Rex Junior and the tale of comfy winter driving without using the heater.

BMW i3 Forum

Help Support BMW i3 Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

JohnKelly

Well-known member
Joined
Oct 7, 2017
Messages
128
I have just returned from a 1,650 mile round trip from the Washington state coast to Bozeman, Montana and back in my 2015 Rex. I took off on Monday at 5am and returned Friday afternoon. Spent Wednesday at a book reading by my beloved 85 year old aunt in Bozeman. Used DC fast chargers 11 times for a total of about $100, stopped for gas 13 times for a total of 27.2 gallons and a cost of about $88 for the trip, plugged in overnight on a free level 2 where I was staying for the night on two occasions, and plugged in at free level two in order to top off the battery while in Bozeman. The whole trip went flawlessly.

Temperatures in the single digits overnight and mostly in the teens and twenties during the day. Multiple major elevation changes throughout the trip including mountain passes. Went from sea level to well over 6,000’. I travelled 515 miles the first day. It was snowing in Bozeman with everything but the arterials covered with hard packed snow with lumps and ruts everywhere. It was snowing hard at Snoqualmie pass in the Cascade mountains on my return trip, but most of the roads on my trip were bare.

I had previously installed Nokian R3 155/70/19 winter tires on my 5-1/2” wide rear wheels and 5” wide front wheels… yes they fit despite what you may have heard, and they performed beautifully. I made some chains from two sets of chains designed for 155-70-13 wheels. Shortened one set and attached them to full length set to make chains that fit. I was kind of looking forward to having a chance to use them, but the chains required warning was lifted for Snoqualmie pass a few hours before I got there.

I used almost no heat and could have easily done the whole trip with no heat! I did not use the seat heat. Now, before you guffaw and relentlessly ridicule me for being a liar, please let me explain : ) I have a Rex Junior! In my case, the coldest parts of my body while driving are my ankles… most peculiar, I know. I purchased a solar generator from an Idaho company called Inergy. The Apex model. It is pricey, but you can charge it by plugging in, or with solar panels. It also works well for powering electric lap blankets and a TV during power outages if we do not want to start our noisy generator at home. It has an inverter built in. It is small and portable and weighs only 25 lbs!

I bought two Sunbeam heat therapy wraps… one for each ankle. Wore long johns and two pairs of Merino wool socks and wrapped the heat wraps over them with the plugs hanging out of my boots. I also wore pants, because very few things are more grotesque than an old man wandering around in long johns asking where the bathroom and coffee machine are : ) Strapped the solar Rex Jr. in behind the seats where I could see the read-out. Very nice to stay warm while sitting waiting for your charge to get to 80-85%. I think I could probably drive as many as 24 hours this way without charging the Apex. I took along an electric lap blanket just in case, but I never used it. It uses much more wattage than the ankle wraps. From past experiments, I believe I could have used the blanket for ten hours of so before depleting the battery of Rex Junior. I charged the Rex Junior overnight at the places I stayed although it never got below 80%.

I used the vehicle heat for about 10 minutes on the way to my destination and about 1/2 hour on the way back, but it was completely unnecessary. This allowed me my maximum electric range potential by saving the battery for driving with defrost on the lowest setting of 60 degrees. I drove in Eco Pro mode most of the trip. I drove the speed limit or slightly under where traffic allowed… and the traffic was great for most of the trip. So 65-75 MPH on the highway for the most part. The only slightly unpleasant time was with some strong sidewinds that had me wandering in my lane for a bit, so I slowed down, which helped.

I hope this explains to the skeptical how the i3 Rex can be used for longer trips without the need for a back up gas guzzler and all the attendant hassles of more insurance payments and all the upkeep involved in owning a second car. The i3 Rex is a brilliant piece of engineering that allows driving full electric most of the time, and until the EV infrastructure becomes more ubiquitous and reliable, it is the best of both worlds wrapped up in a seamless package.

I also hope this will be of some help to Bev owners with small batteries. Cheaper than having to buy a car with more range as your battery slowly degrades overtime! I use the Rex Junior for our weekly shopping trips (we live in a tiny town) and no longer have to deploy the Rex for winter heat during these 60-70 mile round trips. My wife gets by fine with the electric throw blanket and seat heat.

There is another similar, but less attractive (to me) Rex Junior option called a cab heater that truckers use.. a small diesel powered heater. Here is a great write up on an EV install of that:

http://kiwiev.com/installing-a-diesel-parking-heater/

And here is a link to Inergy:

https://inergytek.com
 
Thanks for sharing the interesting travelog!

Curious to learn if you have ever tried to slow charge Rex Senior using Rex Junior (will the i3 charge using using only the solar generator and occasional use J1722 or turbocord cables)?
 
Thanks for the kind words! Not sure if it would keep up, but I think if you set the 110 volt charging to low it might... although it would not make much of a boost in the battery percentage : ) Might get you to a real charging station if you were very close though. Never thought of that.
 
... I'd just take an ICE car for that trip. Run the heat, go 100mph on the highways, not sweat the details.
 
Interesting read. Thanks for sharing.

