Newbie, confused by BMW salesman

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slipnslider

Member
Joined
Mar 18, 2017
Messages
12
Just test drove my first i3 and it was a used 2014 REX. I loved it.

But I was under the impression that once the battery is down to 6.5% and the REX comes on, I could keep driving with the REX as long as I'm willing to stop for gas every 70 miles or so.

He said this isn't the case, that after you run low on gas, you need to charge the battery.

But I've heard of people doing 500 mile roadtrips using the REX.

Is he right, or does he not even understand the car he's trying to sell me?
 
When the i3 first went on sale salespeople in Canada (Toronto) used to say that you could only fill the gas tank up to 3 times consecutively before recharging. If you didn't recharge as directed the warranty would be voided. They stopped saying that over a year ago.

Now whenever the battery is discharged to 6% we get an email recommending that the car be recharged to prevent damage to the battery.
 
In one year of ownership we have driven 6,500 km on REx out of 17,600 total km. Most of the gas mileage was on two long trips into northern US where there is little charging infrastructure.

We have found the REx to be essential for the way we want to use this vehicle.
 
If you get the car into the point where it will turn on the REx in the way it is configured in NA, you must understand that while the REx engine can produce enough energy to keep you moving at reasonable speeds, it is essentially just a 34Hp engine. When was the last time you drove a car with 34Hp? Plus, whatever the SOC is when you shut off the car, that's the maximum it will try to attain with the REx, so if you just were pushing it, and the charge got lower, that's the new max. If you're not careful, you'll essentially be stuck with a 34Hp car since there won't be anything left in the battery to act as a buffer. If you understand this, yes, you can drive the car as long as you keep filling the fuel tank, but you'll have max performance if you charge the battery up again. As sold elsewhere, you can turn the REx on with a 75% SOC, and thus preserve full capacity unless you want to drive with a full load, lights, heat, uphill at high speeds, then you'll be drawing down the battery. If you don't get it too low, it will recover some going down the next hill, but could get low enough to cause the car to slow down. Max continuous, flat road speed and being able to maintain charge seems to be about 70mph...faster, and you'll be depleting the batteries.

While some people use the i3 with REx for long trips (and it will work if you understand its limitations), the car was designed for short distances with the REx as an emergency backup, otherwise, they would have put in a larger engine so it could maintain performance forever. Many people buy the REx version and never use it except to test it. If you need it, fine, but it does add to the cost, complexity, and maintenance costs since you now have a muffler, oil, filter, spark plugs, etc., associated with the ICE. The REx is also less less efficient than the BEV, partly because of the extra weight, but also because it doesn't have the heat pump the BEV can, which means any heating is a 1:1 ratio from the battery:heat, whereas on the BEV, most heat is about a 3:1 heat: power use.
 
I bought the car in Charlotte NC and drove it 463 miles home that evening. I had already bought the 'code' USB stick and just a couple of blocks away, applied the patch. When I reached the Charlotte beltway, I enable the engine and it worked perfectly.

The ride home, I refueled at:
  • Henderson NC
  • Biltmore Park NC
  • Knoxville TN
  • Cleveland TN
  • Pittsburg TN
  • Huntsville AL

My wife and I drove 700 miles to and from Stillwater OK and stopped roughly every 70 miles each way. Outbound, I had a single "one gallon" refueling when a truck stop after midnight was closed.

Coded, the car can easily do cross-country trips following interstates and using the truck stops. Carry a 1 gallon spare gas can incase the stop is closed for the night. But I have no problem with doing 1,000 miles in a 24 hour period. Just be sure to get the dynamic cruise control option.

Bob Wilson
 
Greetings all, first post for me, I'm looking forward to being a (near) future i3 owner. I'd like to share my experience of my first test drive of the REX this past week. I contacted a sales person the night before and made an appointment to see a REX they had on the lot. When I pulled up the next morning, I could see him digging around under the hood of the car I picked out. Apparently, the battery had died and the car wouldn't start. He was attempting to jump start the car. Who knew, there is a small "traditional" car battery under the hood, mounted below the dash. So after some tinkering, he gets the car to power on, and immediately the REX motor kicks on. It sounds like a large lawn mower. Another salesman walks by and says "is it supposed to sound like that?" So we jump in and start the test drive. He drives towards the end of the lot and says we'll trade places once we get outside the gate. I look at the gauge and notice the battery is completely drained. He drives it, ever so slowly, as if to give it a few minutes to charge the battery. When we get outside the gate, he hops out and turns the car off. I jump in the drivers seat and the car won't start. Not a good look. Well, thankfully he had another REX on the lot that was charged and I got to test drive that one. Obviously, I didn't pick up the car. But at least I got to experience the REX motor and also confirm the car will not run with 0% battery, duh. And I figure the REX won't be enough to charge the battery if it's completely depleted.
 
Indeed. The car will not power up when the 12 volt auxiliary battery is flat as you have seen, even when here is enough charge in the high voltahe battery. All the car electronics run from this small battery. When the car is powered up, the high voltage battery will start charging the 12 volt battery if it needs it. When the high voltage battery is empty the rex will start immediately after activating the car and it will keep running untill there is 3 or 4 % charge if you stand still then it cuts out.
Realise that the rex needs to warm up before it will deliver full power. This takes about 5 minutes. I have never been in this situation but i would expect it to take 10 minutes to have a 3% charge on a complete flat from cold.
When i am driving with the rex activated in normal circumstances i can keep battery state of charge at 70mph, the tipping point is somewhere between 70 and 75 mph. Up hill, blowing a gale against or faster the battery will still go down.
 
As I understand it, BMW designed the REx as an emergency backup to keep you going. Yes, people do take their cars on long trips and just keep refilling the gas tank, but 70-miles might be pushing it, depending on where and how you're driving it. One of their hybrids with a significantly larger engine can just keep going. The i3 is not that car. In the USA, on some areas of interstates, the stations may be further apart than one tank can get you, or because of their spacing, you need to stop at each one along the way. Doable, yes, convenient, not particularly. Used as designed, I think it's a great car. Look at it like having the right tool for the job...a pair of pliers might work, but the proper sized wrench works better.
 
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