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Discussion Starter · #1 ·
When I have charged my Clarity 2018 to the maximum and than go for a short trip say down 2 bars on the charge indicator when I turn the car off. When I start the car again after some time , especially overnight, the charge indicator seems to be several bars lower. Is this real and what is the explanation? When the car is fully charged in the evening it is always fully charged the next morning. This only seems to happen after using only a little of the charge and then letting the car sit. Is the amount of charge being reevaluated over time?
 

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When I have charged my Clarity 2018 to the maximum and than go for a short trip say down 2 bars on the charge indicator when I turn the car off. When I start the car again after some time , especially overnight, the charge indicator seems to be several bars lower. Is this real and what is the explanation? When the car is fully charged in the evening it is always fully charged the next morning. This only seems to happen after using only a little of the charge and then letting the car sit. Is the amount of charge being reevaluated over time?
It’s possible that because of change in temperature or some other variable that the no-load battery voltage changes slightly. Or it could have something to do with the software algorithm that calculates the amount of charge left in the battery. I have noticed slight changes as you have described but they seem to average themselves out over time. Just remember that the charge indicator and the EV range are merely guesses as to the remaining capacity of the battery. Concentrate more on the reality of how many miles you actually get to drive the car before the ICE kicks in.
 

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The Clarity's High Voltage battery trickle charges the 12V battery. Check the 12V battery for a parasitic load.
 

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Discussion Starter · #4 ·
I thought about that but since the indicated level never seems to drop if it starts at 100% I eliminated that. It must be that some algorithm is manipulating the displayed charge level. Yesterday I started with a full charge and drove about 6 miles and stopped to eat. When I stopped the charge indicator had not dropped at all. When I got back in the car 1/2 hour later the charge indicator started off unchanged but after driving about 1 mile it dropped 3 bars. It doesn't really cause any problem but it is curious behavior.
 

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I thought about that but since the indicated level never seems to drop if it starts at 100% I eliminated that. It must be that some algorithm is manipulating the displayed charge level. Yesterday I started with a full charge and drove about 6 miles and stopped to eat. When I stopped the charge indicator had not dropped at all. When I got back in the car 1/2 hour later the charge indicator started off unchanged but after driving about 1 mile it dropped 3 bars. It doesn't really cause any problem but it is curious behavior.
I'm not sure if what you are experiencing is normal or indicates a problem, as I don't really pay that much attention to the bars, mainly because I have to stare at them and count the bars since it only has a marker for 50%, I guess I am too lazy. But also it's not quite as precise as SOC since each bar represents 5% SOC. You can see SOC on the HondaLink app, it's on the first screen on the line that shows the EV range, the percentage you see there is the SOC.

The limitation with the HondaLink app is that it only updates SOC when you turn off the car, not while driving. Whenever the car is turned off it "phones in" to Honda via the cellular network to report the car's location, the battery SOC and the HV miles remaining. This information is usually available in the HondaLink app within a minute of shutting off the car.

To see SOC while driving you can use an inexpensive OBD-II reader and a free phone app. It's fairly easy to set up and very easy to use. And it has other benefits like you can check your battery capacity, which starts out at 55 Ah for a new battery. Most 2018's will be around 50 Ah by now which is a 10% reduction in EV range. The OBD-II reader shows many other things like engine RPM which can be interesting, cabin temperature, and even the number of days remaining before you get maintenance minder messages so that you will have an idea how much longer you have on the various items. And you can have your phone showing SOC while you are driving and it will update real-time without having to touch the phone.

There is really only one combination that works for this, the Vgate iCar Pro OBD-II reader which is around $35, and Car Scanner app. Works for both Apple and Android. In Car Scanner when you select Clarity it will read all of the Clarity specific data. The first time you use Car Scanner, you go to the "All sensors" icon, which gives you a long, long list of the various data, which is okay but it's worth setting up what they call dashboard where you can display just the items that you want to track.
 

