State of Charge: puzzle

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advance2020
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Post by advance2020 »

Let's hope this is one off. Have you ever had this experience.

Occasionally when I have charged overnight to say 80% or 85% when I get to my car the SoC might be showing 82 or 87% This hasn't happened often, usually during a warm spell, which is no doubt the reason. But today it was a Strange One.

I charged overnight to 80% - and the display showed 80% when I got to my car. Getting it out of my garage, shutting doors, gates etc, I often leave with 79% displayed. I then drove 7 miles to my local ASDA and plugged to an old Polar post, using my BP Pulse App. Once connected the car's display was showing 80% and this was within a minute, or two of the charge starting. How can this be? Ok, my 7 mile drive is slightly downhill, and it was a very efficient run, could have been 7m/kWh but this still means that I must have used a kWh getting there.

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How did this old 7kW Polar charger suddenly input a kWh Very strange.
This was taken at 09:49am Charge started at 09:47:06 according to the BP App
The App has added an Hour in error: see my BP Pulse post today

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Also, and this might seem a minor error, the main driver Display was White, rather than Green, even though the car was still being charged. The cable was showing Green on EV display

EE784CF6-5FDC-4C22-B411-64D62A1248CC.jpeg

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Platinum White Pearl: e-driving green at last, on R17 Michelin Pilot Sport
A fan of One Pedal Driving max >>> and physical buttons

darrenj1
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Post by darrenj1 »

I dont really get the question.

You are arguing about 1%?
Wee Peem
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Post by Wee Peem »

I think the accuracy of any of these state of charge readings may only be accurate to within 5% either way so 1% may actually mean nothing.
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londiniumperson
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Post by londiniumperson »

darrenj1 wrote: Fri Aug 20, 2021 12:20 pm I dont really get the question.

You are arguing about 1%?
It's quite simple, after driving 7 miles the SoC was 1% more than at beginning of the journey.
I'd love to be able to drive somewhere and end up with more charge than I started with, especially if it was anywhere near 7 miles :D
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
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londiniumperson
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Post by londiniumperson »

@advance2020, are you sure that you have a Honda e and didn't actually buy a self charging Toyota instead, with no need to plug-in? :lol:

This is supposition, but I have a theory.
If we assume that the initial indicated of 80% SoC was almost at 81% & you had a very efficient drive combined with what seems like quite a warm day being at 15°C at quarter to 10 in the morning, then maybe your battery was at the optimum temperature for efficiency.
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
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advance2020
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Post by advance2020 »

I guess, because I have seen so many "self-charging ads" on TV and online media, my car got jealous, and decided it would "Self Charge" to please me.
No, I don't understand it. I have kept a detailed record of ALL my daily journeys to date - sad but true - always taking photos of my dash for the record, and so far, with this one exception, they have always made sense. Which is partly why I posted this. I can only assume it is a software glitch, and therefore wanted to know if anyone else had ever had the same experience. However one would have to be as anal as me, to keep such a close eye on this stuff.

It is possible that although the display was was showing me 80/79% at the start of my journey, having charged overnight to a 80% limit, the battery might have been in an optimum state and effectively at say 82% SoC, and when I arrived the SoC could have been 79% before I plugged in - hence using 3% to drive 7 miles at 7m/kWh - 3% of 30kWh = 0.9kWh

Now that BP have given up charging a £1.20 Connection Fee, I will be making this journey more often to charge for free at ASDA - so I will try to repeat the "self - charging" experience over the 7 mile journey.
Platinum White Pearl: e-driving green at last, on R17 Michelin Pilot Sport
A fan of One Pedal Driving max >>> and physical buttons
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londiniumperson
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Post by londiniumperson »

I think it's relatively common for some EV owners to track usage data in some form and like you I also keep extensive records. Initially I took photos at the start & end of every journey, but now I only do this at the start and end of each day that I use the car and record this in a spreadsheet along with the amount of every charge whether at home or at a public charger.

Thanks for bringing this up, if it had occurred to me then I definitely would have noticed because I usually do a couple of short journey's of under 2 miles each way most weeks as well as longer commutes.

What I can definitely confirm is that the data presented on the dash does not always align with my own charge data & miles driven. However I have no way to give a conclusive answer as to what the reason for this is because Honda don't provide any access to the car's data.

As for ASDA free chargers, they can't come soon enough for me because there's an ASDA just across the road from where I work & if I'm willing to walk the 1 mile round trip then I could leave my car there for a couple of hours and top the car up each day.
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
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advance2020
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Post by advance2020 »

Well I repeated the same journey today. Achieved 7.6m/kWh going 7 miles exactly.
It is downhill. Just checked the elevations. We're at about 620ft and ASDA car park is 235ft so that's a 385ft drop. Set off with 84% SoC showing, and 82% when I arrived. I had charged to 85% overnight, but had cleaned the car, so lost a little before setting off. Managed to charge up to 100% in just over an hour, and used 7% coming home in Sport mode. Why not, when the energy is free!
Platinum White Pearl: e-driving green at last, on R17 Michelin Pilot Sport
A fan of One Pedal Driving max >>> and physical buttons
milligoon
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Post by milligoon »

Stop hogging the local chargers you freeloader 🤣
Ex e owner
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