New to me 17' Rex questions

[greenlion]

Hello all, been a lurker now an owner and have a question regarding the rex that possibly has been rehashed a thousand times on here so dont flame me too hard, i work and live in San Diego M-F,my commute to and from the office is 8 miles total,I've ridden my MTB to work but during summer months im pouring sweat on arrival to the office and thats not ideal,I even rented an electric scooter but carrying my stuff is too cumbersome not to mention i almost got taken out on three different occasions by distracted drivers ,so enter my new to me I3, my main residence is in North OC, so im driving 170ish miles round trip 4 times a month, i just did the drive for the first time friday night on a full charge and full rex, to my surprise i started in on the rex 50 some miles into my 87 mile journey,granted, there is consistent hills involved on my drive and i was coasting for some recharge but nevertheless i even encountered the "low power possible"message at one point. Is this something to expect or is it my driving the car differently than it was intended?sorry in advance for my detailed story !thnx in advance

 

[TheMK]

The first thing you want to do is code your REx. This will allow you to manually turn it off and on as long as your SoC is less than 75%. You can also increase the size of the gas tank to 9L (2.38 gallons) for more REx driving range. By doing this instead of running the REx while your battery is at 6.5%, you can run it at a higher battery percentage and avoid the reduce power possible situation.


50 miles when starting from full charge seems a bit low, especially for a 2017 which has a 94Ah battery. Some questions to ask yourself. Was the heater running? How fast was I going? How steep were the hills? If the heater is blasting, you are going 70MPH on the freeway while climbing hills, I guess 50mi could be expected. The i3 is most efficient around town, and while it's fine at cruising speed on the freeway, it gets less range than if it were to be driven exclusively in the city. If you want to check your efficiency, you can press the "BC" button at the end of the turn signal stalk to cycle through information displays in the instrument cluster, one of them is efficiency, indicated by a little plug/cord icon and "mi/KWh".

 

[jadnashuanh]

I think it was the early '17 MY that had the larger battery optional, but maybe not.

The 34Hp engine just can't produce enough power to keep the car going uphill when it has a low battery...the electric motor can pull up to 170Hp, not counting what else is running the car, so 34Hp looks kind of anemic. It can keep up on the level unless you're flying too fast.

 

[greenlion]

thank you for your replies, looking forward to coding,just purchased the bimmer app and bought a vgate from amazon

 

[theothertom]

Fifty miles on a fully charged '17 is too low. Depending on temp, speed, wind, etc, should be at least 80-90. Look at the sticker on the driver's side door jamb to make sure of the date of manufacturer, or run the VIN on one of the web based VIN search tools. If it's really a '17, I recommend taking it to the dealer and have your battery checked. Either way, though, you should code your car.
Edit: Oh, and don't forget to check you tire pressure

 

[greenlion]

ya i was heavy on the accelerator averaging 75-85 mph,there is a few long grades for those of you familiar with the 15 freeway north from San Diego,heater on ,pretty cold out (for us cali folks) but still 50 miles range ?

 

[jadnashuanh]

The drag goes up with a cubed factor, so, yes throw in the speed and the grades, that range is possible. The car was designed for city operation, with a possibility to extend that with the REx if needed. It was not optimized for longer trips at high speeds.

Take an ICE at say 55mph versus 80mph, and its efficiency will drop considerably, too. An ICE doesn't need to burn extra fuel to warm the car, either...the REx does. FWIW, the BEV is more efficient with heating because it has a heat pump, but on the REx, every watt of heat you need, decreases your range one watt.

If you want to preserve range, slow down, and if available on yours, more seat heater versus cabin heating can help.

 

[bwilson4web]

For coding, I use:

• "ECO Pro" - midway between the default "COMFORT" and torturous "ECO Pro+", it moderates the acceleration to get more range. You still have HVAC so the cabin remains comfortable.
• key fob "Panic" becomes "pre-condition" - hitting the button about 20 minutes before leaving while the car is on a charger, will heat or cool the cabin as needed before you walk to the car. It will be comfortable and you can use a less aggressive temperature setting. You can do the same with the smart phone app but this works when within key fob range. FYI, when on a charger, my car heating only blows 'cold air' but enabling "pre-conditioning" makes it blow warm air again.
• "enable 75%" - you'll soon learn to turn on the REx early as this will preserve the EV charge and most of all, give battery storage buffer to handle hills and high speed bursts.
• use dynamic cruise control - this will smoothly handle speed changes, better than a human, to minimize energy loss and ease the driving load. You'll arrive less tired.

