thankyouOB
Well-known member
hopefully on topic:
what is the kw of a bar?
1.67kw?
what is the kw of a bar?
1.67kw?
80% Charging???
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If you assume a Leaf with a relatively recent firmware, and agree that the last bar disappears shortly after you receive the low battery warning: (21 - 3) / 12 ~ 1.5 kWh. Note that this would be usable capacity as measured by dash instruments. We had other discussions where Phil mentioned that stored capacity was about 8% higher than what we see on the dash (~1.6 kWh). If you add charger losses, the energy drawn from the wall should be higher still (~1.7 kWh).thankyouOB said:
TonyWilliams
Well-known member
surfingslovak said:
And with all that said, the energy value of the fuel bars is variable based on battery temperature (which can be significantly different than ambient temperature) and also variable with battery degradation.
A cold battery can easily have over 10% reduction in capacity, and still show 12 fuel bars at a full charge. The same is true of the battery that is 50% degraded; it also will show 12 fuel bars, even though each is worth half of a new battery.
It is impossible to assign a singular fuel bar capacity number.
thankyouOB
Well-known member
thanks. I am pretty much thinking not aged battery in our SOCAL coastal ambient temperature range of 55-80.
TonyWilliams
Well-known member
thankyouOB said:
Except we have at least one instance of a car potentially delivered new with a degraded battery.
planet4ever
Well-known member
I find the number of bars useful as a "fuel gauge", but not as a driving efficiency gauge. As a fuel gauge, 5 bars is "half a tank", and 1 bar is "a quarter tank". But you don't need to know kWh/bar for that.
I fear that when you start asking for kWh/bar you are trying to use the bars to determine driving efficiency. But it is just too distracting to note mileage exactly at the point where you lose each bar, and mentally convert that to miles/kWh or some such measure. Far better to reset and use the dash or console m/kWh number for averages, and the dash bar chart or console pie chart for instant values.
I do wish the LEAF had something like the Prius display of mpg as a bar chart in 5-minute intervals.
Ray
I fear that when you start asking for kWh/bar you are trying to use the bars to determine driving efficiency. But it is just too distracting to note mileage exactly at the point where you lose each bar, and mentally convert that to miles/kWh or some such measure. Far better to reset and use the dash or console m/kWh number for averages, and the dash bar chart or console pie chart for instant values.
I do wish the LEAF had something like the Prius display of mpg as a bar chart in 5-minute intervals.
Ray
1.38 kWh/bar, from this formula:thankyouOB said:
(tripmeter / miles_per_kwh_lcd_display) / (starting_bars - ending_bars)
over 236 charge events.
Caveats:
- contingent on accuracy/repeatability of center display's mi/kWh figure
- this kWh figure is either "kWh extracted from battery" or "kWh delivered to motor" but definitely not "kWh from the wall".
Stoaty
Well-known member
Fits nicely with Mark Perry's statement on the recent webcast that a bar is 1.4 kWh.aqn said:
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Stoaty, was that the webchat from last week or one of Mark's videos perhaps? The 1.5 kWh I mentioned above is an approximation, obviously, but one that worked great for me. As Tony mentioned above, the segments on the battery gauge are unfortunately too fluid, and it's pretty difficult to figure out what they really mean in terms of energy with any degree of accuracy. Being an engineer, I like creating and tweaking models, especially ones that can be both practical and useful.Stoaty said:
I have to admit that I used Andy's empirical kWh/bar value before. It was one of the many things I tried, and I'm wondering why it appears to be consistently lower than what the models I was working on would predict. One of the rationales I considered was the low resolution of the battery gauge. Since each bar is about 8% of the displayed usable energy, I would expect about 4% error from a purely empirical value based on a readout from that display.
Personally, I've been using the reverse SOC meter and a Gid meter. Found both to work quite well. As to the recent discussion we had on the forum, I believe that the Leaf will protect a percentage of SOC, not an absolute value, and we might see different Gid values for LB and VLB warnings once some batteries have degraded far enough to warrant an adjustment.
Stoaty
Well-known member
Yes.surfingslovak said:
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Ingineer
Well-known member
As far as my experience suggests, the bars are not exactly quantifiable. They have hysteresis and weird lags.
On Saturday morning (for the BayLEAFs meeting), I had charged to 100% (read ~94% SoC) and then preheated via carwings for about 15 minutes. When I disconnected the charge cord and got in, I was showing ~89% SoC, yet I still had all 12 bars. I'm surprised the car lost about 5% SoC during preheat, as it usually doesn't. Either way, the bars didn't reflect any of it.
