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      08-13-2014, 02:48 PM   #1
DDF200
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i3 Charging

I'm confused about the charging system on the i3, specifically the dashboard/software controls.

I've set Level 1/2 at maximum. I have a 50 amp line, 40 amp EVSE from which the Tesla charges flawlessly.

I'm struggling to understand:

1) Charge time windows. I just want to set a charging window of 12 midnight to 5am, regardless of all other variables. Can it be done?

2) How do I know what my charging level is when plugged in? I'm specifically looking for an indicator showing that I'm drawing at 30+ amps (or up to 7+ kilowatts). Does the feature exist? All I can find is a graphic that says I'm charging. Not so helpful.

3) DC Fast: I plugged into our local DC Fast charger, but again, was not clear what the actual charge level was that I was experiencing. The DC Fast indicator icon did not appear, but there was charging occurring. Again, just not sure if it was Level 1 or 2 and if 2, the number of kilowatts I was at.

Am I missing something? Any help appreciated.
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      08-13-2014, 05:13 PM   #2
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The EVSE, technically speaking, is only a fancy on/off switch...regardless of how much power it may have available, the car will only ask for what it can handle - the actual charging circuits, at least for the ac, are IN the car (sort of like plugging your 1A phone charger into a 15A receptacle...it doesn't really matter, it's still only going to draw one amp). The i3 is designed to accept up to 30A ac on a level 2 (Europe rates it different, and there, they call the same thing a 32A unit).

But, no, the i3 does not have a user visible indication of how much current it is drawing from the EVSE. You can get a bit more info from the i3 remote app, though, but that requires something with either Android or iOS on it.

Now, the DC fast charger is a bit different, as it is feeding DC voltage in, which bypasses most of the ac-dc conversion (the charger) in the i3. The i3 is designed to accept up to 50Kw DC chargers...a bigger one will not charge it faster as the car restricts the draw to a max of 50Kw, and as it is monitoring the battery temperatures, it will slow that charge rate down (on both the ac and dc charging cycles) as they approach a certain level.

So, depending on how discharged the batteries are, and the EVSE you have, 5-hours would be sufficient most of the time, but keep in mind level 1/2 are 120vac/240vac, and not all EVSE's are created equal...it's possible that a level 2 unit could take longer than a level 1 unit, but I'm not sure why someone would build it! There are some that are very close to being the same, though.
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      08-13-2014, 09:30 PM   #3
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Quote:
Originally Posted by DDF200 View Post
I'm confused about the charging system on the i3, specifically the dashboard/software controls.

I've set Level 1/2 at maximum. I have a 50 amp line, 40 amp EVSE from which the Tesla charges flawlessly.

I'm struggling to understand:

1) Charge time windows. I just want to set a charging window of 12 midnight to 5am, regardless of all other variables. Can it be done?

2) How do I know what my charging level is when plugged in? I'm specifically looking for an indicator showing that I'm drawing at 30+ amps (or up to 7+ kilowatts). Does the feature exist? All I can find is a graphic that says I'm charging. Not so helpful.

3) DC Fast: I plugged into our local DC Fast charger, but again, was not clear what the actual charge level was that I was experiencing. The DC Fast indicator icon did not appear, but there was charging occurring. Again, just not sure if it was Level 1 or 2 and if 2, the number of kilowatts I was at.

Am I missing something? Any help appreciated.

I have the BMW level 2 charger in my garage. The i3 is limited at 7.4kW no matter what amperage you have coming into it. It charges from near empty to full in around 3 hours????maybe less. So from midnight to 5am should be no problem on a level 2 charger. User above was correct in explaining how the car has the charger on board and the evse just turns on and off the power. Just wanted to clarify what the i3 is limited to onboard. If it is sending 7.4kW, and the battery holds 19kwH, then it should only take 2.5 hours, but there are some losses with charging (the fans run to cool the charger and there are ac/DC conversion losses), so it ends up being a little over 3 hours. You won't be completely dead every night probably, so like me, you'll only charge for an hour or two depending on the starting charge level of the car.


