Nashville BMW i3 benchmark

[bwilson4web]

In 2016, I ran a BMW i3-REx benchmark from Huntsville-to-Nashville in EV. I returned on gas:

• 2016 vs 2023
• EV: $24 vs $13
• Gas: $6 vs $8

NOTES:

The first benchmark was with a 2014 BMW i3-REx with 60 Ah (18 kWh) battery. The second was a 2017 BMW i3-REx with 90 Ah (28 kWh) battery. The 2014 had Bridgestone front and back inflated to maximum sidewall, 51 psi. The 2017 had Hancock on the front and Bridgestone on the rear inflated to maximum Hancock, 47 psi.

In 2016, the only available CCS-1, fast DC, an Electrify America station added 25 miles in Manchester TN. In 2023 test, there was an Electrify America station 2 miles added at Franklin TN. The Franklin Electrify America station required moving the car to a second charging lane because of a broken card reader. The second one was in degraded mode which to add 4 kWh 'for free' at a slow, 25 kW. At the destination, I charged at the same EVgo station from both benchmarks but the 2017 had a peak rate of 38 kW versus the 2014 48 kW.

Premium gas (recommended for BMW) was bought at the same Costco in both benchmarks. On the return, the high 91 F temperatures required operating the air conditioner. I also took a short biology break leaving the A/C on for the dogs.

IMPESSIONS:

• More Electrify America stations and CCS-1 stations makes EV travel possible.
• BMW, max 38 kW charge rate makes long distance EV travel impractical.
  • Coded to allow REx at 75% permits practical cross country on gas.
• The 2017 BMW is a practical, backup for our 2019 Tesla Model 3
  • At $15,000 more affordable and usable than other EVs
  • REx sidesteps the CCS-1 mess
  • Low 38 kW charge rate negates a Supercharger adapter

Bob Wilson

 

[alohart]

At the destination, I charged at the same EVgo station from both benchmarks but the 2017 had a peak rate of 38 kW versus the 2014 48 kW.

Low 38 kW charge rate negates a Supercharger adapter

The i3's maximum DC charging power hasn't changed over the years. It's always been a nominal 50 kW although in the real world, the maximum tends to be a few kW's less. Something abnormal must have been happening that limited the charging power of your 2017 REx to 38 kW. Some potential explanations would be that the DC fast charger wasn't functioning normally, the charger and/or your battery pack were too hot thus limiting the charging power, or your i3's DC charging circuit wasn't functioning normally.

 

[bwilson4web]

I sure hope it was heat. So far, no error indications even after running the center console controller check.

Here is the EVgo image of the charge curve:

I had added 4 kWh at a failing Electrify America station. But the station limited charging to 25 kW. The final EVgo screen showed 23 kWh at 92% which projects to 25 kWh.

Regardless, 50 kW is slow on a Tesla Supercharger. I typically get an initial 178 kW with a triangular slope down over the next hour. Based on the trip meter shown 4.3 mi/kWh, 50 kW would be 215 mi/hr charging rate.

Bob Wilson

 

[Arm]

In 2016, I ran a BMW i3-REx benchmark from Huntsville-to-Nashville in EV. I returned on gas:

• 2016 vs 2023
• EV: $24 vs $13
• Gas: $6 vs $8

NOTES:

The first benchmark was with a 2014 BMW i3-REx with 60 Ah (18 kWh) battery. The second was a 2017 BMW i3-REx with 90 Ah (28 kWh) battery. The 2014 had Bridgestone front and back inflated to maximum sidewall, 51 psi. The 2017 had Hancock on the front and Bridgestone on the rear inflated to maximum Hancock, 47 psi.

In 2016, the only available CCS-1, fast DC, an Electrify America station added 25 miles in Manchester TN. In 2023 test, there was an Electrify America station 2 miles added at Franklin TN. The Franklin Electrify America station required moving the car to a second charging lane because of a broken card reader. The second one was in degraded mode which to add 4 kWh 'for free' at a slow, 25 kW. At the destination, I charged at the same EVgo station from both benchmarks but the 2017 had a peak rate of 38 kW versus the 2014 48 kW.

