Time to charge to 100% - Renault Z.E. Forum
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post #1 of 12 (permalink) Old 11-25-2013, 03:47 AM Thread Starter
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Time to charge to 100%

Since the cold weather set in I've been logging how long it has taken to charge from approx. 25% up to 100%. My figures refer to the 10A charging cable.

Over 5 charges the figures have varied from 7hrs. 7 mins. to 7hrs. 39mins. while the miles being "replenished" have varied from 64 down to 55.

The latest (sixth) charge has been a surprise. Using the car in a daytime temperature of around +6 the car only achieved 46 miles on a three quarter charge with an estimated 18 miles remaining, giving a low total of just 64 miles. The surprise came with the charge (at a night-time temperature of +4) which completed in a mere 6h 38 mins., an hour less than expected.

My only explanation is that the charge rate is more influenced by mileage gone than by percentage of battery used or by ambient temperature. Does this make sense?
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post #2 of 12 (permalink) Old 11-25-2013, 04:41 AM
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RE: Time to charge to 100%

Quote:
Originally Posted by pauledg
Since the cold weather set in I've been logging how long it has taken to charge from approx. 25% up to 100%. My figures refer to the 10A charging cable.

Over 5 charges the figures have varied from 7hrs. 7 mins. to 7hrs. 39mins. while the miles being "replenished" have varied from 64 down to 55.

The latest (sixth) charge has been a surprise. Using the car in a daytime temperature of around +6 the car only achieved 46 miles on a three quarter charge with an estimated 18 miles remaining, giving a low total of just 64 miles. The surprise came with the charge (at a night-time temperature of +4) which completed in a mere 6h 38 mins., an hour less than expected.

My only explanation is that the charge rate is more influenced by mileage gone than by percentage of battery used or by ambient temperature. Does this make sense?
Not sure if it makes sense, but I have been logging my mileage against charge time since I got connected to ZE services. The majority of the time I use the 15A charge. the time is the point at which I get the end of charge notification. Details below if you want to analyse the data

Mileage Amps Hours Mileage Miles/kWh
4520 15 5.90
4542 15 2.80 22 2.46
4578 15 3.57 36 2.76
4578 10 0.93 0 0.00 (testing end of charge consumption)
4592 15 2.57 14 1.72
4629 15 1.83 37 2.90
4636 15 3.00 7 1.99
4654 15 2.43 18 2.36
4668 15 2.40 14 1.86
4709 15 3.98 41 3.10
4745 15 3.97 36 2.74
4771 15 3.62 26 2.18
4827 15 5.55 56 2.97
4842 15 2.07 15 2.37
4860 15 2.43 18 2.36
4890 15 0.68 30 2.89
4900 15 0.98 10 1.89
4922 15 6.27 22 1.87
4961 15 4.77 39 2.43
4999 15 4.52 38 2.51
5046 15 5.18 47 2.68
5077 15 3.90 31 2.40
5122 15 1.02 45 2.26
5126 15 5.40 4 1.96
5166 15 1.10 40 2.42
5167 15 0.27 1 1.92
5177 15 5.27 10 1.74
5226 15 2.97 49 2.60
5249 15 5.15 23 2.48
[hr]
Sorry Paul just noticed you were only looking at charge time to 100%. I have included that info now so you can factor out partial charges

Mileage Start % Finish % Amps Hours Mileage Miles/kWh
4520 2 100 15 5.90
4542 52 100 15 2.80 22 2.46
4578 37 99 15 3.57 36 2.76
4578 99 100 10 0.93 0 0.00 (testing end of charge cons.)
4592 63 100 15 2.57 14 1.72
4629 41 72 15 1.83 37 2.90
4636 59 100 15 3.00 7 1.99
4654 69 100 15 2.43 18 2.36
4668 67 100 15 2.40 14 1.86
4709 27 100 15 3.98 41 3.10
4745 33 100 15 3.97 36 2.74
4771 41 100 15 3.62 26 2.18
4827 10 100 15 5.55 56 2.97
4842 76 100 15 2.07 15 2.37
4860 66 100 15 2.43 18 2.36
4890 53 64 15 0.68 30 2.89
4900 36 56 15 0.98 10 1.89
4922 7 100 15 6.27 22 1.87
4961 29 100 15 4.77 39 2.43
4999 27 100 15 4.52 38 2.51
5046 16 100 15 5.18 47 2.68
5077 43 100 15 3.90 31 2.40
5122 7 26 15 1.02 45 2.26
5126 12 100 15 5.40 4 1.96
5166 24 43 15 1.10 40 2.42
5167 37 45 15 0.27 1 1.92
5177 10 100 15 5.27 10 1.74
5226 6 63 15 2.97 49 2.60
5249 16 100 15 5.15 23 2.48
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post #3 of 12 (permalink) Old 11-25-2013, 07:00 AM Thread Starter
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RE: Time to charge to 100%

Thanks for that, Electricdream. I'm just finishing off my Xmas cards (WOW) then I'll dive into your figures and see what I can work out.

I'm still surprised by your m/kwh figures compared with mine. I do wonder whether the dashboard readout is accurate.
To take one example, one of your charges from 16-100% calculated out at 2.68.
On a similar trip in my car, 25-100% calculates out at 2.84 yet the car's readout was a whopping 3.85.
I'll check on the next charge and see if there's a similar high figure being shown.

