...with 4g wire, I think you would be okay to install a 50A breaker...a 40A breaker only needs 8g wiring. If you did have a vehicle plugged into it that could use 40A, with that 40A breaker, you might end up tripping it over time. But, the wiring is sufficient unless the wiring run is excessively long. The issue as I see it is two-fold: if the data label says 40A, you can't use a 40A breaker; and, since you can't permanently derate the unit to 30A (since it is readily adjustable), the inspector probably won't be happy. Not that it won't work. Check the installation manual and data plate...to pass code, the supply must conform.

FWIW, the circuit breaker is designed to protect the WIRING, not the thing it is powering. So, it is okay to put in bigger wire than needed, but you can never put in smaller wire with a bigger breaker than called for by code. The UK is somewhat different...they put a fuse or breaker at the device. This could lead to a problem in the supply wiring.

 

[emotorwerks]

JuiceBox just came in and it looks like it's defaulted to 30A, which makes my electrician's question a non-issue.

Still I'm wondering if the car will take more than 32A if you change the JuiceBox setting higher, 'specially since it's got the onboard combo charger.

It might fry the onboard charger though: http://insideevs.com/bmw-to-finally-replace-i3-onboard-charger-to-restore-promised-7-4-kw-charging-rate/

We tried this, and the most an i3 would draw was 30A. Not insinuating that it's not possible for an i3 to draw more than 30 amps, it's just that we have not seen it, and have not been able to trigger this type of current draw. We are also looking shipping a 30-amp rated JuiceBox in addition to the 40-amp rated one. Considering this discussion, do you think that it would be a beneficial move?

 

[Tomasz]

We tried this, and the most an i3 would draw was 30A. Not insinuating that it's not possible for an i3 to draw more than 30 amps, it's just that we have not seen it, and have not been able to trigger this type of current draw.

did you try to lower voltage?

mine draws 7.4kW but that's only 30A @ 246V so that's to be expected. maybe it would draw more @ 208V?

 

[emotorwerks]

We tried this, and the most an i3 would draw was 30A. Not insinuating that it's not possible for an i3 to draw more than 30 amps, it's just that we have not seen it, and have not been able to trigger this type of current draw.

did you try to lower voltage?

mine draws 7.4kW but that's only 30A @ 246V so that's to be expected. maybe it would draw more @ 208V?

Yes, Tomasz. We tried and all it would do was 30A. Interestingly, one could apparently go up to 30A on 120V as well, except that most outlets would not take that, and the portable charging cord limits the i3 to 12A at that voltage. Similar behavior was observed with the LEAF and the Volt, if I recall correctly.

 

[jadnashuanh]

It seems like then that the i3 is current limited, and if your supply voltage is high enough, it can get to the full 7400W the KLE and whatever else the other module is called can draw together. That 30A limit continuous seems to correspond to the way the USA verses Euro ratings are - in Europe, they rate it at peak, not continuous like in the USA.

 

[Tomasz]

Yes, Tomasz. We tried and all it would do was 30A. Interestingly, one could apparently go up to 30A on 120V as well, except that most outlets would not take that, and the portable charging cord limits the i3 to 12A at that voltage. Similar behavior was observed with the LEAF and the Volt, if I recall correctly.

I know about 120V. I've tried it myself as I have 20A outlet at work and wanted to see how fast I can charge it on 120V. Right now I'm able to fully charge it on L1 within 10h.

 

[emotorwerks]

I know about 120V. I've tried it myself as I have 20A outlet at work and wanted to see how fast I can charge it on 120V. Right now I'm able to fully charge it on L1 within 10h.

Great to hear! That's a neat trick, isn't it?

 

[ted99]

I'm really happy with my Juicebox basic kit. I had some problems at the outset with trips and it turned out my new 40 amp breaker was defective. As part of the troubleshooting, with which emotorwerks was very helpful, the importance of keeping the wires through the GFI current sensor parallel was very evident and I posted a comment earlier, as a juicebox building tip, to shrink wrap the two wires together perfectly parallel during assembly.

As I understand emotorwerks is getting, or has already gotten, UL approval for the juicebox. Will the sticker be available to those of us that built the kit?

 

[emotorwerks]

I'm really happy with my Juicebox basic kit. I had some problems at the outset with trips and it turned out my new 40 amp breaker was defective. As part of the troubleshooting, with which emotorwerks was very helpful, the importance of keeping the wires through the GFI current sensor parallel was very evident and I posted a comment earlier, as a juicebox building tip, to shrink wrap the two wires together perfectly parallel during assembly.

As I understand emotorwerks is getting, or has already gotten, UL approval for the juicebox. Will the sticker be available to those of us that built the kit?

Good to hear, Ted! Yes, eMotorWerks is in the process of obtaining UL certification for JuiceBox. I don't believe that this certificate will be retroactive. In part because some of the design elements have changed, and UL requires re-certificiation in similar situations. One thing we are very actively considering is an attractive upgrade path for early adopters.

 

[Tomasz]

I know about 120V. I've tried it myself as I have 20A outlet at work and wanted to see how fast I can charge it on 120V. Right now I'm able to fully charge it on L1 within 10h.

Great to hear! That's a neat trick, isn't it?

It definitely is a big help for all of us having access to 20Amp outlets so popular in office buildings.

What I have found interesting is that i3 is inconsistent in drawn power, depending on what pilot is set to it draws between 2 and 4 Amps less than pilot is indicating with the exception of case when settings between 16 and 18A result in exactly the same draw. On the other hand when you bump pilot to 20 or more it draws almost exactly what it's told to. Like there was a logic in the code thinking 'well, pilot is below 20A, we are on L1, lest limit the current' and 'hey, pilot is 20A or more, let's have some fun!'.

