Replace Miles Range Number on Dash with kWhr Remaining

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Tyz

Member
Joined
Jun 2, 2011
Messages
8
Location
Walnut Creek
Please provide a software upgrade that gives me the option (assuming some people will still want the miles range guesstimate) to replace the miles range number on the dash with the estimated usable kWhr remaining. The units line below the large numerals would read "kWhr" instead of "Miles" or "Km". Allow me to select this option where I now select units (e.g., miles versus kilometers).

This would give me a significantly more accurate estimate of remaining usable energy than I can get from counting bars on the analog charge/SOC gauge (24 divisions instead of 12 - give me tenths of a kWhr if feasible). And I know the number at a glance instead of having to stop, count bars, and multiply by 2. And it continues to provide exactly the information I need even as the battery capacity declines over time, or when I install new and hopefully better batteries in the future.

Thanks
 
I'd rather just have a 2-digit SoC percentage, and I wouldn't want to lose the range estimate. The range estimate is useful if you understand what it's telling you. I wouldn't mind the option to switch between the two, however.
 
I see many people asking for a percentage number. But then to get the kWhr remaining you have to multiply by the battery capacity which seems to be uncertain even in a new vehicle, and varies over the life of the battery. What am I missing? But each to their own, so add both options, so we can then choose between miles, kilometers, kWhr, or percent.
 
DaveinOlyWA said:
the more information the better. i welcome another gauge but not to replace one that is already there
Exactly.

They should show SOC/Kwh and also get better at giving a decent RangeRemaining estimate.

BTW, George and some others claim that Volt estimate is quite accurate. Wonder what exactly they do.
 
evnow said:
DaveinOlyWA said:
the more information the better. i welcome another gauge but not to replace one that is already there
Exactly.

They should show SOC/Kwh and also get better at giving a decent RangeRemaining estimate.

BTW, George and some others claim that Volt estimate is quite accurate. Wonder what exactly they do.

ya, easy to say when we cannot verify it. i "could" say the same thing and to be honest with you, i dont feel that the range estimate is really that bad.

i start in the morning, it says i have 112 miles but i know that to more likely be 85 miles but i know why it says 112 miles and so do most of us here but we insist upon some sort of validation or explanation as to why it drops to 95 miles left when only 6 miles from home as we climb that hill.
 
It would be difficult to add additional displays to the current DTE meter because there is no button to use for controlling the display. However the trip computer button (top left in the cluster of 4 to the left of the steering wheel) already selects among several displays above the steering column. It should be easy for them to add one more display showing SOC% and kWh.
evnow said:
BTW, George and some others claim that Volt estimate is quite accurate. Wonder what exactly they do.
Two things I've read they do for sure are: have a smaller battery, and use a smaller portion of the battery's capacity.

One more thing they could do is use a bit of that extra reserved battery capacity to make up for mis-estimates. That is, if the battery is depleting faster than the computer originally told the driver to expect, then use a few percent more of the hidden reserve. If the battery is depleting slower than originally expected, then use a few percent less of the capacity.
 
walterbays said:
One more thing they could do is use a bit of that extra reserved battery capacity to make up for mis-estimates. That is, if the battery is depleting faster than the computer originally told the driver to expect, then use a few percent more of the hidden reserve. If the battery is depleting slower than originally expected, then use a few percent less of the capacity.
From what we know, they don't do that. It was infact one of the things various people suggested they should do ...
 
While I'm certain they could change the number readout with a software update, changing the Km/Miles would be problematic. I don't believe those are LCD read outs but rather masks in front of an LED. They could maybes turn them off, but that's about it. Same goes for showing tenths, their number readout may not have segments for decimal places... But they ABSOLUTEY could do it on the Energy Screen on the center console.
 
An accurate SOC percentage readout is an essential piece of equipment that should have been in place from day one.
 
An "accurate" value is the difficult part.

Displaying the "accurate" info would not be difficult, IF we had it ... but we do not.

