Least Battery Degradation Possible

Crystal ball has been in the shop for decades now... Depends on whether you believe what some say on the internet about batteries in general, or whether you believe what Honda advises owners to do for the Clarity. The Honda owners manual explicitly states that in order to achieve maximum battery life we should be charging to full every day. I forget the exact wording...but something is the sort.

Let us know in 10 years how it works out.

 

I think it is important to acknowledge the 2nd small subset of owners here who have mentioned an alternate goal at times: Maximize the life of the entire car, not just the battery. To that subset it means it is best to stress the battery as much as possible during ownership, with the goal of having it be capacity-damaged enough that Honda installs a free replacement battery under warranty at the age of 7 years, 11 months.

This indeed would maximize the life of the car, not to mention maximizing resale value, by getting a shiny new Honda battery for free, after their first 8 years of ownership.

This choice of battery management, just like yours, and likely Honda's recommended treatment, all require a functional crystal ball in order to know whether or not it makes sense to attempt. We will all roll the dice.

 

craze1cars

There are several threads to post-up data on battery performance etc. I am sure we all would love to see data off Clarity's with different charging regime's posted. Data is one method to construct potential battery degradation curves to helps folks.

I do not view this as a "you're right - I'm wrong" issue. I view it as an opportunity to learn and to see how things play out over time. Time is the great equalizer.

Care to share?

Look forward to your thoughts and thanks!

 

I’ve seen the threads. Don’t participate cuz I just am not that interested in the results or the hassle of tracking things. I’m less a Clarity enthusiast than some here. I have read a few of the threads and see lotsa speculation of how to measure battery health and some tracking, which is all fine, but I see almost zero Honda battery capacity tests on higher mileage cars, which are the only test results which interest me.

Plus I don’t usually drive the car...it’s wife’s. She won’t want to play along with complicating her driving so I’m not gonna push it. It’s just a car to us and it has about 30K miles now. She just unplugs it and drives it, and when pulled into garage she plugs it back in. Occasionally she forgets to plug in and then uses gas for next trip. Sometimes battery range is exceeded, sometimes it’s not. So I have no idea our percentage of battery vs HV, and I’ve never tracked electricity or gas use, and have a dumb Mustart charger that tells me little data about the last charge, and saves no data.

With all that, I feel even if I attempted tracking it, my data would be of little value. So if I see reduction in range I’ll take it to Honda and have it tested, and will report results. But regardless of performance for sure when 7 years and 6ish months comes around, I will take it in to Honda for a battery test before warranty runs out..frankly hoping it is below their threshold. Save those two instances in the future, since my bumper to bumper is almost expired now and I do all mechanical repairs on cars myself, it's likely my car will never see a dealership service dept to give me opportunities for proper battery tests to be done.

 

There is likely very little the consumer can do to significantly impact battery longevity - most of that burden is shouldered by the design and implementation of the BMS. Those that obsess about charge levels and try to further limit one or more ends of the battery charge/discharge parameters may see a slight improvement in longevity. But many generations of LEAF drivers (with no thermal management of the battery) don't find a direct correlation in degradation between those that baby the batteries and those that don't. Environmental and other conditions beyond the owners control are the primary factors driving the amount of degradation. The owner/consumer might move the needle a little, but probably not worth doing anything other than plugging/unplugging as convenient and letting the EV do what it was designed to do.

 

First the smart aleck remarks.

If you’re home all day, how are you driving 5-6 miles?

Not using the batteries at all would probably achieve the least battery degradation possible.

I know, you’re running essential errands and we didn’t buy the the car to sit in the garage so we could give it to our grandchildren with unused batteries.

What you’re doing, may reduce battery degradation, or it may not. There is plenty of information available on loss of capacity over time, given various charge cycles. The wheel has been invented.

One example I’ve seen that bodes well for battery longevity is very close to what I do when commuting. I charge fully with a L1 charger each night, which is really 90%. The drive to work, which takes place shortly after full charge is achieved, uses ~50% of EV range. Now the cars sits with the batteries at 50%. The drive home depletes the batteries, more or less, which is really ~15%. Then the slow charging begins again.

The average SOC over the 24 hour period is ~50%. Ideal, isn’t it?

You could work the 40-60% charge routine in an attempt to increase battery life. It is only my opinion that you are wasting your time. With a 5-6 mile drive, SOC could be kept anywhere from 4-20 bars.

If I had your current driving patterns, I’d charge fully prior to the first trip and return home with batteries at ~80%. Then do the next half dozen trips, which may take 2-3 weeks, until range got down to 5-10 miles and charge again prior to the next trip.

 

In truth, the warnings about only charging a 70+ kW battery to 90% are almost exclusively about DC charging, which REALLY stresses a battery. "Trickle charging" at L1 and L2 is almost like a gentle massage. Clarity won't allow you to fully charge its 17 kW battery nor will it allow you to fully discharge the battery as it maintains a "cushion" on both the top and the bottom. I don't recall that actual number of kW we get to use but someone will surely provide that information.

