Cost of ownership long term (those batteries...)

I purchased my Clarity (vs lease) and fully plan to keep it 7-10 years. I don't believe I will have to replace the batteries during this timeframe. It is my understanding that in California, car manufacturers have to provide a 10 year warranty on the EV car batteries so even though I only have an 8 year warranty I'm sure they are designed to last longer. Will there be any range degradation over 10 years? Possibly, but I doubt it will be significant enough for me to have regretted my purchase.

Having said that, I would expect that replacement batteries would be very expensive and likely far more than the value of the vehicle after 8-10 years. Hopefully that won't be an issue for me!

 

I have plans to keep the Clarity for 10 years. I have a history of making our cars last. Our other car is a 2005 4Runner. We kept one Prius for 8 years.

1) I expect the battery to continue to serve even though it will lose some range. We have extra range every day so that shouldn't be a problem. California is 10 years or 150,000 miles on the battery but that applies to failed batteries. Normal deterioration isn't included.

2) Resale value on the Clarity is not likely to be very high so keeping it makes sense to me.

3) Battery advancement, specifically that which will drop charge times to under 15 minutes, will favor BEV rather than PHEV which will further reduce the sale value of the Clarity.

4) I hate to have anything that isn't working so I always fix, or have fixed, things that break. My cars usually look pretty new after many years so I'm happy to keep them.

I think the Clarity is a significantly superior car. It has some things that I wish were a bit better but it's the nicest, smoothest riding, most comfortable, best cornering, car I've ever owned or driven. It's perfect for us as our daily trips are in the 30 mile range, and being retired we come home and charge mid-day. So we drive for weeks without using any gas. Then when we take an out-of-town trip we have long range and quick refill capability. Best of both worlds.

 

We leased our Bolt knowing the battery chemistry and charging rate will be improved in three years, not to mention many more choices in full EV's. I bought the Clarity and plan on keeping it a long time. I think PHEV's must be thought of differently from full EV's, no matter what happens you have the gas engine to get you home. Even if I lose 50% of my battery capacity in 10 years I will, in my opinion, end up having a large Prius Prime (talking about the EV range). ALSO a 50% loss is extremely unlikely, our last full EV lost less than 3% in 3 years. The Clarity has a good thermal management system as did our previous full EV, this makes all the difference. I believe the warranty does cover the battery if it drops below a certain point, 36.6Ah out of 55Ah, that works out to 66%(or a loss of 33%). As far as long trips I expect to keep getting around 50mpg even if the battery drops to 20% of what it has now. We really like our Clarity.

 

I imagine that in 8-10 years, the cost of the same capacity battery should be significantly less than today's battery. What is perhaps more interesting is whether a similar-cost or similar-size battery in 8-10 years could have an increased capacity that would significantly increase the battery-only mileage. That would be the best of all worlds -- driving the Clarity for 8-10 years and then effectively turning it into a BEV by swapping in a future-generation battery. One can dream ...

 

I kept my previous car, a 2006 Civic Hybrid for 12 years. Replaced the battery pack for $2000 after 10.5 years. The car still drove even with the degraded pack, but I fixed it.

Now, the car lives on with a family member, since I wanted something nicer.

I plan on keeping my Clarity a minimum of 10+ Years. But this car is a gateway drug that will probably make me go full BEV the next time around, as I enjoy driving on electric so much.

 

I get over 60 miles of range outside of winter so even if it degrades as much as 50% after 10 years (which is more than expected), I'll still have more range than most current PHEVs when they're new. Plus, it'll still operate fully fine as a HV.

 

I am thinking of selling ours by year 7 and go full BEV. Fast forwarding, there won't be many used decent PHEVs available used and ICE cars will be less in favour. Hondas hold their value well and this will be the only used large Japanese PHEV sedan on the market for model year 2018.

 

If this is any help, I bought my 2012 Prius Plug-in, one of the first of their PHEVs. I kept it until December of last year, so almost 6 years. It was worth $12-15K according to several sites, and I traded it for $12K to buy the Clarity - which was about 1/3 of the initial cost of the Prius. In terms of cost, the Prius PHEV cost more in 2012 than the Clarity in 2018 by several thousand dollars. The Prius PHEV had less than the 1/3 EV range that the Clarity has now. Its motor and engine combined were about 100HP less than Clarity. It's a much nicer car in all ways.

So there will likely be advancements in 4-6 years that may make a Clarity less valuable. However, I believe there will still be somewhat of a market given its EV range. Even if the range declines by 25% in 5 years, it should still have decent range.

