Battery Percent Indicator

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bdgriner

Member
Joined
Feb 24, 2016
Messages
12
Location
Birmingham Alabama
I’ve been driving EVs for 5 years and had my most recent Leaf for 2. I understand the miles remaining is very inaccurate but suspect the percent remaing isn’t either. I rountinely Drive 75 miles a day to and from work and get the second low battery alarm and blank screen for miles or battery remaining. I have the 30KW Leaf and when I recharge, I get between 19 and 21KW on my charger. The question I have is why am I getting an alarm for 10% remaining when I should have 30% left? It’s one of the first 30KW models and wonder if something is not set right in the software? Anyone else seen this? Any suggestions?
 
bdgriner said:
I’ve been driving EVs for 5 years and had my most recent Leaf for 2. I understand the miles remaining is very inaccurate but suspect the percent remaing isn’t either. I rountinely Drive 75 miles a day to and from work and get the second low battery alarm and blank screen for miles or battery remaining. I have the 30KW Leaf and when I recharge, I get between 19 and 21KW on my charger. The question I have is why am I getting an alarm for 10% remaining when I should have 30% left? It’s one of the first 30KW models and wonder if something is not set right in the software? Anyone else seen this? Any suggestions?
Battery capacity is measured in kWh not "KW". The amount of energy that comes out of your "charger" (likely an EVSE w/no charger because for level 1 and 2 AC charging, the charger is on-board the car) and "wall" is also measured in kWh.

I can't speak for the 30 kWh Leaf since I don't have 1, but on the '13 Leaf, as I stated at http://www.mynissanleaf.com/viewtopic.php?f=31&t=17895, LBW (1st warning) used to sound at ~17-18% and VLBW (2nd warning) at 7-8% per the car's dash display. Those values have gone up slightly as the battery has degraded (and I have a different '13 Leaf now). The gid values (you need something like Leaf Spy to see them) at http://www.mynissanleaf.com/viewtopic.php?p=387707#p387707 seem correct for 24 kWh Leafs. Can anyone chime in on what gid and dash display values they sound on 30 kWh Leafs?

What value on the dash display do LBW then VLBW sound at? How many capacity bars have you lost, if any? http://www.electricvehiclewiki.com/File:Scott_3_bars_s.jpg is a 3 bar loser.

Also, not all the energy coming out of the wall makes it into the battery. And, not all 30 kWh are usable. Nissan leaves some portion at the top and bottom in accessible. IIRC, TonyWilliams has asserted 30 kWh Leaf has about 26.5 kWh usable, on a new battery. Don't know how accurate that is, but that's likely close.

Also, as the battery degrades, since it will have less capacity, if you charged from 0 to 100% on such a degraded battery, less energy will come out of the wall than vs. a new one.

If you really want to have a better idea of what's going on, you should get Leaf Spy. If you want to see why it can be useful, watch this 11 minute video at https://www.youtube.com/watch?v=cgE8lmySdMI. If the talking to too slow or repetitive, use the gear icon on PCs or Macs to increase the playback speed.

Background info on charger vs. EVSE at:
http://www.mynissanleaf.com/viewtopic.php?p=262630#p262630
http://www.sae.org/smartgrid/chargingprimer.pdf
http://www.sae.org/smartgrid/chargingspeeds.pdf
https://openev.freshdesk.com/support/solutions/articles/6000052074-basics-of-sae-j1772
 
On the 2016 Leaf the LBW warning is fixed at 50 GID's (About 4KWH remaining) VBLW is fixed as well at about half the value of LBW. As the battery loses capacity over time, the percentage where the LBW warning occurs rises. I've found that the percentage gauge seems to be reasonably accurate while the guess-o-meter becomes more accurate the closer you are empty. When new, my car hit LBW at 13%. Now with two bars gone, LBW hits at about 18%. Hope that helps.
 
The goal is to protect against any cell going too low, which is bad for the cell. Or even worse, polarity reversal which is almost certain death for the cell and can escalate into a catastrophic failure of the entire pack, and dangerous consequences. It's the weakest cell-pair that drives the low battery warnings, if I'm not mistaken. So you cannot always expect the warnings to correlate with an exact watt-hours remaining in the pack.

With our 2012 I had long been practicing the 80% charge method, and then happened to do an extended drive. Once at LBW, the power remaining dropped very quickly and I was lucky to make it home. I chalked it up to a lack of cell-balancing. The next 100% charge spent a lot of time in balancing mode and I made it a practice after that to do a full 100% charge on a regular basis. I'm rambling, but it illustrates the nature of LBW as a low cell-pair voltage threshold rather than a stored-energy-remaining threshold. The two are related of course, but not necessarily proportionally.
 
johnlocke said:
On the 2016 Leaf the LBW warning is fixed at 50 GID's (About 4KWH remaining) VBLW is fixed as well at about half the value of LBW. As the battery loses capacity over time, the percentage where the LBW warning occurs rises. I've found that the percentage gauge seems to be reasonably accurate while the guess-o-meter becomes more accurate the closer you are empty. When new, my car hit LBW at 13%. Now with two bars gone, LBW hits at about 18%. Hope that helps.
Interesting, so the gid values where LBW and VLBW sound at for the 30 kWh Leaf are or are basically identical to that of 24 kWh Leafs.
 
bdgriner said:
Big thanks. This gives me the info i need to research further into the issue. I will provide an update in a few weeks with my findings.
Until you get Leaf Spy working, you can at least tell us how many capacity bars you've lost and what % SoC on the dash display are LBW and VLBW sounding at.
 
