Why the BMW i3-REx

Working on a more accurate cost per mile model, I ran to work and back:

5.4 kWh = 20 mi / 3.7 mi/kWh
$0.54 = 5.4 kWh * $0.10 / kWh (highest residential rate)
$0.027/mi = $0.54 / 20 mi


0.9% SOC/mi = (100.0%-82.0) / 20 miles

JuiceBox Pro 40A

$0.466 = 4.66 kWh * $0.10/kWh
$0.233/mi = $0.466 / 20 mi

1:06 hh:mm charge time



Idaho National Labs: Vehicle Testing - Light Duty - All | Advanced Vehicle Testing Activity

• $0.10-11/mi - Gen-3 Prius(*)
• $0.22-23/mi - BMW i3-REx(*)

* - includes fuel, insurance, and registration

Curious, their results are so different from mine.

We also have a Gen-3 Prius:

• $0.034/mi = $2.00/gal / 52 mi/gal

Today, our $0.0233-$0.027/mi, BMW i3-REx is cheaper per mile than our $0.034/mi Gen-3 Prius. However, a Gen-4 Prius has a chance of parity. I won't know until I get a chance to benchmark a rental, Level 2 ECO. However, I need to check calibrations, part of this exercise.

Bob Wilson

 

TVA has nice rates although I understand they are planning a rate increase.

Bob Wilson

 

I was working on how to add a plug-in port or outlet at work when I realized, there is no point. Now that I have a data recording, high-speed charger at home (see below,) it costs just under $0.60 per day for a round-trip, commute to work. Charging at work would only save $0.30 which isn’t hardly worth the trouble. Especially because there are four free chargers, two at Whole Foods, 3-4 miles away, and two at Bridge Street, 2 miles away, where I can eat lunch for between $5-15 and save nearly half of my commuting costs.



I did not buy the BMW i3-REx to become dependent on someone else for a plug or hose. I bought it for the freedom to go where I want and when I want. Now if an enlightened business would like my patronage ... well I do like free chargers.

Bob Wilson

 

A Facebook essay shared with my family:

July 11-12, we finished the last of the house wiring upgrades. The outer insulation of our 48 year old, utility service line had rotted off so adding the NEMA 14-50 (aka., RV park socket) required utility service rewiring too. For a little more, we went from 100A to 200A service with a 'transfer switch' for an emergency generator.

Level 1 (120VAC, 12-15A) charger

The BMW i3-REx comes with a 120VAC, 12A Level 1 charger. Initially we plugged into a kitchen wall outlet close to the driveway. We limited the current to 10A but accidental operation of the microwave or toaster would trip the 15A circuit breaker. But when sleeping, who is cooking?

Later, I bought the parts to make an adapter for the dryer socket, a NEMA 6-30 three-prong Y-socket. The adapter split it into two, independent, 15A circuits, using NEMA 5-15 (regular house plug) with ground fault safety. This meant we no longer ran an extension cord from the kitchen and let the Level 1 charger run at full, 12A. But it still took hours to top-off, charge the car after an ordinary day of driving. Still, with an occasional visit to the free, high capacity Level 2 chargers or using the range extender (REx) engine, no problem.

Level 2 (240VAC, 32-50A) charger

We bought a 'JuiceBox Pro 40' that comes with a NEMA 14-50 plug like those found at RV parks. But the BMW i3-REx limits AC charging to 32A. The Level 1 and Level 2 charging circuits, built into the car, set the charging rate. So I've actually 'overbuilt' the NEMA 14-50 circuit but that capacity is available for a future EV and reduces wiring losses.

I usually get home with about 80% battery level. The car fully charges in an hour and 15 minutes and a discharged battery should take 3-4 hours. I no longer need to visit the 'free', high capacity Level 2 chargers.

Cost EV vs. Gasoline

Our highest residential power rate is $0.10/kWh and my typical, workday driving takes just under 6kWh for ~20-25 miles or just under $0.60/day. I was looking at work-place charging but it would only save $0.30/day. Over a year, ~250 work days, saving $150. But eating lunch at free Level 2 charger does the something.

Our 2010 Prius gets 52 MPG in a similar commute and regular gas today is $1.88/gal. So 25 miles would be half a gallon or about $0.94/day. Prius parity occurs when gasoline reaches $1.20/gal. But the BMW i3-REx uses plus gasoline, $2.18/gal, at 44 MPG or about $1.35/day.

A new 2016 Prius was offered for $28.5k versus the $29.9k paid for the BMW i3-REx. But with the 16kW, natural gas generator, our BMW i3-REx runs on:
(1) TVA electricity (~$0.60/day)
(2) gasoline (~$1.35/day)
(3) natural gas generated electricity (~$1.08/day)​

Bob Wilson

 

First full month utility bill which arrived with the hot weather:

• $8.88 - access charge
• $129.30 - 1400 kWh @$0.092360
• $52.96 - 527 kWh @$0.100500
• $191.14 - total, 1927 kWh

July 2015, ~1600 kWh

About alternate taxes to replace gasoline tax: https://avt.inl.gov/sites/default/files/pdf/phev/PEVandPHEVeVMTforIAHD.pdf

• $34.73 - PHEVs
• $72.22 - BEVs

Seems like reasonable fees to me.

Bob Wilson

 

I understand there is a bill in Montgomery but I don't know the particulars. I was told by a guy at work who is building his own EV.

He introduced me to a lady at work who bought a Leaf a couple of weeks ago. Then another tenant came by when I was going to lunch asking questions about the BMW i3. So I'm thinking about making some 'Take One' flyers for the car.

Bob Wilson

 

Printing a couple of flyers to leave on the car:


I've been approached roughly every 1-2 weeks by strangers asking about the car. If I have time, we chat but sometimes I have things to do and informal chats don't always cover everything. The only thing missing, follow-up. So I'm thinking about referencing PriusChat.

Bob Wilson

 

Looking for something else, I stumbled across the YouTube that raised my interest in the BMW i3-REx:

I'm updating the flyer to include "carbon fiber body, aluminum frame."

Bob Wilson