I'm surprised that you were able to keep the windows clear in those temps running defrost on 60, but I'm also guessing that that worked to keep the car at about 60 so made it easier to get by without freezing.
 
"... I'd just take an ICE car for that trip. Run the heat, go 100mph on the highways, not sweat the details."

Well, bully for you! I use as little gas as possible everywhere I go, and that includes long trips. I have just one vehicle and am not about to rent a gas guzzling stink pot... and spend much more on gas, insurance, and rental fees. But you do you. I had a great time planning and executing this trip. And it went flawlessly. I am sharing this for others of a like mind. That does not appear to be you. I was actually more comfortable with ankle heat than I would have been with heating the whole interior, because the rest of my body gets way to hot if I have the heat up high enough for my ankles. In other words, my experience was superior to what it would have been in a gas guzzler in every way.
 
Actually having the defrost at 60 does not keep the interior anywhere near 60 when using Eco Pro mode with outside temperatures in the teens or twenties. It's better than nothing, but it's not real noticeable heat. If I could have gone without defrost, I would have. Thanks.
 
JohnKelly said:
I have just returned from a 1,650 mile round trip from the Washington state coast to Bozeman, Montana and back in my 2015 Rex. I took off on Monday at 5am and returned Friday afternoon. Spent Wednesday at a book reading . . . Used DC fast chargers 11 times for a total of about $100, stopped for gas 13 times for a total of 27.2 gallons and a cost of about $88 for the trip, plugged in overnight on a free level 2 where I was staying for the night on two occasions, and plugged in at free level two in order to top off the battery while in Bozeman. The whole trip went flawlessly.
. . .
First off, I fully appreciate your report. I'd done several benchmarks between Huntsville and Nashville, ~120 miles, in our BMW i3-REx only to find: ~$24 EV charges and ~$6 gas. Our longest trip was 700 mi each way, Huntsville AL to Stillwater OK, gas all the way. In Stillwater, the hotel gave us access to 120 VAC outlet. Based on ~39 MPG, we probably bought ~36 gallons, ~$108 for the ~1,400 miles. Back in 2016, there were no CCS-1 fast DC chargers along the route. But based on the charging costs, it would not have made sense.

The BMW i3-REx was our gateway to a Std. Rng. Plus Model 3 and away from a 2017 Prius Prime. In the January 2020 winter storms with 40 F headwinds and rain, we drove 1,980 mies, Huntsville AL - Allen TX - Coffeyville KS in our Tesla. Total Supercharger fees were $60. We also used free L2 chargers and stayed at motels with overnight charging.

Had we kept the 56 MPG Prius Prime, the 1,980 miles would have been $36 gallons, ~$90.

Bob Wilson
 
Thanks, Bob. I was fortunate to have the DC fast chargers available and working without any issues. This allowed me to decide how much gas I was going to consume instead of having it locked in. The short breaks for charging were acceptable to me now that I am older and not in much of a hurry : ) This same trip would have been much different without the fast chargers.
 
JohnKelly said:
There is another similar, but less attractive (to me) Rex Junior option called a cab heater that truckers use.. a small diesel powered heater. Here is a great write up on an EV install of that:

http://kiwiev.com/installing-a-diesel-parking-heater/
Our first EV was a 2012 U.S. Mitsubishi i-MiEV, similar to that described in the link. To increase winter range and provide better cabin heating, i-MiEV owners in cold climates began installing diesel or alcohol-powered auxiliary heaters that were plumbed into the stock heater which used an electric resistance element to heat a water-based heat transfer fluid, very similar to that in all i3's. If I had a REx and lived in a cold climate, I would consider installing an auxiliary heater that heats the standard heat transfer fluid rather than heating air as the described heater does. The i-MiEV installations were under the front hood near the heater pipes so the warm exhaust would not have to be routed out of the interior.
 
After trying many different approaches for trying to stay warm while commuting during really cold days without using the climate control, the best approach I have found (at least for me) is using the seat heater and a small Honeywell 250 watt ceramic heater plugged into a portable rechargeable AC/DC battery pack commonly used for camping. The battery pack, which weighs about 4 lbs, has enough charge to power the portable heater for the duration of my commute (about an hour), and the little heater warms the cabin quite nicely. If I need the heater on my evening commute, I recharge the battery pack at my office.
 
JohnKelly –

You've gone far above what most would do to extend range. A tip of the hat to you for the extremes you went to save kWhs!

From your posts here I'm inferring that you're ok with forgoing normal creature comforts.

For your next journey, may I suggest a browse of 12V heated clothing designed for motorcycle riders? This is not my area of expertise, but wanted to share the concept in case this is not on your radar...

(one source among many):
https://www.thewarmingstore.com/12v-motorcycle-heated-clothing.html

Stay warm!
 
Hey, thanks for the comment, but I was perfectly comfortable. That's the point. I did not sacrifice my comfort, I just extended my range. I would look into the heated motorcycle clothing if it were a better option for me, but it isn't since only my ankles get cold. Might be a good idea for those who don't have heated seats though. But, as I mentioned, I did not even need to use the seat heat, I was so comfortable.
 
Back
Top