-Phil
On Saturday morning (for the BayLEAFs meeting), I had charged to 100% (read ~94% SoC) and then preheated via carwings for about 15 minutes. When I disconnected the charge cord and got in, I was showing ~89% SoC, yet I still had all 12 bars. I'm surprised the car lost about 5% SoC during preheat, as it usually doesn't. Either way, the bars didn't reflect any of it.
-Phil
Stoaty
Well-known member
It is possible that I remembered wrong. I was 99% sure that he answered the kWh per bar.surfingslovak said:
edatoakrun
Well-known member
Ingineer said:
Phil,
Someone with a LEAFSCAN (hint) could probably add quite a bit to this thread:
http://www.mynissanleaf.com/viewtopic.php?f=31&t=8549" onclick="window.open(this.href);return false;
I have been seeing some extreme deviations between expected, and actual, bar display and LBW/VLBW.
For brevity, I've mostly just posted the battery warning info from 100% charge, but I've also been logging for bar disappearance, and there seems to me the most likely explanation, is that the bar display and the LBW varies at close to the same level, for kWh use, from both a 80% and 100% initial charge, on my LEAF.
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Phil, thanks for that comment. I don't use preconditioning much, and I have missed this effect. To be fair, something similar was reported in the reverse SOC thread. Apparently, the charging time display can get a bit fuzzy as well when preconditioning is used. Although providing a usable energy estimate for battery bars is difficult and prone to error, the 1.5 kWh I quoted earlier worked for me, and several others. Obviously, your proverbial mileage can vary.edatoakrun said:
Edatoakrun, I reviewed the thread you mentioned, and I'm sorry to say this, but the methods you are using are just too weird for words. I recommend that you reset at least one of your energy economy meters, as was suggested before. Furthermore, it would be worthwhile to borrow a Gid meter as well. To be fair, I saw turtle mode earlier than I would have expected on a steep ascent once, but I was not properly instrumented then. Although I mentioned it on the forum, I don't think that my concern was valid. I'm afraid that something similar can be said of your recent observations.
edatoakrun
Well-known member
surfingslovak said:
Why don't you state exactly what you think is "weird" on that thread, and maybe I can explain further.
Ingineer
Well-known member
Since the overall biggest problem getting accurate capacity information in the Leaf is it's lack of a good coulomb counter, we are stuck with the best Nissan could do with what hardware they decided to use. (Of course if we wanted to install a lab-grade calibrated kelvin current shunt, we could solve that problem, but I think this would be expensive and difficult, not to mention dangerous!)
Once you understand that the hall-effect device used in the Leaf suffers the most inaccuracies at low levels, you can easily understand why there will be wide reported SoC (and thus Gid) variation from final minutes of charging, as well as during pre-heat/cool. This is because the overall current in/out of the battery is low, which is where the hall-effect is prone to error/drift. This is compounded by high-frequency variation in current from both the PTC heater and the on-board charger.
So after charging and pre-conditioning is over, if you allow the Leaf to rest for a few minutes, then cycle power, the battery ECU will do a table lookup correction and you'll see SoC jump. The watt-hour figure (Gids) doesn't seem to jump though, (or at least as often) as I think they intentionally stop it from changing in this way so you don't see your GoM jump too.
-Phil
Once you understand that the hall-effect device used in the Leaf suffers the most inaccuracies at low levels, you can easily understand why there will be wide reported SoC (and thus Gid) variation from final minutes of charging, as well as during pre-heat/cool. This is because the overall current in/out of the battery is low, which is where the hall-effect is prone to error/drift. This is compounded by high-frequency variation in current from both the PTC heater and the on-board charger.
So after charging and pre-conditioning is over, if you allow the Leaf to rest for a few minutes, then cycle power, the battery ECU will do a table lookup correction and you'll see SoC jump. The watt-hour figure (Gids) doesn't seem to jump though, (or at least as often) as I think they intentionally stop it from changing in this way so you don't see your GoM jump too.
-Phil
LEAFfan
Well-known member
Ingineer said:
Yeah, sometimes when I QC (to 100%), I will have 12 full bars (13-14mi.on top bar), but my gauge will only show 86% or so and it will only catch up at the lower end.
When I pre-heated in the winter for 5-10 mins., I always lost SoC.
Ingineer
Well-known member
Seems like any pre-heat less than 20 mins is a net loss. I think you need a good 30 mins to recoup the loss. (PTC draws > OBC output) The cabin has to heat up until the PTC heater drops power so the battery can recharge.
Still infuriating that you have no idea with Nissan's instrumentation.
-Phil
Still infuriating that you have no idea with Nissan's instrumentation.
-Phil
RegGuheert
Well-known member
That actually makes good sense to me. For such a crude measurement as 12 bars, I'm glad that these things don't flick on and off all the time!Ingineer said:
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