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I don't know if this helps you any but that first bar seems to get me a lot more miles than the 2nd bar, and consecutive bars after that. Similar phenomenon with gas, the first bar gets a lot more miles than the rest. I know I'm probably overfilling the gas tank but I think the EV bar meter isn't really accurate in that way...
 

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Discussion Starter · #7 ·
I agree with you on that. Honda probably did that on purpose. Someone earlier stated about another issue that Honda designed the Clarity to behave like a ICE car to make users feel comfortable and every ICE car I have ever owned has gone several miles on a full tank of gas before the gas gauge needle ever moved.
 

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I have been rereading this thread a couple of times because sometimes I just speed through and miss something. I think @ClarityDave hit on an idea of temperature dropping overnight. It could be a simple V meter and drop in Voltage (is this temperature dependent?) overnight causes the level to drop. The next question would logically be why doesn't it show with the first bar? I would guess because that first bar is actually worth more miles than each of the remaining bars it would take a significantly larger temperature, and hence V drop, to show up.

Maybe someone familiar with the Lithium chemistry used and the voltage curve of such would be able to shed some light on what is going on?
 

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The mileage and charge are not amazingly stable after a restart: There's a Costco across from my work (where I charge). If I pull into the Costco lot with less than 5 miles of range, when I restart after shopping the guess-o-meter reads 0 and i need to use the gas engine to get the <1 mile to the chargers. I'd guess that it's voltage check (to estimate charge) allows for some slack while running, but does a new reading when I restart and determines that it wants power now.

Costco has EV parking--wish they'd install a few slow chargers.
 

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@2002 or others, is there a way to get Car Scanner (when paired with the Vgate OBD2 reader) to display the voltage of the 12v battery in the Clarity? I looked under All Sensors and saw the various HV battery voltage and an OBD voltage, but couldn't find the voltage of the 12v battery. Any guidance will be greatly appreciated.
 

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@2002 or others, is there a way to get Car Scanner (when paired with the Vgate OBD2 reader) to display the voltage of the 12v battery in the Clarity? I looked under All Sensors and saw the various HV battery voltage and an OBD voltage, but couldn't find the voltage of the 12v battery. Any guidance will be greatly appreciated.
Reading voltage of the 12V PbA Auxiliary battery really doesn't tell a whole lot about its health, unless it's under load.
 

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Reading voltage of the 12V PbA Auxiliary battery really doesn't tell a whole lot about its health, unless it's under load.
Does OBD2 have any indicators for the state of health of the 12v battery? My wife and I are planning on doing multi-day road trips to remote national parks. I just ordered a lithium jump starter on Amazon, but thought that having a measure of the 12v battery's health might be good information to have.
 

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@2002 or others, is there a way to get Car Scanner (when paired with the Vgate OBD2 reader) to display the voltage of the 12v battery in the Clarity? I looked under All Sensors and saw the various HV battery voltage and an OBD voltage, but couldn't find the voltage of the 12v battery. Any guidance will be greatly appreciated.
Hi! The Pro version of Honda (rhymes with Jack but starts with an H) allows you to view the battery voltage on the infotainment screen in real-time (and a bunch of other features as well, like pressing OK at start of distraction screen, et cetera). I have had it installed for the last few weeks, and it’s been amazing so far.
 

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Does OBD2 have any indicators for the state of health of the 12v battery? My wife and I are planning on doing multi-day road trips to remote national parks. I just ordered a lithium jump starter on Amazon, but thought that having a measure of the 12v battery's health might be good information to have.
There is a reading for OBD-2 voltage, which probably doesn't come from the car's data output but is simply a measurement by the device of the voltage of the circuit that it is on. I would think that this is probably reasonably accurate.
 

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There are also devices that plug into the "cigarette lighter" socket that displays the 12V system voltage, but again, it's not telling you a whole lot, because it's got charging circuits pushing on it, and it's not necessarily under load.

The aftermarket TPMS sensor display I've got shows the 12V system voltage.
 

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Ok. So to get a better sense of the 12v battery health I should measure three voltage under no load and then again under load and look at the difference in the voltage. Maybe do this when the battery is new and healthy, and then do it again later as the battery ages.
 
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