gokeeffe
Posts: 1
Joined: Wed Sep 11, 2019 3:40 am

Supported Charging speeds 94ah

Wed Sep 11, 2019 3:52 am

I'm a new i3 94ah owner (previous Leaf owner) - not REX.
My query is around the supported charging speeds for the 94ah model.
Most of the on-street chargers are of the mode 2 fast charge, i.e. 22kw but my i3 doesn't seem to drawing the charge near that speed.
I do have a 3 phase 22kw cable connected but charging seems slower perhaps 7kw or 11kw - unsure how to tell.
My question is what charging speeds does the i3 94 ah support (mine is 2017 model)
also, how can I tell the rate of charge?

Thx
G

derekgates
Posts: 31
Joined: Sun May 12, 2019 5:10 pm

Re: Supported Charging speeds 94ah

Wed Sep 11, 2019 7:08 am

gokeeffe wrote:
Wed Sep 11, 2019 3:52 am
I'm a new i3 94ah owner (previous Leaf owner) - not REX.
My query is around the supported charging speeds for the 94ah model.
Most of the on-street chargers are of the mode 2 fast charge, i.e. 22kw but my i3 doesn't seem to drawing the charge near that speed.
I do have a 3 phase 22kw cable connected but charging seems slower perhaps 7kw or 11kw - unsure how to tell.
My question is what charging speeds does the i3 94 ah support (mine is 2017 model)
also, how can I tell the rate of charge?

Thx
G

Great questions. I find the i3 charging 'displays' incredibly lacking for such an advanced and customizable car. I use my Level 2 'charger' app to know the kWh charge rate of my i3. If this is unavailable for you, look at the estimated finish time for charging shown on the i3 display. At ~7kWh my i3 takes 4 hours to charge fully. That is the max charging; ~30.2A.

Be sure to set your charge rate in the iDrive settings of your i3. You want maximum charge rate set.

robthebold
Posts: 93
Joined: Sat May 11, 2019 5:09 pm

Re: Supported Charging speeds 94ah

Wed Sep 11, 2019 7:30 am

When I charge at a public level 2 station, it's usually around 6.7-6.9kW. The chargers I use tell me (on the display) the rated power -- which in most cases is 7.2kW -- and on completion the average power and total energy delivered. I suppose if yours don't have a display, you could time how long you charge and compute the rate by hand looking at your bill or statement if that's provided. My network also sends me a text when charging completes and when I unplug, so I have the end time there as well.

alohart
Posts: 1920
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Supported Charging speeds 94ah

Wed Sep 11, 2019 10:50 am

gokeeffe wrote:
Wed Sep 11, 2019 3:52 am
.My query is around the supported charging speeds for the 94ah model.
Most of the on-street chargers are of the mode 2 fast charge, i.e. 22kw but my i3 doesn't seem to drawing the charge near that speed.
No i3 has supported 22 kW 3-phase AC charging. 11 kW is the maximum 3-phase AC charging power, and 7.2 kW is the maximum single-phase AC charging power. However, not all i3's support 3-phase charging, and in some markets, 3.6 kW is the standard maximum charging power. If your i3 is a European model, it should charge at at least 7.2 kW.

Maybe use a BMW VIN decoder Website to determine what charging equipment your i3 has.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

jadnashuanh
Posts: 4788
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Supported Charging speeds 94ah

Wed Sep 11, 2019 5:37 pm

For ACV inputs, the i3 requires two modules to charge at its maximum rate. In some markets, the second module was optional as was/is? the DCV CCS input. The CCS input is capable of a maximum of 50Kw.

The actual power supplied to the car depends on the current voltage related to the EVSE's signal indicating maximum current. The EVSE routine announces how many amps it has. How much power is delivered, though is a combination of not only sourcing those amps, but the supply voltage as well. Say the EVSE says it can provide 30A, but the voltage was 208vac (a common commercial voltage in the USA)...30A*208vac=6,240Watts. Take that exact same EVSE, but connect it to a supply with 240vac*30A=7,200 watts. A 30A unit in many Eurozone locations might have 220vac*30A=6600 watts. So, also consider that depending on the battery temperature during charging, the car may not charge at the full rate, and as it approaches full, it will drop the charging rate down, it will depend on more than just the EVSE to determine how much power is supplied to the i3. Note that the DC-AC conversion is not perfect, so you'll put more power into the car than you can get out especially when you consider there may be some heating or cooling required in the process (depending on where it started).