Regarding DC fast, user above has it mostly correct. The DC fast chargers are combo chargers, so they charge with DC as well as supply AC 240V to the onboard charger. They say 80% full in 20-30 minutes.

To answer your main question, there is nothing on the car to tell you the rate of charging. It is dependent on the EVSE and it'll only tell you the kW draw. I've found the BMW wall charger charges much faster than the BMW dealership chargers. They use charge point chargers and I don't believe they have the full amperage run to them.

Hopefully that helps. In hot climates, battery life is worse. Preconditioning can add 10-15 miles to my range in the morning. Pretty awesome if I have it set, but not so awesome if my car is parked in 106 degree weather for 8 hours. Range drops quite a bit. If you have access to plug into even a 120V 15amp where your car is parked during the day, you will be able to precondition and extend your range significantly. Even if the 120v doesn't charge so much.
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      08-13-2014, 11:34 PM   #4
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This is helpful, thanks for the details. Excellent to understand the value of preconditioning. I'll pay more attention to that.


2) It's a huge miss not showing the charge rate. I have no way to understand if the input is what I think it should be, whether at home or a public charging station.

3) For DC Fast, does the indicator light appear regardless of the rate or state of charge? It did not appear when I was plugged in.

Thanks!
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      08-14-2014, 04:30 PM   #5
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7.4 or 7.7KW? 30 or 32 A?

Quote:
Originally Posted by Rapcat View Post
I have the BMW level 2 charger in my garage. The i3 is limited at 7.4kW no matter what amperage you have coming into it. It charges from near empty to full in around 3 hours????maybe less. So from midnight to 5am should be no problem on a level 2 charger. User above was correct in explaining how the car has the charger on board and the evse just turns on and off the power. Just wanted to clarify what the i3 is limited to onboard. If it is sending 7.4kW, and the battery holds 19kwH, then it should only take 2.5 hours, but there are some losses with charging (the fans run to cool the charger and there are ac/DC conversion losses), so it ends up being a little over 3 hours. You won't be completely dead every night probably, so like me, you'll only charge for an hour or two depending on the starting charge level of the car.


Regarding DC fast, user above has it mostly correct. The DC fast chargers are combo chargers, so they charge with DC as well as supply AC 240V to the onboard charger. They say 80% full in 20-30 minutes.

To answer your main question, there is nothing on the car to tell you the rate of charging. It is dependent on the EVSE and it'll only tell you the kW draw. I've found the BMW wall charger charges much faster than the BMW dealership chargers. They use charge point chargers and I don't believe they have the full amperage run to them.

Hopefully that helps. In hot climates, battery life is worse. Preconditioning can add 10-15 miles to my range in the morning. Pretty awesome if I have it set, but not so awesome if my car is parked in 106 degree weather for 8 hours. Range drops quite a bit. If you have access to plug into even a 120V 15amp where your car is parked during the day, you will be able to precondition and extend your range significantly. Even if the 120v doesn't charge so much.
Hi Rapcat et al-

I'm trying to decide which EVSE to install for my i3 that arrives next week. I was planning to do the Schneider 30 amp, 7.2kw -- but then my electrician suggested I should move up to the Leviton one that is 32 amp, 7.7 kw. He says the i3 charger can go up to 7.7kw (not 7.4) and so I would get a significantly (though not extremely) faster charge through the Leviton unit than through the Schneider unit. Of course the Leviton unit is more expensive (by about $300) than the Schneider one.

I would greatly appreciate any advice you might have to offer on this. Thanks!
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      08-15-2014, 02:07 AM   #6
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Quote:
Originally Posted by tiburonh View Post
Hi Rapcat et al-

I'm trying to decide which EVSE to install for my i3 that arrives next week. I was planning to do the Schneider 30 amp, 7.2kw -- but then my electrician suggested I should move up to the Leviton one that is 32 amp, 7.7 kw. He says the i3 charger can go up to 7.7kw (not 7.4) and so I would get a significantly (though not extremely) faster charge through the Leviton unit than through the Schneider unit. Of course the Leviton unit is more expensive (by about $300) than the Schneider one.