I haven’t lost any capacity bars on my display. I’ve been making the same drive since I bought the car new 19 months ago and ~90% of the time have the LBW (first alarm ) and depending on my driving style, traffic and temp if I get the VLBW (second alarm) (~50%). I’ve never questioned the overall charge until recently when I went back and looked over my ChargePoint history and see between 19 and 21 KWH recharges.

The LBW comes in at 15%. The VLBW you can’t tell %SOC since the reading is unavailable. The LBW warning message covers it up. It seems like the VLBW alarms at 9 miles left and then the miles remaining goes away. You have no readings then. Most miles I’ve driven with the VLBW is about 3 miles.

Im traveling this week so That’s why it’s taking a little while to get the info with Leaf Spy.
 
bdgriner said:
The LBW comes in at 15%. The VLBW you can’t tell %SOC since the reading is unavailable. The LBW warning message covers it up.
What do you mean by that? You should be able to press 1 of the 4 buttons in the cluster of 4, probably the upper left, to clear it so that the % SoC screen is back up.

However, at some point, it's likely the numeric % SoC will change to - - - % (I've personally run into this and I've seen numerous folks post pictures of it). That's when you're flying really blind w/o a tool like Leaf Spy.
 
I have my Leaf Spy working today. It was really easy to get working. My hats off to the developer. They did a great job.

I now have to start collecting data. My first screen copies I cant figure out how to post and reading the FYIs, looks like I will need to get permissions. Anyway, the first set of data taken today have me concerned. I collected this data between the two low level alarms and did a quick 3 mile test drive. The two numbers that had me concerned are SOH=67% and HX= 61.55% . GIDs is 24.1%. I'm charging the car and put a few miles on it to collect more data.

Any suggestions on a good website that provides more detail explains of these values? The help screen on the app is a starting point but was hoping to find more detail.
 
This site is probably the best place to learn about things like SOH (which is effectively equivalent to remaining battery capacity as a percentage) and Hx (more like a momentary snapshot of the SOH - Hx varies more over short periods than does SOH). Look for the Leafspy topics here.
 
bdgriner said:
The two numbers that had me concerned are SOH=67% and HX= 61.55% . GIDs is 24.1%.
...
Any suggestions on a good website that provides more detail explains of these values? The help screen on the app is a starting point but was hoping to find more detail.
http://www.electricvehiclewiki.com/Glossary

For me, I don't care about gid %. I don't know the denominator. I'd rather look at the actual number of gids.

Regarding SOH and Hx, see http://www.mynissanleaf.com/viewtopic.php?p=497564#p497564. Turbo3 is the Leaf Spy author. Nissan AFAIK has never released any public documentation on traffic on the CAN bus or anything that Leaf Spy retrieves.

The most comprehensive and up to date docs are in the app help. You can email the dev for a copy of it in PDF form.
bdgriner said:
I haven’t lost any capacity bars on my display.
This is impossible if those SOH and Hx values are correct. You are probably down 2 or 3 bars. Again, it's the thinnest bars all the way on the right. http://www.electricvehiclewiki.com/File:Scott_3_bars_s.jpg is an example of a fully charged 3 bar loser. Please check again. How many capacity bars do you have visible, including the red ones?

How many gids (numeric not %) do you get to on a full charge?

bdgriner said:
I’ve been driving EVs for 5 years and had my most recent Leaf for 2.
...
I have the 30KW Leaf and when I recharge, I get between 19 and 21KW on my charger.
...
It’s one of the first 30KW models
As I said, your unit usage is incorrect. Battery capacity is measured in kWh, not "KW". What comes out of the wall is over time is also measured in kWh.

kW and kWh are very different metrics. It's the same as confusing gallons with horsepower. Think of kW = horsepower, kWh = gallons.

If one charges at 1 kW (or 1000 watts) for 6 hours, 6 kWh came out of the wall. If it's at 6 kW for 1 hour, it's also 6 kWh. If it's 1 watt for 6000 hours, it's also 6 kWh.

One pays for electricity at home in cents per kWh. There are a few utilities w/residential plans where they not only bill per kWh but also have demand charges, but that's rare and complicates calculations. (Demand charges aren't unusual on many commercial plans.)

1 hp = ~0.746 kW. And, many .gov sites say 1 gallon of gasoline has 33.7 kWh of energy content.

