Sudden Increase in Estimated EV Mileage

[CFBrand3rd]

So…2018 Touring PHEV, current mileage 34,436.

I live in Central Florida, it’s been in the upper 90s (F) for the last few weeks. My typical EV drive includes a high percentage of highway miles, very little stop & go, and I use the remote climate control a lot to cool down the car when I’m returning to the car after it’s been parked in the sun. With this kind of use, I typically see full charge estimates of 38-42 on the ol’ Guess-O-Meter.

I had my windshield replaced last week, and I finally got the car into the Honda dealer today to get the driver assistance systems recalibrated. When I dropped it off, it was showing 23.6 miles remaining; and 22.8 when I picked it up.

I drove home, plugged into Level 2, and came back a couple hours later to a 100% charge figure of 52.3 miles! I left to go pick up my granddaughter (which involved a 30 minute wait in the car with A/C blasting) then a quick trip to the grocery store and home; gone an hour, drove 11.2 miles G-O-M said 37.7 when I got home. Plugged it in again, checked on it an hour later, and now it’s full charged showing 52.6 miles of EV range!

Any clue what’s going on here? These are the highest figures I’ve ever seen. (My previous best was 50.3 after a serious hypermile drive shortly after I got the car.) Has this happened to anyone else? ‍


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[MrFixit]

Has this happened to anyone else? ‍

I will hazard a guess that you have experienced a 'battery capacity reset'. This can occur with an extended disconnect of the 12V battery. I think this can also occur when a dealer initiates some sort of reset within their iHDS diagnostic system. When this happens, the internal capacity measurement is reset to 55 Ah (just like a new vehicle). I suspect this also re-initializes the GOM.

I have a feeling that your EV range will return to 'normal' after you conduct several of your 'typical' drives.

If you use one of the methods described in this forum to read out your battery capacity, you may see that it is artificially inflated to ~55 Ah due to this reset, and it will slowly return to the correct reading for your vehicle. It takes surprisingly long for the battery capacity to return to 'normal' (could be months) depending on your driving scenario.

If you are not familiar with how to read your battery capacity, you can see details here:
https://github.com/clarity-phev/Battery-Capacity-Read

There is a brief discussion of this battery capacity reset at the bottom of the page.

 

[CFBrand3rd]

I will hazard a guess that you have experienced a 'battery capacity reset'. This can occur with an extended disconnect of the 12V battery. I think this can also occur when a dealer initiates some sort of reset within their iHDS diagnostic system. When this happens, the internal capacity measurement is reset to 55 Ah (just like a new vehicle). I suspect this also re-initializes the GOM.

I have a feeling that your EV range will return to 'normal' after you conduct several of your 'typical' drives.

If you use one of the methods described in this forum to read out your battery capacity, you may see that it is artificially inflated to ~55 Ah due to this reset, and it will slowly return to the correct reading for your vehicle. It takes surprisingly long for the battery capacity to return to 'normal' (could be months) depending on your driving scenario.

If you are not familiar with how to read your battery capacity, you can see details here:
https://github.com/clarity-phev/Battery-Capacity-Read

There is a brief discussion of this battery capacity reset at the bottom of the page.

I’d actually considered that, but I thought it was strange that none of my personalization settings went away. Kinda the opposite of when I had the 12 volt battery replaced.

I guess this means they didn’t secretly replace the traction battery with an updated unit!

Ahhh, well…I’ve been deliriously happy with the car over my 4.5 months of ownership, quirks and all. And I’ll be curious to see how this plays out…


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[MrFixit]

I’d actually considered that, but I thought it was strange that none of my personalization settings went away

Well, I am certain there is complex arrangement of parameters sprinkled throughout all of the many computers in any modern vehicle.

Some of these parameters are completely non-volatile (don't depend on power to be preserved). Some of them are volatile (disappear with any loss of power), and some of them may have a capacitor that lets them be held for a 'brief' time period. Personalizations are likely kept in a totally different module than the battery capacity values an it's not surprising that they would behave differently.

 

[Landshark]

Any clue what’s going on here?

This is becoming a popular inquiry.

The most likely explanation is that the 12V battery was disconnected at some point while the work was being performed. The EV range estimate has been reset.

