Why the BMW i3-REx

I thought about that but a seasonal temperature, 76-78F in the summer, and say 64-68F winter is not that big of a burden. The heated seats might allow a lower range in the winter.

I understand that the parallel parking may be buggy and requires monitoring of what is going on. This evening it worked perfectly and as I got out, I saw the sign "ZIP CAR PARKING'. Huh??? ZIP CAR in Huntsville???

Bob Wilson

 

I've completed my highway model:

• 65 mph (indicate mph) is 24x7, sustainable speed
• Block-to-block speed with 15 min refueling is 50-53 mph (last quarter of tank)
  
• Block-to-block, 40 MPG

Any faster and the traction battery is slowly drained until the REx can no longer maintain speed. The battery drain, ~20%, means ONLY three cycles if starting at 75% and the REx enabled. At 75 mph, the block-to-block speed only goes up 5 mph over 65 mph indicated. Worse the fuel economy falls to 32 MPG from 40 MPG.

Prius measured data:

• 52 MPG@65 mph - Gen-1
• 52 MPG@70 mph - Gen-3

Questions?

Bob Wilson

 

I've been giving "demo drives" at work and learning more about how others drive and use their cars. Wednesday it was a guy who lives about 70 miles away. Without a charger at work, the BMW i3-REx would not work without coding and using the REx daily. He liked the acceleration and power but when I explained why 65 mph is the highest block-to-block speed, you could tell it was a deal breaker.

Now I'm OK with this because people need a car that meets their requirements. He'd heard from his wife that 'hybrids have no power.' I did not mention the next generation PiP but because it has the ability to use both MG1 and MG2, it may meet the acceleration requirement.

As for the BMW i3-REx and highway performance, the answer is an after-body to reduce aerodynamic drag. It could also carry 2-gallon spare gas cans to shorten the refueling time and widen the range of where to refuel.

Bob Wilson

 

The best the range extender will do is maintain the SOC found when you enable it. If regen brings the SOC higher, the range extender shuts down.

In an ideal world, you could identify what SOC % to maintain but it isn't coded that way. You have to wait until it is 75% or less and upon enabling, the range extender tries to keep it there.

Bob Wilson

 

I don't have the chart handy but it looks a lot like an Adkinsonized version of the motorcycle engine. The training materials indicate the engine does 'warm-up' before producing power which makes a lot of sense. The only significant thing missing is cooled-EGR.

Bob Wilson

 

Not that I can tell but I am just getting my OBD instrumentation setup. I can already tell some 'claims' about how the car works may be not be so accurate. But Argonne Labs has publicly available data.

Here is one early chart from an Argonne test:

The layers suggest:

1. 10 kW level
2. 7.5 kW level
3. 0 kW level
   
4. -1.5 kW level - starting the REx and warm-up??

There is a wealth of data at Argonne that I've not dived into, yet. My focus is more on getting OBD data and metrics from my car so I can investigate obscure areas they may not have benchmarked. For example, last weekend I ran a 75 mph benchmark. Also, I'm interesting the BSFC vs generator output. I want to know what is going on when at 75 mph the car gets 32 MPG. Also, how the REx output varies as the difference between the set SOC and actual increases.

Bob Wilson

ps. Attached a training file about the engine.

 

Cost: $4,770.00

Replace 1968, 100A service with 200A service and added NEMA 14-50 for charging the BMW i3-REx:


The original service cable had aged so much that the insulation was in patches and the "common" was exposed, loosely to the elements. The two hot wires were visible. This photo shows where the utility meter goes.


The technician is holding the control wires from the natural gas powered, emergency generator. The utility service enters from the top and feeds the circuit breaker panel on the lower right. The left cables are the power lines from the generator. The emergency generator comes on automatically 12 seconds after loss of power and isolates the generator power from the utility line. When the utility service returns, the service switches over and the gas engine shutsdown.


The gas line to the generator means no toting gasoline to the engine and filling a small tank. We're talking days, weeks of operation as long as the utility company provides natural gas.


Now this is the 19th century generator. Huge compared to MG1 coupled to an air-cooled engine. I would prefer a liquid cooled engine so waste heat could be salvaged. But good enough for now. At 16kW, it has enough power to charge the BMW i3-REx.


This is the former distribution box with the fuse holders. It was in service ~48 years.


Instead of the original 100A service, we upgraded to 200A ... big thick cables.

Now a skeptic would say, $4770 / $2 ~= 2,385 gallons. But the service line was weather aged and unsafe. With the hot weather, air conditioners have been working overtime and huh ... house fires. BTW, the NEMA 14-50 is 50A wire and 50A circuit breaker, 12 kW. Our BMW i3-REx has 7.4 kW, built-in charging capability, ~32A, so it should be pretty efficient.

Bob Wilson

 

I bought the JuiceBox with WiFi rated at 40A for the same reason ... RV park.

The BMW connect is OK but not enough engineering data. The JuiceBox appears to have the metrics I want.

Bob Wilson

 

They seem to like my bon mots. <GRINS>

Of course I'm biased but I kinda like: (1) strong motor, and (2) averaging range extender. I need to do more research but this is not a common architecture. Perhaps the Fisker?

What I'm finding is high-speeds greater than 65 mph, long distance, the BMW i3-REx is not the answer. But if you can do your cross country at 65 mph, the BMW i3-REx fully meets at least my requirements with 40 MPG. Our 2003 Prius gave 52 MPG at the same, 65 mph.

Bob Wilson