Loss of Battery Capacity Over Time - Page 3 - 2018 Honda Clarity Forum
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post #21 of 26 (permalink) Old 10-26-2020, 12:30 AM
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And actually a float’s position on a vertical rod when measured is also a guess and in some cases not a very accurate one.
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post #22 of 26 (permalink) Old 10-26-2020, 12:33 AM
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Just found this website tonight as I’m researching my substantial range decrease. Live in MN with 55K miles on my ‘18 Clarity. I was lucky to get 40 EV miles this summer and great numbers the past two. Working from home cuz of Covid, it wasn’t that big of deal since I was barely driving 40 miles a day. Now I’m seeing trips barely clearing 35 miles before the gas kicks in. Oh, and driving no more than 55-60 mph.

Great info so far. Will push to get battery tested and also look at the service bulletins.

We have a ‘13 Volt too with 125K miles on it and the degradation has been minimal, I’m really frustrated so happy to see so many helpful posts.
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post #23 of 26 (permalink) Old 10-26-2020, 02:57 AM
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And actually a float’s position on a vertical rod when measured is also a guess and in some cases not a very accurate one.
I don't think I would say that a gas gauge is guessing. It is an instrument taking a reading. Like any instrument the accuracy depends on the particular instrument. You wouldn't say that a speedometer is guessing how fast you are going. It is taking a reading, with several variables that can affect its accuracy.

An EV range estimator on the other hand has to at least partially guess, because it has no way to know what the conditions will be on your next trip. It starts with an instrument reading of the SOC, then it looks at data history for recent trips to calculate what was the average miles per kWh on those trips, perhaps weighted towards the most recent trip. But after that it has to essentially guess what the conditions will be on your next trip. Will it be uphill or downhill, 70 mph or 40 mph, 85 degrees Fahrenheit or ten below freezing. Even though it knows the current temperature that doesn't help because it has no idea when your next trip will start, your next trip might be in one minute or in one week. And how will the car be loaded, just you, or the whole family and the husky and all of your luggage and a 50 lb sack of dog food for the husky. You may know some or all of that information, but the car doesn't, so it guesses based on your most recent trips. Or to be more accurate it "guesses" that your next trip will be under similar conditions as your most recent trips. Gas gauges don't do any of that, they just take a reading and report it, with the accuracy depending on the instrument.

Future EV range estimators will probably get more sophisticated and factor in the current planned route including speed, topography, predicted weather along the route including wind direction (based on your input of estimated departure time). Tire pressure (which affects range), maybe even the current weight of the car. But to make it really accurate you would need to be able to input what your intentions are in regards to the speed limit, because going 15 mph over the speed limit will have a big impact on range. But I kind of think car makers are not going to have a setting in their NAV system where you can inform the car that you intend to speed, seems like their lawyers would have a say about that. I guess the system could notice what your previous habits are in regards to the speed limit (just don't tell the lawyers). But wait, maybe dad likes to speed but when mom is driving she goes the speed limit (or vice-versa). Since it doesn't know who will be driving, the EV estimator will also have to be tied into the seat memory system, i.e. who is driving today, fob #1 (law-abiding spouse) or fob #2 (speeder spouse)
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post #24 of 26 (permalink) Old 10-26-2020, 10:12 PM
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Actually, I was responding to obermd's post about how "Volt owners refer to the battery charge information in the Volt as a Guess-o-Meter."


You are speaking of an EV range estimator which is different. I assume that a battery charge information gauge would read the percentage of charge left in the battery. The amount of charge that's put into the battery can be measured and the amount of energy extracted from the battery can be measured. Of course there are variables that need to be taken into consideration such as how efficient the charging of the battery is.



But you are right that the gas gauge is an instrument taking a reading. It's just that it's not reading the quantity of the gas in the tank, it's essentially doing its best at reading the height or level of the surface of the fuel above the bottom of the gas tank. Therefore to use that measurement as a gas gauge is an extrapolation.


The same is true for speedometers. They are not instruments that measure the speed or velocity of the vehicle. Instead, they read the number of revolutions of an axle or possibly a driveshaft. Therefore, they also extrapolate the vehicle's speed from this measurement. If you're stuck in a snow drift and spinning your wheel(s) the speedometer will likely show that the vehicle is moving when it's really not.