Let us know if it doesn’t go back to the previous numbers after a week or so of driving under the previous conditions.

 

[CFBrand3rd]

This is becoming a popular inquiry.

The most likely explanation is that the 12V battery was disconnected at some point while the work was being performed. The EV range estimate has been reset.

Let us know if it doesn’t go back to the previous numbers after a week or so of driving under the previous conditions.

I honestly believe it will go back to “normal” eventually, but, hilariously, my overnight charging session showed 53.1 this morning and, after running about 35 miles of errands today, my afternoon charge produced 53.3! I swear I’m not making this up!

Weird…


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[insightman]

I honestly believe it will go back to “normal” eventually, but, hilariously, my overnight charging session showed 53.1 this morning and, after running about 35 miles of errands today, my afternoon charge produced 53.3! I swear I’m not making this up!

Weird…


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Can you test to see how far a 53.3-mile GOM read-out can take you? I apologize if this test requires you to burn a little gas to get back home after your traction battery's discharged. The ICE backup makes GOM testing a lot easier in a PHEV than in a BEV (I'm ignoring the ICE GOM.)

 

[CFBrand3rd]

Can you test to see how far a 53.3-mile GOM read-out can take you? I apologize if this test requires you to burn a little gas to get back home after your traction battery's discharged. The ICE backup makes GOM testing a lot easier in a PHEV than in a BEV (I'm ignoring the ICE GOM.)

I will do that.

Let me say that I have “Trip B” set to zero out every time I charge, and I plug in every time I come home, so it’s easy to keep track of how far I’ve driven.

And, I need to point out that, adding miles driven to miles remaining, the total decreases from the estimated range shows when unplugged. Example: My last outing yesterday of 35.2 miles left the GOM showing 12.3 miles remaining. This was after a typical day of running local 45 mph posted highways at about 5 over, and sitting in the 90°+ heat for 45 minutes (with the A/C set at 70) waiting for my granddaughter. A similar trip last week (in, admittedly, hotter weather) had me driving home on the ICE with EV exhausted at 38 miles.

I dunno. They obviously didn’t charge it when in for service, but I’m undeniably seeing a slight range boost. Could something they did have a positive effect on pack balance?


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[Landshark]

My typical EV drive includes a high percentage of highway miles, very little stop & go, and I use the remote climate control a lot to cool down the car when I’m returning to the car after it’s been parked in the sun. With this kind of use, I typically see full charge estimates of 38-42 on the ol’ Guess-O-Meter.

my overnight charging session showed 53.1 this morning and, after running about 35 miles of errands today, my afternoon charge produced 53.3!

This was after a typical day of running local 45 mph posted highways at about 5 over, and sitting in the 90°+ heat for 45 minutes (with the A/C set at 70) waiting for my granddaughter.

You’ve described two different driving conditions. One is a high percentage of freeway driving with very little stop and go, the other is running errands, stop and go, at lower speeds.

If possible, try repeating the conditions that produced the 38-42 mile EV range estimates for several consecutive days or more. It’s only been 2 days and so far you’ve been running local errands rather than what you described as your typical EV drive. The results thus far are exactly what would be expected.

Give it some time before we start speculating on mysterious procedures at the service department.

 

[CFBrand3rd]

You’ve described two different driving conditions. One is a high percentage of freeway driving with very little stop and go, the other is running errands, stop and go, at lower speeds.

With all due respect, my errands the other day involved a trip to Costco & the vet. (Primarily 3 different limited access highways; 2 6 lane toll roads and an 8 lane Interstate)

Yes; there are surface street options that would save 2 miles…and double travel times. Welcome to Central Florida.

Your errands may vary…


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[CFBrand3rd]

With all due respect, my errands the other day involved a trip to Costco & the vet. (Primarily 3 different limited access highways; 2 6 lane toll roads and an 8 lane Interstate)

Yes; there are surface street options that would save 2 miles…and double travel times. Welcome to Central Florida.

Your errands may vary…


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This morning:

Regardless of how I’m driving, this appears to be going the wrong way…


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[Landshark]

Your errands may vary…

My errands are irrelevant to the matter.

Best of luck.