Bottom line, without knowing the supply voltage AND the maximum current rating of the EVSE, you can't tell how much power it will deliver to the battery charging system.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

eNate
Posts: 281
Joined: Mon Sep 09, 2019 5:33 pm

Re: Supported Charging speeds 94ah

Mon Sep 16, 2019 1:29 pm

What about on the opposite end, at 120v Level 1?

I see Clipper Creek advertising a 20 Amp Level 1 charger. Presuming I have a 20A 120V circuit at work to connect to, will the i3 take advantage of this higher current? I believe the included Level 1 charger is only good for 13A?

As a new owner, my intention is to charge primarily at work for 8 hours per day, and the remainder at home. The stock charger is feeding me about 5 miles of range per hour, or about 40 miles over an 8 hour window. A 20A current, if compatible, could theoretically increase this to 60 miles during that same period of time.
2 0 1 7   B M W   i 3   9 4 A h   B E V  O a k l a n d
 Wokeby Trunk Extension | Duosida 16A L1 EVSE
 SeaSucker Monkey Bar Roof Rack

jadnashuanh
Posts: 4788
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Supported Charging speeds 94ah

Mon Sep 16, 2019 4:49 pm

To abide by the electrical code, since the device is considered a constant or extended use device, any EVSE's supply will be 125% of what actually can be used. (It's officially called the 80% rule.) So, 80% of 20A would mean the max that device could supply continuously would be 16A. 125% of 16A = the 20A circuit max.

The 12A is 80% of a 15A circuit. Your charging speed would go up by about 1/3'rd going from a 12A unit to a 16A one. Make sure that the receptacle's contacts still have some resilience to them...it should take some force to insert and remove the plug. If it slips in, it will create enough resistance and likely overheat, potentially ruining your plug.

Note that 120vac devices lose more in the conversion needed for charging than 240vac inputs. So, if you're paying for it, to recharge the same battery, you'll use more energy with a 120vac device than you will with a 240vac unit.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

eNate
Posts: 281
Joined: Mon Sep 09, 2019 5:33 pm

Re: Supported Charging speeds 94ah

Fri Sep 20, 2019 9:05 pm

I not sure this will work. I found this (text copied below) in an online owners manual circa 2015 (mine is a 2017). But it would seem to indicate that because US models are supplied with a 120V / 15A charger, my charge rates are locked in by the vehicle, I'm assuming to Max: 12A / Reduced: 9A / Low: 6A.

So question being, if I did locate a 120V / 20A NEMA 5-20 charger (yes, in reality 16A), would my i3 even be able to make use of the increased 30% capacity? Or is it capped at a max of 12A?

Again, I'm seeking to proceed this direction due to the four dedicated 20A outlets I have available at work where I can charge for no cost, which means less charging at home where I'm paying the bill.

Additionally, if I did find a way to code the car for the next higher rate bracket -- 15A / 11.25A / 7.5A -- and then found myself in a place where I had to use the original charger and plug into a 15A receptacle, if left unchanged to MAX, would the car try to pull this much current from the charger? I'm not sure I'd trust myself to reduce the charge level to "Reduced / 11.25A" and risk frying a circuit or causing a fire.

Free charging sure is hard to pass up!

Quoted from the Owners Manual:

Depending on the country-specific version,
one of four ampere ratings is printed on the
Level 1 charging cable. This ampere rating is
the limit which must be adhered to for the vehi‐
cle if the charge current is set to "Maximum".
According to the market-specific version, the
charge current strength changes differently if
the setting "Reduced" or "Low" is selected.

"Maximum" "Reduced" "Low"
8 A 6 A 6 A
10 A 7.5 A 6 A
12 A 9 A 6 A
15 A 11.25 A 7.5 A
2 0 1 7   B M W   i 3   9 4 A h   B E V  O a k l a n d
 Wokeby Trunk Extension | Duosida 16A L1 EVSE
 SeaSucker Monkey Bar Roof Rack

jadnashuanh
Posts: 4788
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Supported Charging speeds 94ah

Sat Sep 21, 2019 1:08 pm

All i3's can utilize 240vac, level 2 charging.