There are other tricks like: (1) having a 4-wheel alignment (ask to minimize camber); (2) run tires at maximum sidewall pressure (ride gets harder but rolling resistance goes down and handling improves,) and; (3) front cover to handle times when there is no ready shade. I replaced my vehicle, portable charger with a multi-voltage, 120-240VAC, multi-current, 12-32A, charger. With plug adapters, I can use ordinary house outlets, NEMA 5-15 to NEMA 14-50 (i.e., full power, L2 charging.)

Bob Wilson

 

[greenlion]

thanx for all the responses and thank you Bob for your coding insight, i received my vgate last night and am looking forward to using your recommendations , I am in love with this car and knew it was user error getting such low range but thanks to all your useful insight i will begin to enjoy it so much more, thnx again,

 

[Srivenkat]

Hello all, been a lurker now an owner and have a question regarding the rex that possibly has been rehashed a thousand times on here so dont flame me too hard, i work and live in San Diego M-F,my commute to and from the office is 8 miles total,I've ridden my MTB to work but during summer months im pouring sweat on arrival to the office and thats not ideal,I even rented an electric scooter but carrying my stuff is too cumbersome not to mention i almost got taken out on three different occasions by distracted drivers ,so enter my new to me I3, my main residence is in North OC, so im driving 170ish miles round trip 4 times a month, i just did the drive for the first time friday night on a full charge and full rex, to my surprise i started in on the rex 50 some miles into my 87 mile journey,granted, there is consistent hills involved on my drive and i was coasting for some recharge but nevertheless i even encountered the "low power possible"message at one point. Is this something to expect or is it my driving the car differently than it was intended?sorry in advance for my detailed story !thnx in advance

I see you are a bit "long-winded" with your BEV, but with extended ReX "periods" you would be alright. :lol:

 

[jadnashuanh]

The REx was designed as an emergency 'get me home' tool, not an extended long trip enabler. So, because of that, it does have some limitations. Yes, people do use theirs for longer trips. Some of those limitations are as follows:
1. The fuel tank is only a bit over 2g, and offers approximately 34-40mpg...IOW, not much
2. If you do ever let the SOC drop below about 4%, the car will start to limit some functions like HVAC, max acceleration, and ultimately, max speed
3. Even if you have reprogrammed the car for a higher range hold value, each time you shut it off, whatever the SOC is then becomes your new maximum. The only way to boost that is to recharge the battery.
4. Like any vehicle, speed and long grades will affect your ultimate range.
5. The REx relies entirely on resistance heating for the cabin warming. This is far less efficient than the BEV's heat pump unless it is really frigid, when the BEV then reverts to its backup resistance heating. Under most circumstances, the BEV won't enable the resistance heating.

If you understand and accept those limitations, yes, you can successfully take your car on a long trip. It's not your typical hybrid. Just plan to stop for fuel about once an hour or so. That does cut into your average trip mph values. On my ICE, the car can go nearly 500-miles before it has to stop, whereas, I generally need to more often. Driving where gas stations may not be open or spaced appropriately can become a challenge on completing your trip, depending on your desired route. You may have to make some compromises.

 

[REvans2001]

I heartily agree with Srivenkat

 

[sipabit]

Just wanted to make sure you understand how the REX works b/c it may not be that intuitive and it's not like BMW really explains it. The REX is essentially a generator that produces electricity for the battery so when you're running on gas, you're still using electricity. There's no actual gas motor that powers the wheels.

So what this means is that there's a specific rate that the REX is giving your car electricity. If the rate at which you use the electricity surpasses the rate at which the REX is generating it, you'll eventually hit a point where the car can only go as quickly as the car is getting electricity (as opposed to using excess). The REX isn't that strong, so your car will slow to ridiculously slow speeds (the same as what the REX does for the scooter that it came from, except it's carrying a bunch more weight).

So that's why others here are recommending that you have the REX start early so that you have plenty of electricity to use while the REX is operating. When there's high demand on the car, the REX is essentially creating extra electricity for you but not enough to really propel the car in the way that its demanding. It just gives you more time for the electricity to run out.

Sorry if this is redundant and you already knew all this. It wasn't obvious to me when i first learned about it, so figured I'd share.