The LEAF's own internal "Probable-SOC" value (approx. 0 to 281) is displayed by our SOC-Meter, but it can still be misleading, especially in its representation of the low-battery, usable-energy reserves, I believe.
 
Why would it not be accurate? My conversion has a hall effect sensor with temperature compensation that counts amp hours in and out of the pack and is very accurate.
 
How do you set the zero-point with the LEAF's (or your) battery technology?

The one lowest-capacity cell determines where the "zero" is.

Unfortunately, that cell can change from time to time,
especially as cell-equalization changes.
 
By what mechanism would absolute cell capacity change? It certainly does not change in my pack, my smallest cell 2 years ago is still my smallest cell today. Additionally the cells in the LEAF should be even more closely matched for capacity than my cells so variations will be very small. To protect the pack Nissan, and I, do not use the actual total capacity of the pack so the slight variations between cells don't matter. The gauge counts amp hours for the entire pack, not just a single cell. Using a 0-100% charge gauge shows actual pack capacity, not range guesstimates, or a series of bars with poor resolution.
 
FrankS said:
Please show show SOC/Kwh "somewhere" and allow us to turn that guesstometer off...
Based on a very small sampling of data recorded by a handful of owners this summer, it seems like one SOC point corresponds to about 72Wh. The sample if very small and we don't know how the ambient temperature and other factors would play into this figure. However, on a conceptual level at least, it would be possible to build another guessometer. One potential approach would be to multiply the MPK gauge number with the number of SOC ticks and apply an Wh multiplier. The obvious question here is, whether this sort of range prediction would be any better than Nissan's. I admit that I have been doing this mental math a lot lately, except that I don't have the SOC meter. I used the 1.5kWh per battery gauge bar approximation instead and this method seems to work well enough and reconciles with Tony Williams' range chart. On several occasions, I caught myself calculating a number only to realize that the guessometor was already showing it. It could be, that Nissan's masterpiece is better than we think. It's just a bit erratic.
 
How would Nissan handle the discharging of selected cels during equalization?
Easily, the small amount of charge that is dissipated when charge to the smallest cells is bled off during equalization might not even register, or 100% SOC is registered when any shunting begins. Pack capacity can never be more than the capacity of the smallest cell, or paralleled module. In reality any "balancing" between cells should be a rare occurrence. I run without any automatic balancing with my cells and have only done one manual rebalancing of my pack, and only to increase the accuracy, not because it really needed it. Most of us with a reasonably well matched pack of LiFePO4 cells have seen very little need for balancing so far. As far as I can tell any well matched pack of cells that avoid max charging and max discharging should need little to no balancing.
 
JRP3 said:
How would Nissan handle the discharging of selected cels during equalization?
Most of us with a reasonably well matched pack of LiFePO4 cells have seen very little need for balancing so far. As far as I can tell any well matched pack of cells that avoid max charging and max discharging should need little to no balancing.

Why do you think that at least two instances that I'm aware of, when the battery gets down to about 8-10% remaining SOC (based on how we're measuring %), the car has quickly gone to turtle mode (about 1.4% remaining).

Gary has thought that might be a cell balance issue. Is there something else that can do that?
 
I think it's a combination of a less than accurate display of SOC, ("about 8-10 percent" is not accurate), and a poor range estimating algorithm that forces the car to shut down "just in case". The other possibility, which would be really bad if true, is that the balancing of the cells at the top when charging, unbalances them so much at the bottom that some show extreme low voltage which signals the shut down. That would mean the pack was not well matched for capacity at the factory, which I highly doubt. I run my pack bottom balanced and simply stop charging when my smallest cell gets around 95% full. Bottom balancing means that no single cell will be driven too low during a deep DOD event when driving. The logic is that when driving I could push a few hundred amps through a discharged cell, while when charging it's only 20 amps or so into an almost fully charged cell. With closely matched cells it really doesn't matter much if you top or bottom balance, especially if you keep the top and bottom SOC ranges off limits, which I assume Nissan does by preventing 100% charge or discharge. I can buy cells grouped within 1% of each other as a private individual, Nissan should be able to do better.
 
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