I would greatly appreciate any advice you might have to offer on this. Thanks!
I don't have direct experience with these units, but I did spend four years living off the batteries in my boat. The acceptance curve of the batteries is a big factor in getting a full charge. Once the state of charge (SOC) reaches about 80%, the charger will cut back the current to the batteries irrespective of supply (lead acid batteries on the boat would cut back much earlier). The last 20% can easily take 40% of the total charge time.

In practice there is no meaningful difference between a 7.2kW and 7.7kW charger. In the race to get to 80%, the 7.7 might win by 5min. Save your money.
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      08-15-2014, 09:31 PM   #7
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I do not think there is a real, practical difference between a unit capable of 30A or 32A...there might be slightly less heat produced with the 30A unit, so it might stay at a higher rate slightly longer, and you'd end up with the same end result in full charge. The max charge rate the i3 can handle is 7.4Kw. 30A*240vac = 7200W. Your supply voltage may vary slightly from that nominal value of 240vac, and either above or below will affect the charge rate as well. As an example, a unit capable of 32A at 240vac, would only provide 7.04Kw at 220vac.

The latest i3 software changes the charging logic based on the temperature, and if (when) you have that installed, could limit the charge rate by as much as 30%. This is related to an issue with the onboard charge unit (KLE) and they should have a resolution for this (they say) either late this year or early next. The s/w mod should keep the KLE from failing to charge at all in the interim.

Last edited by jadnashuanh; 08-15-2014 at 09:37 PM..
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      08-16-2014, 01:06 AM   #8
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Quote:
Originally Posted by jadnashuanh View Post
I do not think there is a real, practical difference between a unit capable of 30A or 32A...there might be slightly less heat produced with the 30A unit, so it might stay at a higher rate slightly longer, and you'd end up with the same end result in full charge. The max charge rate the i3 can handle is 7.4Kw. 30A*240vac = 7200W. Your supply voltage may vary slightly from that nominal value of 240vac, and either above or below will affect the charge rate as well. As an example, a unit capable of 32A at 240vac, would only provide 7.04Kw at 220vac.

The latest i3 software changes the charging logic based on the temperature, and if (when) you have that installed, could limit the charge rate by as much as 30%. This is related to an issue with the onboard charge unit (KLE) and they should have a resolution for this (they say) either late this year or early next. The s/w mod should keep the KLE from failing to charge at all in the interim.
Thanks for your, as always, well informed advice!
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      09-01-2014, 08:57 AM   #9
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Quote:
Originally Posted by tiburonh View Post
I'm trying to decide which EVSE to install for my i3 that arrives next week. I was planning to do the Schneider 30 amp, 7.2kw -- but then my electrician suggested I should move up to the Leviton one that is 32 amp, 7.7 kw. He says the i3 charger can go up to 7.7kw (not 7.4) and so I would get a significantly (though not extremely) faster charge through the Leviton unit than through the Schneider unit. Of course the Leviton unit is more expensive (by about $300) than the Schneider one.

I would greatly appreciate any advice you might have to offer on this. Thanks!
Both the unit marketed as 30 amp, and the one marketed as 32 amp most likely put out equivalent max wattage. The J1772 protocol negotiates max amperage using a PWM signal in something of a step manner. Both units use the 50% PWM signal level to trigger the same max power. In the US (SAE) the definition of the "ampacity" (ampere capacity) is split for continuous and short term operation, while the IEC has included the same ampere steps with only one nominal definition. Hence a manufacturer may chose to market his device as either 30 amp (SAE) or 32 amp (IEC):

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      09-01-2014, 01:57 PM   #10
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All very confusing. If it helps anyone, I had the standard BMW i charger installed last week in the UK, and it is a 32 amp unit.