 

[jadnashuanh]

Keep in mind that on a 20A circuit in the USA, you should not try to use more than 16A to abide by the electrical codes (80% rule) for a continuous use device. Shorter term uses can use more power, but the wiring is not designed for continuous use at the stated limits. IOW, you'll likely overheat the receptacle if you tried to draw 20A from it continuously for hours.

 

[Tomasz]

Keep in mind that on a 20A circuit in the USA, you should not try to use more than 16A to abide by the electrical codes (80% rule) for a continuous use device. Shorter term uses can use more power, but the wiring is not designed for continuous use at the stated limits. IOW, you'll likely overheat the receptacle if you tried to draw 20A from it continuously for hours.

Yes, but when your EVSE is set to 20A the i3 will draw 15A. Not great, but much better than factory trickle charger.

 

[jadnashuanh]

Yes, but when your EVSE is set to 20A the i3 will draw 15A. Not great, but much better than factory trickle charger.

Is that on 120 or 240vac? It very well may be limited on 120vac (level 1). In other markets, the KLE is optional, FWIW. Don't think that's part of the issue, but it could be. It may only work with one recharging unit when 120vac is present, and utilizes both of them when you go to level 2. Each has about the same capacity (thus the 15A), and if it is only utilizing one...or, it may require some threshold of incoming current to enable the KLE, otherwise, it funnels all of it into the other unit (used for regen, which is why it is always there on all regions).

 

[emotorwerks]

Yes, but when your EVSE is set to 20A the i3 will draw 15A. Not great, but much better than factory trickle charger.

Is that on 120 or 240vac? It very well may be limited on 120vac (level 1). In other markets, the KLE is optional, FWIW. Don't think that's part of the issue, but it could be. It may only work with one recharging unit when 120vac is present, and utilizes both of them when you go to level 2. Each has about the same capacity (thus the 15A), and if it is only utilizing one...or, it may require some threshold of incoming current to enable the KLE, otherwise, it funnels all of it into the other unit (used for regen, which is why it is always there on all regions).

On the photo below is an i3 drawing 22.5A from a 120V power source. We did not push it higher, but it appears that it could go up to 30A. Similar behavior was observed and validated with the LEAF. That said, it's possible that BMW has changed or will change this characteristic in a future firmware update. They reportedly revised the design of their KLE and have performed some software modifications as well.

 

[i3MK]

With the leaf, an engineer managed to figure out how to "unlock" the factory supplied trickle charger EVSE that comes with the car to take higher Amperes. Can the same be done with the BMW supplied trickle charger/EVSE? See evseupgrade.com

it would do away with the need to buy yet another piece of accessory!

20amp or more would be useful for emergency situations to prevent getting stranded when public chargers fail!

 

[jadnashuanh]

All J1772 EVSE's output a PWM square wave to announce how much power that they can provide. I'm sure that that is a factory calibration IN the EVSE and could be tweaked. But, consider that the components inside of the thing (relays, contactors, power switching devices, wiring, cord, etc.) may not be designed for higher currents. It may not be that the device couldn't be tampered with to indicate more power was available, it's that the life of the components may not be reliable once you've done that. As to the i3, up to its design capabilities, IT knows how much power it can accept with any single input, and I doubt IT would be damaged because it may not ask for all of the power that is announced to be available. This is why you can connect the i3 (or any compliant J1772 device) to any EVSE, and it will adjust for the device's output, and use up to the max either the car can take, or the device announces (or the user imposed limit set within the i3).

In the USA, you also have to abide by building codes, and a device like an EVSE with potentially extended run times, should abide by the 80% rule - the load imposed should never be more than 80% of the circuit design. SO, on say a 20A circuit, NGT 16A should be used, or it would no longer meet code.

 

[i3MK]

All J1772 EVSE's output a PWM square wave to announce how much power that they can provide. I'm sure that that is a factory calibration IN the EVSE and could be tweaked. But, consider that the components inside of the thing (relays, contactors, power switching devices, wiring, cord, etc.) may not be designed for higher currents. It may not be that the device couldn't be tampered with to indicate more power was available, it's that the life of the components may not be reliable once you've done that. As to the i3, up to its design capabilities, IT knows how much power it can accept with any single input, and I doubt IT would be damaged because it may not ask for all of the power that is announced to be available. This is why you can connect the i3 (or any compliant J1772 device) to any EVSE, and it will adjust for the device's output, and use up to the max either the car can take, or the device announces (or the user imposed limit set within the i3).

In the USA, you also have to abide by building codes, and a device like an EVSE with potentially extended run times, should abide by the 80% rule - the load imposed should never be more than 80% of the circuit design. SO, on say a 20A circuit, NGT 16A should be used, or it would no longer meet code.

Thanks for the input, (truly), but it's not relevant since this i3 is an EU variant with IEC62196-2 rather than j1772. But again, thank you.

 

[Tomasz]

In the USA, you also have to abide by building codes, and a device like an EVSE with potentially extended run times, should abide by the 80% rule - the load imposed should never be more than 80% of the circuit design. SO, on say a 20A circuit, NGT 16A should be used, or it would no longer meet code.

Sure, but 16A beats 12A any day.

And there is plenty 20A outlets out there.

 

[BrianStanier]

Thanks for the input, (truly), but it's not relevant since this i3 is an EU variant with IEC62196-2 rather than j1772. But again, thank you.

AFAIK the protocols are the same, only the plug is different.

 

[jadnashuanh]

Thanks for the input, (truly), but it's not relevant since this i3 is an EU variant with IEC62196-2 rather than j1772. But again, thank you.

Functionally, both systems are identical except for the plug. IOW, the signaling works exactly the same way.