Hillbilly battery check?

Some owners have reported 13-14kWh’s for a full charge. 12kWh’s could indicate a bit of degradation.

 

It is unlikely that the charging system is 100% efficient. Perhaps 90%. Consuming 13kWh’s might yield 12kWh’s of stored energy.

With the refined measuring features of the Musquirt 2000 you’ll never know if it was 12.00 or 12.49.

 

@craze1cars - Good to hear from you !

I keep a very close watch on charge consumption... Over my 3 years of ownership, I have now charged the Clarity 547 times. Not all of these are 'full' charges, but many are. Here is a graph that includes every charge. Your eyeball can visualize the trend over time for the 'full' charges. These numbers are reported by the EVSE so they represent raw power input to the vehicle. In my case, a full charge was initially running around 14.4 kWh and it has tapered off such that currently a full charge is more like 13 kWh (about a 10% drop):


If you are interested in the actual battery capacity as Honda would see it, I would strongly encourage you to read it out yourself. All you need is a ~$30 OBD2 adapter. There are two main ways to do this - either with a smart phone, or with your PC. Here are specifics of these two techniques:

1. Smart phone - This thread has become very cluttered, but everything you need is there. I should create a more concise version, but haven't bothered. The clutter makes it seem harder than it really is:
https://www.insideevsforum.com/community/index.php?threads/budget-battery-capacity-readout.10531/

2. From your PC - Same adapter is used, but you can read the data with your PC and create a nicely formatted report:
https://www.insideevsforum.com/community/index.php?threads/pc-based-electric-powertrain-report-battery-capacity.12220/

Finally, many of us Clarity Owners have been gathering data and looking at trends for our vehicles. We utilize a shared spreadsheet to collect and plot results. If you know your measurement, you can easily see how your Clarity stacks up. You can look at the data here:

https://docs.google.com/spreadsheets/d/1LHtqVuPzHUDXmX1jiHOQIpT_YiGp9N-vnBOiSz96C2I/edit#gid=1710145002

I think the best graph is this one:
https://docs.google.com/spreadsheets/d/1LHtqVuPzHUDXmX1jiHOQIpT_YiGp9N-vnBOiSz96C2I/edit#gid=1735681880

 

Yes. The precise value varies because the SOC is around 10% when you reach 0 EV range.
It will be plus or minus a few percent depending on how you were driving after reaching 0 range.

I agree that 12-13 kWh of input power is in the 'normal' range for a 3 year old Clarity.

 

For clarification, is battery wear a function of age or mileage? Your response above implies that you would expect the same amount of battery degradation in a three year old Clarity with 15k miles on it as one with 45k miles. It that the case?

 

@BrianRC -
I did not mean to imply that I know the answer to that sort of question... To me, that is the purpose of collectively gathering data. You can slice the data in different ways to a degree, and possibly come up with some theories.

My only point is that most of the Clarities are from 2018. They are 3 years old, but there is a range of miles, mix of EV miles, and driving / charging conditions. When I cited a degradation for a 3 year old vehicle, I was just looking at the spread of dots across a wide range of conditions.

I would encourage you to stare at the data and help look for trends... My instinct is that vehicles with more charge / discharge cycles (particulary deeper ones) may suffer more degradation. The miles may be less important - for instance, a 15K mile vehicle that is driven exclusively in EV mode may have more degradation than a 45K vehicle driven mostly in HV. Simplistically, 15K miles in EV with 50 miles per charge takes ~ 300 full charges. I have 27K miles, and have charged 550 times. I estimate that my mix is approximately 75% EV.

We have a handfull of owners who show battery capacities that are nearly factory perfect (with substantial miles). This remains a mystery... Something about their driving / charging habits is preserving battery life exceptionally well (or the reading is off in some way).

The Clarity has been an excellent vehicle for us (absolutely trouble-free), and I continue to enjoy trying to learn about how it works.

 

Battery degradation is a function of multiple factors. A one year old battery could have more degradation than a 5 year old battery. The variables are nearly limitless.

Time and mileage are both factors. But how many miles were in EV?

