Can Blink EVSE supply enough juice to BMW ActiveE charger?

As far as I understand the ActiveE has a 7+ kW onboard charger. Can my Blink unit be used to charge the ActiveE at that level? BMW says charge time is 4-5 hrs on 240v/32A circuit. The Blink is rated at 30A, so seems like the answer to this question is no and charging will happen at the 16A level taking twice as long?

Valdemar said:

As far as I understand the ActiveE has a 7+ kW onboard charger. Can my Blink unit be used to charge the ActiveE at that level? BMW says charge time is 4-5 hrs on 240v/32A circuit. The Blink is rated at 30A, so seems like the answer to this question is no and charging will happen at the 16A level taking twice as long?

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The Blink is rated at 7.2kW (240v * 30a).

That's all the ActiveE needs, per BMW.

Thanks, I'm finding different numbers for the ActiveE chargers, there are references to 6.6 and 7.7 kW, the BMW site is not very helpful. If it is indeed 7.7 it would be over the rated Blink capacity.

I don't know for sure if they are compatible, but if everything works as it should, the pilot signal from the blink should tell the BMW charger the maximum "allowed" charge rate to pull. So, for instance if the BMW was capable of pulling 32A, but the EVSE was only configured to allow 24A, then the car's charger would reduce power consumption to 24A to suit the EVSE (and probably wiring / breaker behind it.)

There is very little risk you could overload something.

What is all this talk about the BMW ActiveE needing 32 amps to charge anyway? Are they suggesting the vehicle will not charge at 20 amps, 16 amps, 12 amps? I highly doubt it. I suspect BMW just wants those who lease the car to have a 32 amp evse and 40 amp service to meet user expectations of charge time.

Spies said:

What is all this talk about the BMW ActiveE needing 32 amps to charge anyway? Are they suggesting the vehicle will not charge at 20 amps, 16 amps, 12 amps? I highly doubt it. I suspect BMW just wants those who lease the car to have a 32 amp evse and 40 amp service to meet user expectations of charge time.

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Is there a 32 amp home evse? AV is the official EVSE supplier for BMW, their home charger is rated at 30A I've just checked.

TEG said:

I don't know for sure if they are compatible, but if everything works as it should, the pilot signal from the blink should tell the BMW charger the maximum "allowed" charge rate to pull. So, for instance if the BMW was capable of pulling 32A, but the EVSE was only configured to allow 24A, then the car's charger would reduce power consumption to 24A to suit the EVSE (and probably wiring / breaker behind it.)

There is very little risk you could overload something.

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I understand there is protection against overload, but I would certainly prefer to charge at max speed that the onboard charger allows me. I can only see references to charge times on 16A or 32A circuits for ActiveE. Does it mean there is no 24A or 20A mode? I don't know. But if there is none then you'd have to charge at 16A and it will take a long time to charge the 32kWh battery.

Sometimes you get similar capabilities stated different ways and so the results are confusing.

In US electrical code there is an "80%" rule saying don't draw continuous current more than 80% of the breaker / circuit capacity.

So a 40A circuit & breaker is needed for a device that can draw 32A.
A 30A circuit & breaker is needed for a device that can draw 24A.
(For the 2011 & 2012 LEAF, a 20A breaker is needed when using 16A.)

Many commercial locations are 208V, but many home locations are 240V.
So when you look at total kW used by charger, the voltage comes into play not just the amperage.

http://www.blinknetwork.com/file/296/OM0001_L2_R_WMv1.8.pdf" onclick="window.open(this.href);return false;

...blink EVSE’s factory default current setting is 30 amps...

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So, for typical home use you have a 40A breaker, 32A continuous capable circuit, but the blink lowers it to 30A (probably due to the rating of the J1772 plug.) 30A*240V=7.2kW

LEAF currently has a "3.3kW" charger, but will reportedly offer a "6.6kW" in future? Why 6.6kW, not 7.2kW? Not sure, but 208V@32A=6.6kW.

In any case, if the EVSE is 30A or 32A, and the car's charger is 6.6kW or 7.2kW they should be able to "negotiate" the highest common denominator and charge at the max allowed. That is assuming 240V home power. If you have 208V commercial power, not sure if the amperage will be higher due to lower voltage, or if you will be stuck charging at a slightly slower rate.

I'm a past EE major so I understand the technicalities, however I'm not familiar with the J1772 protocol. To rephrase, my question is what that highest common denominator will be when using Blink, whose output current rated at 30A, for charging the ActiveE on a 40A circuit?

http://www.plugincars.com/first-drive-bmw-activee-electric-coupe-108477.html" onclick="window.open(this.href);return false;

...BMW partnered with AeroVironment to provide home charging equipment. The car will charge at 32 amps, and a robust 7.7 kW...

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So, with a 40A breaker, a 32A capable EVSE, and 240V home service you could do 7.7kW charging.
But many EVSEs are only willing to let you pull 30A, so they would limit charging to 7.2kW.

At public/commercial locations you might find either:
208V at 32A for 6.6kW.
or
208V at 30A for 6.2kW.

Valdemar said:

I'm a past EE major so I understand the technicalities, however I'm not familiar with the J1772 protocol. To rephrase, my question is what that highest common denominator will be when using Blink, whose output current rated at 30A, for charging the ActiveE on a 40A circuit?

