REx usage after 5.1k miles

Just did the sums today and we've used the REx for about 200 miles out of the 5,100 miles we've done in our i3. That's just under 4%, yet in line with what I predicted. Also, my work situation can change, as I work on medium term contracts. Therefore, I'm glad I've got the REx safety buffer.

Nice! Have you been able to figure out roughly the extra cost on your electricity bill? What price per kWh are you at?

psquare said:

Just did the sums today and we've used the REx for about 200 miles out of the 5,100 miles we've done in our i3. That's just under 4%, yet in line with what I predicted. Also, my work situation can change, as I work on medium term contracts. Therefore, I'm glad I've got the REx safety buffer.

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Curious how are you tracking the Rex vs non Rex mileage, are you tracking manually? It would be something interesting to do.

It's a guesstimate, based on my memory and REx refills.

It took me over 2 months to use up the 9 litres of delivery petrol, would you believe it.

I agree with you. it would be great if the car could give out REx stats like mileage and consumption. There's no reason for it not to have that.

spinball said:

Nice! Have you been able to figure out roughly the extra cost on your electricity bill? What price per kWh are you at?

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Hi, I had to think about your question for a moment, but I think you're after the additional electricity consumption due to the 120 additional kilos of the REx. Good question. I'd estimate it around the 10-15% mark, as that's roughly the additional weight when you compare it to the BEV.

As I said before, I would have loved to have bought a BEV, but the range extender was the more sensible choice for us as first-time EV owners. My potentially fluctuating mileage was also a key reason.

psquare said:

It's a guesstimate, based on my memory and REx refills.

It took me over 2 months to use up the 9 litres of delivery petrol, would you believe it.

I agree with you. it would be great if the car could give out REx stats like mileage and consumption. There's no reason for it not to have that.

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Actually that's a good idea, its easy enough to track the refills as they aren't that many. One thing I liked about the badly named "CarWings" is that it gave you online usage/efficiency/tracking data for the car. I haven't found anything like that in the BMW portal, I am assuming its not there (or I have yet to find it).

It wasn't critical, just fun to occasionally see the efficiency and usage over times or year, etc.

psquare said:

spinball said:

Nice! Have you been able to figure out roughly the extra cost on your electricity bill? What price per kWh are you at?

Click to expand...

Hi, I had to think about your question for a moment, but I think you're after the additional electricity consumption due to the 120 additional kilos of the REx. Good question. I'd estimate it around the 10-15% mark, as that's roughly the additional weight when you compare it to the BEV.

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No, nothing about REx vs BEV. I meant have you been able to figure out how much your kWh usage increased on your monthly energy bill? I was making the assumption that you are charging at home where you receive a monthly bill. Probably not safe to assume you are in the same situation as me--Sorry about that. Maybe you only charge via public chargers...

With a gas car it's easy to calculate fuel cost because you always pay per transaction at a gas station. With an EV and charging at home it's a lot more difficult as the energy usage is just lumped in with the rest of the house. I agree the car should track this itself as it would be trivial (yes I know not perfectly accurate with losses, etc, but should be close enough).

I meant have you been able to figure out how much your kWh usage increased on your monthly energy bill?

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Last month I did 1004 miles and used 173 kWhrs at home (I charged sometimes at motorway service stations (free) and used a little ReX but not much. I pay 12.5p per kWhr at home so this equates to 2.15p/mile, I think.

The car does track consumption and electrical miles. I have the android app and it will give you the all-time m/kWh (4.3 for me) and the electrical miles. There may be hiccups with software resets on the consumption though. And you need to factor in charger losses etc.

Edit: Your consumption seems remarkably low giving nearly 6m/kWh. Are you sure of the figures?

BrianStanier said:

The car does track consumption and electrical miles. I have the android app and it will give you the all-time m/kWh (4.3 for me) and the electrical miles. There may be hiccups with software resets on the consumption though. And you need to factor in charger losses etc.

Edit: Your consumption seems remarkably low giving nearly 6m/kWh. Are you sure of the figures?

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Do the electric miles exclude the REx miles? I seem to remember it does not, but could be wrong.

4.3 m/kWh is very good! Mine currently is 4.

psquare said:

BrianStanier said:

The car does track consumption and electrical miles. I have the android app and it will give you the all-time m/kWh (4.3 for me) and the electrical miles. There may be hiccups with software resets on the consumption though. And you need to factor in charger losses etc.

Edit: Your consumption seems remarkably low giving nearly 6m/kWh. Are you sure of the figures?

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Do the electric miles exclude the REx miles? I seem to remember it does not, but could be wrong.

4.3 m/kWh is very good! Mine currently is 4.

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Curious is are your tire inflation? I went from averaging 4.0 to around 4.5 by going up.

2.15p is about 3 cents USD. Thanks, that's inline with my calculations.

Hmm yeah I see it apparently does show this in the app. I'm at 4.3 mi/kWh over 528 miles. Not bad at all!

epirali said:

psquare said:

Curious is are your tire inflation? I went from averaging 4.0 to around 4.5 by going up.

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Interesting.

I'm a "bar" guy.

Vehicle Info says 2.2 front and 2.8 rear, which is in line with what the door label says.

Update: the front could actually do with another 0.3 bar, I've just discovered. I'll try that.

psquare said:

epirali said:

psquare said:

Curious is are your tire inflation? I went from averaging 4.0 to around 4.5 by going up.

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Interesting.

I'm a "bar" guy.

Vehicle Info says 2.2 front and 2.8 rear, which is in line with what the door label says.

Update: the front could actually do with another 0.3 bar, I've just discovered. I'll try that.

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Yeah we are still on PSI, and inches, and I think stones (oh wait).

Definitely try it, it does make a big difference.

Tracking the Electric Miles vs Rex is fairly straightforward with Android App and as has been pointed out you get a running average of miles per Kwh, I just keep updating the mpg figure in my Sig block every time I use the flap of shame

PluviaPlumbum said:

every time I use the flap of shame

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Ha, I'm going to steal this expression. :mrgreen:

Be my guest I stole it from the i3 facebook community which is also a very good source of useful info!

Many of us refer to it as the flap of freedom....