Predicted Range

[advance2020]

Ok, so I don't often charge my car to 100% but this week was different. I have found the Predicted Range shown by my car varies a lot, to the point it is not helpful. So I thought I would share some stats.

On Friday I went on my Longest Day trip yet, to Weymouth, via Dorchester, around Dorset, and back via Blandford Forum. In total 117.7 miles, averaging 4.1miles/kWh (I was using Sport mode coming home, and it's uphill!)
As I set off with a full battery, Predicted Range (PR) was only 109 miles, which seemed a little worrying. Maybe because the battery was cold, as after a while having driven 10 miles or more the PR was still showing around 109 so Range had effectively increased to 120.

When I arrived at Dorchester, the 38 mile trip had only used up 30% battery - 70% still available. PR was 89 miles (89+38=127) But later, when I arrived at Portland PR was still 89 miles with the battery at 67% - I had Plugged at Tesco in Dorchester (a shame not to) - for a very short pitstop, adding 6% to battery. By now I was 54 miles from home.

By midday, after a Rapid Charge to 98% the PR was now showing a healthy 126 miles at 95% battery. Ambient temp was now 12°C and the battery was now nice and warm. Then by 14:15pm the PR was 100 miles with only 80% battery.

A similar experience today, setting off with 100% only to find PR was 109 miles again. However after a 20 mile trip to Shepton Mallet 4.5m/kWh and another Top Up @tesco the Predicted Range was 123 miles with 100% battery 4.5m/kWh. The ambient temp was warmer today, but PR was slightly less. Maybe the Rapid Charger in Portland warmed the battery more.

My conclusion is this has much to do with temperature of the battery, but I also feel that the car prefers to operate with 80% battery, and that charging to 100% is not the best way to maximise the cars range, or efficiency. And its also nice to stop charge short of 100% to allow for regen/One Pedal mode.

[londiniumperson]

I've found that the predicted range is based on the efficiency on the last mile or so of the most recent journey, not the whole of the last trip.
I know that's it's a pain, but please could you extract the journey duration, max speed & average speed of your separate trips from the app to give us number crunchers more to get our teeth into?

I've been following the MG ZS EV forum/Facebook group a while back and they are firmly of the belief that you have to make sure that you force a balance charge by leaving the car connected to the granny/home charger overnight and charge to 100% to ensure that the predicted range is as accurate and to give the best range as possible, maybe the Honda is similar.

[Left4Cookies]

I've found that the predicted range is based on the efficiency on the last mile or so of the most recent journey, not the whole of the last trip.

Do we know this for certain? I’m not disputing your claim, but it would be easy to test by rolling around very slowly for a mile and see total estimated range jump up after restarting the car?

[londiniumperson]

I've found that the predicted range is based on the efficiency on the last mile or so of the most recent journey, not the whole of the last trip.

Do we know this for certain? I’m not disputing your claim, but it would be easy to test by rolling around very slowly for a mile and see total estimated range jump up after restarting the car?

I'm not 100% sure, but my drive ends with the last few miles of 30-40 limits after about 20 miles of motorway/dual carriageway. The range usually increases between the end of that journey to work and the drive home even if the temperature is similar. There could well be other factors involved in my assumption like battery temperature, but I'm fairly sure that how the last few miles are driven, rather than the whole journey does have an impact on the indicated range for the next time the car's powered on. It's also very probable that I'm completely wrong because we have no data from the car/battery and battery temperature could be a factor.

[advance2020]

I wondered initially whether your Last Journey stats were a factor, but it is unlikely. My previous Journey was very short 2.4 miles and AVG was 3.5m/kWh. But the following day the PR was similar, when I set out cold, even though previous day I had averaged 4.1. My car should be able to access data on Average Consumption over longer periods. Although I reset my Trip B for Every Journey, I only reset Trip A every 1000 miles.

I think Honda may either just be “very conservative” with their Predictions from cold, until the car can monitor how one is driving, and/or the range increases once the chemicals in your battery wake up. I do agree that if your car is plugged in, just before you set off, PR will be better, as the battery will be warm.

[Number5]

Does the predicated range matter?
The car cannot know if you are going to drive like miss Daisy or like you stole it. Your route could be up a mountain.
Over a full charge 0% will appear @approx 100 miles if averaging 3.5 m/kW and 130 @4.8 m/kW.
All you need to know.

[advance2020]

This article from the USA may be of interest, although temperatures are more extreme than UK.
'Temperature can have up to a 40% effect on range':
Ford Mustang Mach-E's estimated range was driving owner nuts.
https://eu.usatoday.com/story/money/car ... 015932001/