 

I forget that everybody doesn't drive like I do which is 95%+ in EV mode, and so far with COVID I have only put about 5,000 miles my PHEV in the first year. I also have the Autel tool to measure battery capacity and I am probably due to add another data point to MrFixit's database. I rarely use more than half a tank per day and I always plug it in at night to top it off. So we'll see how much battery degredation I've incurred in this first year next time I check.

I also totally agree that the Clarity (this is my second) has been an excellent, trouble free vehicle, and I also continue to enjoy trying to learn about how it works.

 

After a cup or two of Joe this morning, it dawned on me that a reading of 12kWh’s from a device that only displays whole numbers, could actually be anything from 11.51 to 12.49. At the extreme, there’s essentially 1kWh of slop. 1KWh represents 7% of the “useable” 14kWh’s.

If your battery is only storing 11.5-12.5kWh’s of energy, it has degraded about 10-18%. So, you might see 45-50Ah’s. But, as you’ve said, who really cares until you near the end of the warranty period, which is 10 years/150,000 miles for ours, or if range suddenly declines dramatically.

 

As a contribution to the discussion about 'measuring' the input energy from charging time, I had a thought...

If your EVSE reports the total energy, that is nice, but if it is very coarse (like the reported Musquirt unit), then perhaps it is better to calculate the input energy from the charging time (as illustrated by @craze1cars above).

Energy is voltage * current * time. At a Level 2 charge rate, the Clarity uses 7.2 kW (240V @ 30A). If you simply multiply the charge time (in hours) times 7.2 kW, you can get a good estimate of the killowatt-hours, BUT there is one small caviat. The Clarity tapers the charge at the end, so there is a short time at the end of a charge cycle where the rate drops 'slowly' to zero. I have always attributed this slow drop-off to cell balancing, but this is speculation on my part.

My EVSE provdes both a charging time and a measure of kWh (with fine resolution). Using my last year of data, I could plot the kWh both ways (measured, and calculated from charge time). Here is the result:



There is an obvious bias where the actual energy is noticably lower than what is calculated from the charging time. This could be due to the tapered charge during the final minutes, and if you throw in a correction by shortning the time by 5 minutes, it looks better:



It is interesting that lots of the points fit the calculated curve very well, but there are also numerous points that don't. There may have been a few (very few) points where I terminated the charge early without allowing the tapering. This would yield a point higher than the curve. The ones below the curve could have required an extended tapering / balancing period?

My conclusion is that the best way to estimate input energy from charge time (Level 2) is to subtract 5 minutes (0.083 hours) from the charge time and multiply this by 7.2 ie: Energy (kWh) = 7.2 * (Charge_time (hrs) - 0.083). I would like to better understand the points that fall short, but that will require significantly more effort.

 

This is much less data intensive than you detailed forum members who I greatly appreciate. My Clarity was purchased August 2018 new and these reading are from my charging station (Juicebox) months 4-6 of ownership a charge from empty (two bars) averaged 13.65 kWh. In 2021 with about 41,000 miles the charge from empty is averaging 12.58. I'd have to say I my EV range seems to have suffered more than that but there are so many more variables involved with that.

It seems like this supports the others findings.

 

Here's another fly in the ointment. My EVSE also shows the service voltage that is being provided by our utility company. It is only very rarely 240V. It varies from around 236V (the most frequent) to as high as 242V. Maybe not a big factor in the equation, but it would have some effect on trying to rely on charge time to calculate total energy.

 

I beleive I have observed that the Clarity will draw a constant 7.2 kW even as the voltage varies slightly (ie: if the voltage goes up to 242, the current will drop to 29.75 amps to maintain the 7.2 kW... If the voltage drops to 236, it would draw 30.5 amps). I am not 100% certain of this, but watch your EVSE and see if you can corroborate it...

In any event, the tolerance on the line voltage is very good (your range 236 to 242 only represents -2% to +1% which is pretty darned good and inconsequential to the intention here which is a rough (Hillbilly?) evaluation of battery capacity.

 

Since I charge during the wee small hours, that's not likely to happen.

 

Set your alarm for 2:00 AM and you can research this question !!!
I'm with you though - not likely to happen !