Premium gas (recommended for BMW) was bought at the same Costco in both benchmarks. On the return, the high 91 F temperatures required operating the air conditioner. I also took a short biology break leaving the A/C on for the dogs.

IMPESSIONS:

• More Electrify America stations and CCS-1 stations makes EV travel possible.
• BMW, max 38 kW charge rate makes long distance EV travel impractical.
  • Coded to allow REx at 75% permits practical cross country on gas.
• The 2017 BMW is a practical, backup for our 2019 Tesla Model 3
  • At $15,000 more affordable and usable than other EVs
  • REx sidesteps the CCS-1 mess
  • Low 38 kW charge rate negates a Supercharger adapter

Bob Wilson

51 PSI??? That's too high IMO. No need to do that! BTW, I've seen that limited charging rate on a few of my i3's as well. Not sure if it's the chargers or the car. It's not heat...because when I saw those values it wasn't hot. But then again, I can count on one hand how many times I've fast charged out in the wild.

 

[mojo]

51 PSI??? That's too high IMO.

Agreed - it's way too high IMO too. Factory recommended pressures are 36 and 41PSI, so you'll be running with a dangerously small contact patch, I would think.

 

[alohart]

51 PSI??? That's too high IMO. No need to do that!

Since I bought our 2014 BEV new, I've inflated the rear tires to the sidewall maximum inflation pressure, 51 psi, with the front tires maintaining the recommended pressure differential of 8 psi, so 43 psi. That's 10 psi over the recommended inflation pressures.

The recommended inflation pressure differential of our 2019 BEV is only 5 psi, so I've inflated the front tires to 46 psi with the rear tires, 51 psi, 7 psi over the recommended inflation pressures.

I've carefully measured tire tread depths over 8 years recording tread depths on the inner, center, and outer treads on all 4 tires. The only uneven tread wear I've measured is on the right rear tire which wears faster than the left rear tire which seems to be a common observation for BMW's. I've compensated by rotating the tires side to side.

I've not seen the center tread wearing faster as might be expected when running increased inflation pressures although I think that's more likely with bias ply rather than radial ply tires. Because the contact patch decreases with increased inflation pressure, traction is probably slightly reduced. The ride is also slightly rougher. On the positive side, the risk of wheel or tire damage when running over one of our many potholes is reduced. The tires' rolling resistance is slightly reduced with the actual range slightly increased. At the recommended inflation pressures, our i3's have felt more sluggish than at the higher inflation pressures. They don't seem to roll as freely.

Running higher than recommended tire inflation pressures isn't for everyone, I suppose. However, I've been quite happy doing so.

 

[bwilson4web]

Thanks! I forgot about the tire pressure differential.

The rears are Bridgestone ECOPIA 175/60R19 86Q which are rated 51 psi per "TIRESIZE.COM". I'm having difficulty finding it on the side wall so I asked "Tire Rack":

• 11:10, Aug 1
  You: What is the maximum sidewall pressure for Bridgestone ECOPIA 175/60R19 86Q?
  Info: Welcome! We're excited to offer you messaging, allowing you to reply to us in your own time. An agent should reply within 1 minute
• 11:10, Aug 1
  Virtual Assistant: What is the year, make, model, and trim level of your vehicle?
• 11:11, Aug 1
  You: 2017 BMW i3 Range Exnder
• 11:11, Aug 1
  Virtual Assistant: A specialist will be with you shortly.
  Info: You are being transfered to another agent
• 11:11, Aug 1
  George: 51 PSI
• 11:12, Aug 1
  You: Thank you.

I was able to read the front tire sidewall pressure and used that for the front and rear. But now I feel confident to fully inflate the rears.

My primary goal is to see the tire temperatures front and rear equal or near equal. Also at the lowest temperatures practical for this hot summer.

Do we know the weight balance between the front and rear tires?

Bob Wilson

 

[alohart]

Do we know the weight balance between the front and rear tires?

45%F/55%R for a 2014 REx. Likely the same for a 2016 REx.