You have a '16 Leaf SV or SL? Build month? That's on the driver's side door sticker.

http://www.mynissanleaf.com/viewtopic.php?p=508397#p508397 who also used incorrect units is down 3 bars on his 30 kWh Leaf.

ydrape said:
<span>You can also look at this site for a complement to <a href="http://www.amazon.com/Turbo3-Leaf-Spy-Pro/dp/B00PMLTPN0/?tag=myelecarfor-20&" class="interlinkr" target="_blank">Leaf Spy Pro</a> Help file.</span>

http://www.electricvehiclewiki.com/Leaf_Spy_Pro
It is unfortunately out of date compared to the app but it isn't useless.
 
Big thanks Cwerdna. You gave me the thread with the issue I’m having with my 30 kWh battery pack. The key info is below. My question know is at what point has the battery degraded to the point of needing replacement?

2016 SV with build date of 10/2015

Fully charged, LeafSpy says 19.1kWh capacity. Significantly below name plate of 30 kWh. (Understand it was never 30 kWh but suspect is over 25% loss already)


AHr: 52.96
SOH: 66% 394.77V
Hx: 60.83%
odo: 27k
3 QCs
823 L1/L2s
242 GIDs
 
johnlocke said:
On the 2016 Leaf the LBW warning is fixed at 50 GID's (About 4KWH remaining) VBLW is fixed as well at about half the value of LBW.
Do these kWh values include the inaccessible battery reserve ?
 
bdgriner said:
Big thanks Cwerdna. You gave me the thread with the issue I’m having with my 30 kWh battery pack. The key info is below. My question know is at what point has the battery degraded to the point of needing replacement?

2016 SV with build date of 10/2015

Fully charged, LeafSpy says 19.1kWh capacity. Significantly below name plate of 30 kWh. (Understand it was never 30 kWh but suspect is over 25% loss already)


AHr: 52.96
SOH: 66% 394.77V
Hx: 60.83%
odo: 27k
3 QCs
823 L1/L2s
242 GIDs
No prob. I haven't been able to respond very promptly as I'm on vacation in Japan so there's a considerable time difference and my priority here is to sightsee/do things unique to Japan (my posts about Tokyo Motor Show/Japan commenced at http://www.mynissanleaf.com/viewtopic.php?p=509704#p509704) vs. being holed up my hotel room.

First off, I don't put any value in assertions that a pack has xx.xx kWh of capacity based upon Leaf Spy's calculated figures and default of 77.5 watt hours per gid. See http://www.mynissanleaf.com/viewtopic.php?p=472552#p472552 and http://www.mynissanleaf.com/viewtopic.php?p=476092#p476092. Nissan does not let the user access all 30 kWh anyway. It's probably around 27 kWh on a new battery that's user accessible.

From your SOH figures, you're probably down 3 capacity bars. You need to be down 4 capacity bars before the 8 year/100K capacity warranty (on 30 kWh Leafs) to get it replaced . Again, please refer to the thinnest bars all the way on the right. http://www.electricvehiclewiki.com/File:Scott_3_bars_s.jpg is a 3 bar loser and that's what yours probably looks like now.
 
SageBrush said:
johnlocke said:
On the 2016 Leaf the LBW warning is fixed at 50 GID's (About 4KWH remaining) VBLW is fixed as well at about half the value of LBW.
Do these kWh values include the inaccessible battery reserve ?
I couldn't care less about the what claimed kWh values are. See my earlier post.

On 24 kWh Leafs, it was asserted at http://www.mynissanleaf.com/viewtopic.php?p=387707#p387707
TomT said:
Since LBW and VLBW occur at an absolute fixed energy level (49 and 24 Gids, respectively)
That seems about right, from my experience.

It seems like there's some wonkiness with gids near the top and esp. near the bottom of the battery anyway.
 
SageBrush said:
cwerdna said:
I couldn't care less about the what claimed kWh values are.
Whatever. Just assume default Gid/Wh
Sure. I suspect most Leaf Spy users don't know about the setting and thus are using the default.

My issue is that with the default of 77.5 watt-hours/gid or whatever other value, we have no idea if the resulting kWh value is accurate at all. Unless you can tell me that Nissan has officially blessed that constant or given us conditions where the result is accurate (e.g. range of gid values where it's valid, battery temperature, battery condition, after certain things have been done or not done to the battery, etc.)...

It really bothers me that so many people are doing so much reading into and inference of values that Leaf Spy (e.g. gids, gids * Wh/gid, SOH and Hx, etc.) renders despite the fact that AFAIK, Nissan has never released any public documentation on them nor acknowledged any of them. Sure, we can compare notes, but to make assertions like "my battery holds x kWh" or 85% SOH must == 15% capacity loss, I'm not that comfortable with. Is it approximately right? Probably, most (?) of the time. Is it exact? Probably not, esp given the numbers move around a bit and can be manipulated a bit, as well.
 
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