My point is that many of the 'gauges' in a vehicle are at least a little bit removed from reality. Without getting into semantics, my statement that a gas gauge is essentially a 'guess' is based upon the fact that it does not actually measure what it purports to measure.
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post #25 of 26 (permalink) Old 10-27-2020, 03:11 PM
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Actually, I was responding to obermd's post about how "Volt owners refer to the battery charge information in the Volt as a Guess-o-Meter."

You are speaking of an EV range estimator which is different. I assume that a battery charge information gauge would read the percentage of charge left in the battery. The amount of charge that's put into the battery can be measured and the amount of energy extracted from the battery can be measured. Of course there are variables that need to be taken into consideration such as how efficient the charging of the battery is.

But you are right that the gas gauge is an instrument taking a reading. It's just that it's not reading the quantity of the gas in the tank, it's essentially doing its best at reading the height or level of the surface of the fuel above the bottom of the gas tank. Therefore to use that measurement as a gas gauge is an extrapolation.

The same is true for speedometers. They are not instruments that measure the speed or velocity of the vehicle. Instead, they read the number of revolutions of an axle or possibly a driveshaft. Therefore, they also extrapolate the vehicle's speed from this measurement. If you're stuck in a snow drift and spinning your wheel(s) the speedometer will likely show that the vehicle is moving when it's really not.

My point is that many of the 'gauges' in a vehicle are at least a little bit removed from reality. Without getting into semantics, my statement that a gas gauge is essentially a 'guess' is based upon the fact that it does not actually measure what it purports to measure.
You are right I completely misread obermd's post and thought they were talking about the EV range estimator because that is what the guess-o-meter moniker is normally used for, rereading their post I realize now that they were in fact referring to battery charge or SOC indicator which apparently some Volt owners also refer to as a guess-o-meter.

Another example of what you are talking about are the instruments used in airplanes, like the altimeter doesn't actually measure altitude, it measures barometric pressure, and then based on the typical change in pressure that occurs with altitude it then makes an estimate of your current altitude. For it to be really precise it requires that you input the adjusted sea level barometric pressure of the area that you are flying over, without that information it does start to get into some guessing. Interestingly airplanes flying at high altitudes all use a standard sea level barometric pressure of 29.92, which even though most of the time that will be wrong, since everyone's altimeter is using the same wrong barometric pressure, then the altitude relationship between airplanes will be accurate, and that's really all that you are concerned about at that point is your relationship to other airplanes, at high altitude the exact distance to the ground is not as important.


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Volt owners refer to the battery charge information in the Volt as a Guess-o-Meter. The reason for this is there is no battery/electrical equivalent to a gas tank's float system, where the float's position on a vertical rod is measured and then converted into gallons left. It really is a guess, albeit a very well calculated guess.
Okay now that I have read your post correctly I understand the comparison with a gas gauge.
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post #26 of 26 (permalink) Old 10-28-2020, 01:47 AM
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You are right I completely misread obermd's post and thought they were talking about the EV range estimator because that is what the guess-o-meter moniker is normally used for, rereading their post I realize now that they were in fact referring to battery charge or SOC indicator which apparently some Volt owners also refer to as a guess-o-meter.

Another example of what you are talking about are the instruments used in airplanes, like the altimeter doesn't actually measure altitude, it measures barometric pressure, and then based on the typical change in pressure that occurs with altitude it then makes an estimate of your current altitude. For it to be really precise it requires that you input the adjusted sea level barometric pressure of the area that you are flying over, without that information it does start to get into some guessing. Interestingly airplanes flying at high altitudes all use a standard sea level barometric pressure of 29.92, which even though most of the time that will be wrong, since everyone's altimeter is using the same wrong barometric pressure, then the altitude relationship between airplanes will be accurate, and that's really all that you are concerned about at that point is your relationship to other airplanes, at high altitude the exact distance to the ground is not as important.



Okay now that I have read your post correctly I understand the comparison with a gas gauge.
Wow, you know a lot about airplanes. I am going to guess that you are a private pilot. I am, myself, a private pilot and that’s the only way I would know that planes that fly above 17,999 feet use the standardized baro pressure of 29.92 to set their altimeters. Another good example is the airspeed indicator which involves a comparison between a pitot and static pressure. And even that has to be adjusted for different altitudes.
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