Right. the mystery deepens! On today's charge:
Miles used 46
Battery used 75%
calculated kwh used 16.5
m/kwh 2.79
dash readout 3.65
and the dash reckons I only used 12kwh.

This has really confused me. Why would the car show battery down to 25% but usage of only 12kwh? Now I have not a clue as to what is going on. Do I have a battery capacity of only 16kwh? If so how do I achieve high mileages in warmer weather? Maybe the battery meter lies in cold weather? Anyone got any ideas - how about someone brave enough to run to empty to check?
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post #4 of 12 (permalink) Old 11-25-2013, 08:50 AM
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RE: Time to charge to 100%

I seem to be settling out on average 2.5m/kWh or 55 mile range for a full charge.

I have not really paid much attention to the dash figures. The info I get from ZE services is all I am using to compile my figures. The equation I use (when charging to 100%) for consumption is [(Stop Time-Start Time-0.7) x 3.6 +1.4]. For interest, the 0.7 accounts for the 42 mins associated with the 'constant voltage' phase at end of charge. I have this at a FIXED consumption of 1.4kWh for the 42 mins (hence the 1.4 in the equation).

The range estimation that I get at end of charge seems pretty much on the button. I am assuming the estimation is the same as on the dash but I have not checked to confirm this.
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post #5 of 12 (permalink) Old 11-25-2013, 09:07 AM
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RE: Time to charge to 100%

Quote:
Originally Posted by pauledg

This has really confused me. Why would the car show battery down to 25% but usage of only 12kwh? Now I have not a clue as to what is going on. Do I have a battery capacity of only 16kwh? If so how do I achieve high mileages in warmer weather? Maybe the battery meter lies in cold weather? Anyone got any ideas - how about someone brave enough to run to empty to check?
Could it be that the dash display is ONLY logging the consumption drawn by the motor (i.e the power to actually drive the wheels)

I know that would be a pretty ridiculous thing to do but I reckon your 'missing' 4.5kWh could easily be what is being used to keep you from freezing to death!!
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post #6 of 12 (permalink) Old 11-25-2013, 11:26 AM Thread Starter
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RE: Time to charge to 100%

Yes, that thought occured to me too. If so the figures are pretty meaningless. So you could be right!
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post #7 of 12 (permalink) Old 11-25-2013, 12:25 PM
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RE: Time to charge to 100%

FWIW; I have pretty much stopped watching the M/kWh gauge during this colder weather when running the heater. I don't believe it includes the heater use. It is the current into the motor.

That being said, every once in a while it seems to read worse when I run the heater.

Now, there could well be reasons for that - the battery runs less efficiently when a larger current is drawn. But if the heater is running, then that adds to the traction current drawn and both then become less efficient.

Some other reasons for reduced range may well be that the battery has protections built in when it gets colder, and excludes using more of the extremes of the battery. I deliberately try to avoid full charges, but have been doing that more recently because otherwise the pre-heat doesn't work. But it is entirely possible that, for example, 100% charged is actually 80% 'real' battery capacity, say from 5C to 30C, and outside those bounds the software drops accessible battery capacity to 70%. (just illustrative figures for what it might be doing).

As Paul uses his less frequently than us, it might well be that his is undergoing a more thorough cold soak and getting to lower temps. I imagine that heat generated in my battery on the drive I am about to undertake now will mean there is still a little warmth in the battery tomorrow (because the battery is better isolated in the boot than in most other EVs). However, leave it for a few days and it'll lose all that heat.

The above are just thoughts and I don't know for sure on any of it. The other option is that your battery capacity is declining!! It's a case of 'when', not 'if', and statistically each of our batteries will degrade at different rates, maybe even some have rouge cells that will cause this to happen early. I don't think there is any reason to believe this, though, until summer time. You can't tell what the heck is happening to the juice in the battery whilst it is being squandered into a resistive heating system!

(I still think 2M/kWh sucks! - I got around 3.5M/kWh today, based on SOC meter, with sufficient heat getting to my feet (as described in the other post)
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post #8 of 12 (permalink) Old 11-26-2013, 03:44 AM Thread Starter
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RE: Time to charge to 100%

All very confusing, but at least we're keeping our brains active, that should generate some surplus heat!

On my trip to Oxford yesterday (24.5 miles round trip) the car achieved an average 4.0m/kwh, if the figures are to be believed. On that basis the current charge should take me 134.75 miles. if it does, I'll let you know.
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post #9 of 12 (permalink) Old 11-26-2013, 01:30 PM
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RE: Time to charge to 100%

Quote:
Originally Posted by pauledg
On that basis the current charge should take me 134.75 miles. if it does, I'll let you know.
Not sure what you're saying/calculating, here, Paul.

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post #10 of 12 (permalink) Old 11-26-2013, 01:54 PM Thread Starter
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RE: Time to charge to 100%

134.75? Yeah, silly me! I wonder where the **** I got that figure too - it's nonsense. Try 88.

The kwh dashboard readout does NOT include ancillaries including heater - I should have read the manual. So the m/kwh figure probably doesn't either.

(God! If I have to correct any more of my mistakes I'll start to get worried the cold has got to me.)
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