The reason there's a way to limit the charging rate on those with 120vac circuits is to handle a shared circuit...i.e., say in the garage where the garage door opener is on the same circuit. If you let it charge at maximum, and then opened or closed the door, you might overload the circuit breaker. A 240vac circuit is typically a dedicated circuit to one thing, and thus, the charging rate isn't as big a factor (at least in the USA).

THere's a slight disconnect in the maximum rate. The EVSE sends out a signal indicating how many amps it has. There's nothing in that signal that says what voltage it is - the vehicle senses that. SO, as was discussed earlier, since the EVSE limits how many amps it has, and the car will honor that, it also won't draw more actual power than it knows it can handle. So, the car has a limit of 7400W in the USA on ACV inputs, but is responding to the maximum amps the EVSE says it has. If that were 120vac, that would be a different amount of power versus say 110, or 130, or 208, or 220, or 240. In my case, my typical power is 248vac, so at 30A*248v=7440W, or more than the car can accept...the car is the limit on one side and the EVSE is on the other. Think plugging in a 100W light bulb, even though a 15A circuit can provide 15*120=1800W, it works just fine when you only draw 100W from it. In the case of the i3, you can dial down that "100W" to say about 50W in the software so it might not pop if you also had a space heater on the same circuit.

So, yes, a larger EVSE could shorten your charging time. However that EVSE is powered, it should not use more than 80% of the available power. On a 15A circuit, that's 12A. On a 20A circuit, that's 16A. On a 40A circuit, that's 32A, and so on.

In a home, your limiting factors are the installed wiring and protection circuit then coupled with the EVSE you selected. Never install an EVSE that can provide more power than the wiring and circuit breaker is designed for. Note, some EVSE's can be adjusted internally to announce they have different amounts of power. One of those, as long as it didn't exceed the wiring, could be dialed up or down to suit your available infrastructure. The vehicle won't pull more than the max that is announced, in any case, and, if you sprung for a really large one, would not max it out.

Plug-in hybrids may not have as high a charging rate as the i3, plus, they tend to have a smaller battery, so it's not a big deal. When using ACV inputs, the limiting factor is the DC power supply in the car...it only draws some max. Just like the light bulb example, if the source has more, it won't hurt anything.

In some markets, the maximum ACV charging rate is 3700W. All vehicles in the US have two modules installed that bumps it up to 7400W. A few places have a different internal AC-DC power supply.

When using a CCS unit, you bypass the AC-DC power supply, and are feeding DCV directly into the batteries. That data communications scheme is a bit more complex as it controls the voltage coming out of the CCS unit. REgardless, though, the car won't pull more than what's available, and having more isn't an issue.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

eNate
Posts: 281
Joined: Mon Sep 09, 2019 5:33 pm

Re: Supported Charging speeds 94ah

Sat Sep 21, 2019 3:39 pm

Jim, yeah, I understand the rational behind the levels and the fundamentals behind how electricity is delivered, but that's not getting to my root question.

If I plug in the "20A charger" (nay 16A), it sounds like you believe the i3 *will* be able to make use of that extra current? Because the verbiage from the owner's manual seems to contradict that, except that it's written in laymen's language and not as a technical document, so I forgive BMW if they're a little off-point here..

I think the 100w bulb example is too simple for making a comparison here. After all, we're talking about electronic intermediaries both in the car and in the charger that are actively regulating current flow. I'm actually thinking back to the early days of USB when the ports were only capable of delivering 0.5A, but new USB devices were introduced that could easily outstrip supply and fry the computer's USB circuit, and sometimes the motherboard. Later iterations of the USB standard addressed this through a variety of techniques in an attempt to make the connections "smart" although none as advanced as what we're talking about with our EVSEs.

I'm going to chat with Clipper Creek and see if I can get me a unit to demo, although it appears they only sell this for hardwired installations, not ready for NEMA 5-20 connections.
2 0 1 7   B M W   i 3   9 4 A h   B E V  O a k l a n d
 Wokeby Trunk Extension | Duosida 16A L1 EVSE
 SeaSucker Monkey Bar Roof Rack

Return to “News and Main BMW i3 Forum Discussions”