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7.2kW for home 240V use.
6.2kW for commercial 208V use.

Thanks, 7.2kW should be pretty quick, compared to current Leaf L2 charging anyway.

It wil charge at many rates, that is what a pilot signal is for. If you put a 3.8kw evse on it it will charge at that rate.

Understood, probably I didn't express the question clearly, but I was interested in the theoretical maximum when using the Blink on a 240V 40A line with ActiveE. One would hope that ActiveE supports additional levels in between 16A and 32A, because if not then then the highest safest number will be 16 A. One ActiveE owner reported he could only get ~3kW charging with his setup, could be a EVSE configuration issue: http://activeemobility.blogspot.com/2012/01/bmw-activee-dosent-disappoint.html" onclick="window.open(this.href);return false; .

Keep in mind 3.3, 6.6, 7.2 is generaly the power to the battery not the input power needed to drive the charger.
I think the 3.3 kW Leaf draws about 3.8 kW

Valdemar said:

Understood, probably I didn't express the question clearly, but I was interested in the theoretical maximum when using the Blink on a 240V 40A line with ActiveE. One would hope that ActiveE supports additional levels in between 16A and 32A, because if not then then the highest safest number will be 16 A. One ActiveE owner reported he could only get ~3kW charging with his setup, could be a EVSE configuration issue: http://activeemobility.blogspot.com/2012/01/bmw-activee-dosent-disappoint.html" onclick="window.open(this.href);return false; .

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The max is what the Blink is rated to output and what the BMW chooses to draw up to that max rating. If the BMW charger can draw 50kw it will only pull the max the Blink is rated to supply. If the BMW needs 1kw that is what it will draw. That is how a EVSE pilot signal is designed to work.

EVDRIVER said:

Valdemar said:

Understood, probably I didn't express the question clearly, but I was interested in the theoretical maximum when using the Blink on a 240V 40A line with ActiveE. One would hope that ActiveE supports additional levels in between 16A and 32A, because if not then then the highest safest number will be 16 A. One ActiveE owner reported he could only get ~3kW charging with his setup, could be a EVSE configuration issue: http://activeemobility.blogspot.com/2012/01/bmw-activee-dosent-disappoint.html" onclick="window.open(this.href);return false; .

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The max is what the Blink is rated to output and what the BMW chooses to draw up to that max rating. If the BMW charger can draw 50kw it will only pull the max the Blink is rated to supply. If the BMW needs 1kw that is what it will draw. That is how a EVSE pilot signal is designed to work.

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Right, it is the car that controls how much power it draws from EVSE and the current should not exceed the max advertised by the EVSE. How it is implemented in the car I don't know but I'm pretty sure the current levels it selects are discrete , perhaps it controls the number of battery cells that are charging in parallel. What if for some weird reason the car supported only 2 current levels? Say it can draw 32A max but the next step down is 16A. Then it will use 16A if the EVSE tells it it only can provide 30A max. Perfectly legal from the J1772 standard point of view and safe. My hope that ActiveE is more sophisticated than that and can utilize as much of a 30A EVSE as possible, even if the max current it can draw is 32A (from a more powerful EVSE).

No, the charging current level is NOT discrete, at least to a resolution of about .1KW. The J1772 pilot signal is analog. There is no control over the charging of the individual battery cells, except during a cell balancing operation. In the Leaf there are 96 cell pairs wired in series, with the 2 cells of each pair in parallel, so every cell pair gets the same number of coulombs of charge. The battery management system will taper down the charge rate current as the state of charge approaches 100%. On the Leaf at L2, this taper starts at about 95% during the last 30 minutes or so of charge. The 3.3kW L2 max net charge rate tapers down to about 1.7kW before the charge stops at 100%. With external L3 charging, the taper begins much earlier, from a much higher starting rate, well before 70%. The L3 communication between the external QC charger and the car is more sophisticated, with its own dedicated 2-way digital CAN bus.

tbleakne said:

No, the charging current level is NOT discrete, at least to a resolution of about .1KW. The J1772 pilot signal is analog. There is no control over the charging of the individual battery cells, except during a cell balancing operation. In the Leaf there are 96 cell pairs wired in series, with the 2 cells of each pair in parallel, so every cell pair gets the same number of coulombs of charge. The battery management system will taper down the charge rate current as the state of charge approaches 100%. On the Leaf at L2, this taper starts at about 95% during the last 30 minutes or so of charge. The 3.3kW L2 max net charge rate tapers down to about 1.7kW before the charge stops at 100%. With external L3 charging, the taper begins much earlier, from a much higher starting rate, well before 70%. The L3 communication between the external QC charger and the car is more sophisticated, with its own dedicated 2-way digital CAN bus.

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Actually, the LEAF does not taper off at 95% but you are sort of close on that point.

The car will pull the maximum it wants to up to the limit imposed by the EVSE's pilot signal. If the EVSE is putting out a 24A signal (in the case of the Blink), the car will pull up to 24A and no more. If it is capable of more then this would slightly reduce the charging speed. It would not drop to 16a though!

Also: I have yet to see my Leaf charge to over 95% SOC EVER! This is the true SOC reported by the Battery ECU, and not what's shown on the dash or in carwings, that number is "faked".

-Phil