But the installer did say they down-rate the current in the unit if the electricity supply cannot safely deliver 32 amps. They test for that before installing. Mine was ok, after they took a direct feed from the mains at the meter.

However, bear in mind that we do run at 220/240V here, not 120V as in the USA.
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      09-01-2014, 06:48 PM   #11
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All level 2 EVSE are 208-240vac, and to get the max ac charge rate, you require one of these, regardless of where you live. In NA, the supplied EVSE is a level 1 device (runs on 120vac), whereas those in Europe, since their normal supplies are 240vac, they get a (still small) level 2 device.

Bottom line, if you're using acv, you want a unit that can provide 30A or more at the 208/240vac input (the car won't use more, but, you may get a new car that could - it won't hurt the i3 one bit). I do not see a DC fast charger becoming available for the typical homeowner in most markets, partly because of their cost, and second, because of the required input power requirements. The i3 can use up to a 50Kw device, and if using 240vac as the input, that's over 200A...much more than most homes need to run everything, so adding in one of those, would be a major upgrade. IF you have higher voltage available, it's still expensive, but more likely to be possible.
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      01-15-2020, 03:47 PM   #12
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Quick question guys - I ordered a Juice 32 and I got a email that I might receive a 40 amp unit instead. Am I correct in assuming the I3's onboard charger will limit the current to 30 amps regardless if the wall unit was rated for 40 amps.

Also is there a Wi-Fi menu on the juice where I could set the max current on the wall unit to 20 or 10 amps to reduce my charge rate? or is the juice just a 220 plug?

Thanks Mike
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      01-16-2020, 02:29 PM   #13
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Quote:
Originally Posted by Idleup View Post
Quick question guys - I ordered a Juice 32 and I got a email that I might receive a 40 amp unit instead. Am I correct in assuming the I3's onboard charger will limit the current to 30 amps regardless if the wall unit was rated for 40 amps.

Also is there a Wi-Fi menu on the juice where I could set the max current on the wall unit to 20 or 10 amps to reduce my charge rate? or is the juice just a 220 plug?

Thanks Mike
The i3 will only charge at the rate it can accept power. Always better to buy a bigger charger that you can use later on. 40 amp on a 50 amp breaker is what I have.

Last edited by TimeFor; 01-16-2020 at 02:39 PM..
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      03-19-2021, 08:34 AM   #14
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Is the 12 volt battery charged or maintained also when the car is plugged into the charging port?
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      03-21-2021, 03:30 PM   #15
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The charging display shows a moving bar that sweeps through each 1/4-charge segment in one second. By counting the number of seconds between 1/2% increases in state of charge you can do a little math and calculate the charge rate. You can pre-compute the values and use a look-up table.
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File Type: pdf ChargeSecondsToRate.pdf (20.6 KB, 259 views)

Last edited by JohnWasser; 03-22-2021 at 08:20 AM.. Reason: Converyed table to PDF
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      04-05-2021, 09:20 PM   #16
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Quote:
Originally Posted by Coastali8 View Post
Is the 12 volt battery charged or maintained also when the car is plugged into the charging port?
Yes, there is a DC-DC power supply in the i3 that will top up the 12vdc battery while plugged in AND charging, or when the vehicle is in the READY state. On a long term sitting where the vehicle is not being used, it may not turn on the power supply to keep the 12vdc battery up unless put back into the ready state periodically since the LiOn batteries have a very low self-discharge rate, so they may not call for charging often enough to keep the 12vdc battery topped up. This is not generally an issue if you drive the vehicle regularly.

ALl of the computers are run from the 12vdc supply, so if that battery dies, your vehicle becomes a big brick even if the main high voltage battery is full. There is a phantom 12vdc charging circuit that MIGHT recharge the battery when plugged in, but it is a very small supply, and if the battery is too far gone, probably won't get you going again without changing the battery, or if you're lucky, charging it directly with an external 12vdc charger.
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