 

First, +1 on everything you said.
Second, from the start of the forum, the most anyone has reported is that a full charge from EV range 0, or 2 bars which is usually 10% (sometimes a little less) on the HL app, is about 14.4 kWh. That’s the power from the EVSE and does not take into account the inevitable loss in the onboard charger/converter. Information from several sources and posts lead me to consider the onboard charger/converter efficiency to be about 92% efficient with about 8% lost to the Laws of Thermodynamics.

So 14.4 to 14.5 x .92 = ~13.3 kW actually going into the battery packs. Then 13.3 / 17 kWh capacity of battery = ~78%. So there is at least a 22% buffer built in by the BMS and in under normal circumstances, you will never be allowed to completely charge and drain the battery from 100% to 0% absolute, which would rather quickly degrade a Li-ion battery. That’s why many have to replace their phone batteries in much less time than Honda’s 10 yr warranty.

But we don’t know for certain how the buffer is split between top and bottom. The members of the Clarity Brain Trust (and you know who you are) that have measured voltages and other parameters can weigh in on this since this is as far as an old broken down molecular biologist can go.

I have a gut feeling or hunch that being overly concerned with babying the battery will gain only a small benefit since the BMS and cooling system seem to be robust and well designed. But only time will tell. And until @craze1cars finds his crystal ball, we won’t know exactly to treat the battery so that it fails at exactly 7 yrs, 11 months, and 29 days (or 9 yrs... for Cali.)

So where does that leave us. For me, I try to be kind to my battery since I keep cars along time but I only do so when it’s easily done and I don’t wast time on it.
For example, I garage the car to prevent extreme temperature swings to the battery. I use scheduled charging to charge 2 hours before I usually leave to reduce the time the battery sits at 100% allowable charge instead of having it charge every afternoon when I come home and plug in. If the software would allow 90% charging, I’d do that and take a 5 mile hit on range since it would be easy to do and I seldom drive more than 40 miles in one day. But since it doesn’t, there’s no way I’m taking the time to calculate the time and either reset the timer or keeping track of when to unplug. Ain’t gonna happen. However, I will skip o/n charging if I’m above 50% and know I have little or no driving for the next day. Since that only happens about once a week or so, I don’t worry about the cells not being balanced that day.
The other thing I can easily do is reduce the depth of discharge (which is why I think Honda says plug in before very drive) by not letting the SOC go below 30-40% which is easy to do with my low distance local commuting.
And I don’t usually charge right after returning home (unless I have to) to keep from charging a potentially hot battery. And in 2+ years, I’ve only heard what I assume to be the battery cooling system one single time.
So in summary I try to be kind to my battery but don’t take the time and effort to baby it.

Of course, YMMV as always. And @Cash Traylor and I must have a common ancestor since Murphy seems to be our constant copilot, which probably means my battery will hit 36.6 Ah one day after 8 years.
Oh, and I’m not worried about jigaWatts since didn’t the last Delorean in the movie have a fusion device that ran on banana peels?

 

You guys make me feel like a monster. I drive 33 (17mi highway @ 75 mph, 78mph if I don't feel like hypermiling) miles each way 5 days a week, charge on both ends. I don't even think about what it will do to my battery.

115 degree days are fast approaching too

 

I get in, drive it, get home, charge it. It will probably outlive me so I'm not going to worry about it.

 

Agreed, the only reason to worry about this is if you have nothing else to do, and right now there is a lot to NOT do. My goal is to abuse my battery in the hope of getting a new one before the warranty expires. After which I will baby it... If I get that backwards then I have really screwed up! And yes, Murphy will be laughing at me the entire time...

If you are bored, as I have been stuck on the ground in one place, feel free to test or play with this tool in addition or Ray's on this thread. Can be entertaining for about 5 minutes, then I go sit in my car and listen to music that my kids and wife don't like - in my garage. At least I can have the car on and not worry about CO!!!

https://www.insideevsforum.com/community/index.php?threads/battery-degradation-behavior.8620/page-2#post-97771

Cheers and best wishes,

Cash

 

For the most part, you can use the battery for certain miles before it degrades to certain level. If you hold EV miles in the beginning, you might end up using them toward the end or not. It is not possible to drive more EV miles by holding back now. So they only justification for not using EV range is there is some drivability issue that you are trying to avoid (like a big upgrade).

 

Crazr1cars
Kool. Works for me. Couldn't agree more it's just a car. The Clarity is a 5 to 6 year placeholder for me as well.

I believe everyone would love to know the real world data at 100k. That'd be awesome.

The unfortunate reality is...in order to develop real world data curve(s) that prove useful to the everyday driver requires data collection through out the life cycle of the product. Early on provides a base for down the road as it were. At least IMHO.

As the saying goes today....it's all good.

Stay safe n have a great day.

 

These are valid points on when and how to use EV range on a particular trip, especially when that trip exceeds EV range. This, however, is just utilizing available battery capacity on a day to day basis.

The discussion thus far, has been about concerns of long term battery degradation and how different driving and charging habits might effect battery capacity over time.