It's hard to predict what the world will be like economically in five years. If gas prices continue to climb, there may be more of a market. If things turn the other way and we decide to ignore earth science and burn fossil fuels whenever possible, it may not be much of a sales item. If you are buying a car solely based on its resale value, then this is probably not the car you want. Just too unpredictable.

 

Same question came up when I bought my 2007 Camry Hybrid in 2006. I traded it in for my Clarity last month. 12 years and the battery was never a question.

 

With liquid cooling in the Clarity, the batteries should be robust for a long time, but it may also depend on how aggressive one drives, how deeply it is discharged before recharging, how often it is charged to maximum capacity (limited by the BMS, but that buffer may get depleted over a period of years), and how hot the ambient conditions are over its lifetime. Meaning EV batteries in the north will likely outlast batteries in Arizona on average.

Here is a slide presentation with some interesting details: https://www.nrel.gov/docs/fy14osti/62813.pdf

 

A Tesla with a 100 kWh battery will last more than 6 times as long as a Clarity (17 kWh) if you drive both the same way (in all EV). That's because the depth of discharge (DoD) will always be less with the much bigger battery (for the same usage) and that's one of the factors that determines battery longevity. As Ray B pointed out, the storage temp also affects longevity. The ideal temperature is a bit below room temperature. Higher is the worst and the cooling system does not kick in unless the temp is much higher than room temp so if your car sits well above room temp a lot, that will hurt battery longevity. Those of us up North aren't a lot better off. Letting the battery sit below freezing is also very harmful. That all sounds dire but check out this guy's video on his Outlander PHEV:

He has a long series of videos complaining about how bad his PHEV battery is but his usage is pretty much the worst you can treat a Li ion battery (Storage at very hot temps, small battery, mostly high speed driving, fully charge and fully discharge daily--extreme DoD). Despite all that, he's only lost 22% capacity after over 4 years and 45,000 miles of usage at almost all EV. Because the Clarity is 17 kWh vs the 12 kWh of the Outlander, we can expect much better longevity than that, especially if your conditions are not as extreme. Besides, Honda designs and builds much better cars than Mitsubishi so we have that going for us too.

 

I think that for normal overnight charging it should have a long life, particularly in the moderate temperatures you describe. It is a point of debate and conjecture whether keeping the battery usage in the ~80% - 30% window for maximum life. The BMS already does keep a buffer at either end. Over a period of years this buffer may get depleted, and at that point it would maybe help limit degradation to stay away from the 100% recharge state, but it appears that there is no good way of knowing when that buffer is gone, unless you begin to notice a distinct drop in the estimated range when fully recharged.

I would think that for most users there is no reason to fret about it, and just recharge normally and not worry about it. The Clarity has BMS and a cooling system to maximize life. If there is a desire to 'hypermile' the battery life then some of the strategies can help.

 

Crunching the numbers based on 14.1 kW maximum draw reported from an EVSE and appropriate inefficiency is the car’s charger, you find the BMS is keeping around a 24 to 26% buffer in the SOC. This compares well with reports of other BEVs. We just didn’t know the ratio that it was split between top and bottom.
That is until @AnthonyW started beta testing a Scangauge and graphed out some very interesting results. He’s nicely bolstered the case that the BMS starts off keeping the SOC between about 85 and 20%.
See his post #44 in this thread:

https://www.insideevsforum.com/community/index.php?threads/scangauge-ii-extended-pids-capacity-and-specific-energy.2633/page-3

So I have to agree with @Ray B and several others that the BMS is already doing a good job protecting our batteries and any added effort on our part will yield such a small improvement that it is not really worth it for me.

 

Thanks @KentuckyKen for the mention. In regards to the buffer, we reasoned that since about 14.1ish kWh goes into the car using a Level 2 charger, and using the standard 88% efficiency that suggests about 12.4 makes into the battery. But what if less actually makes it into the battery? We have yet to consider the energy used to cool or heat the battery while charging. Running the cooling system definitely consumes power when it is hot. When it is cold, the battery packs have a thermistor that helps warm the battery before charging, so we are probably using a lot of energy bringing the battery up to temp. Therefore the kWh that go into the battery are probably much less than we think.

 

Even better! Using those assumptions, we are only using at most, 73% of the total 17 kW battery, leaving at the least a 27% buffer. I really appreciated your data collection and analysis that gives us our first insight (that’s for @insightman) into how the total is split between top and bottom. It is encouraging that all the data so far agrees fairly closely with each other and with what has been reported for other vehicle’s batteries.

 

Ray B you are spot on. Not sure if this technical paper "Battery Control Technology of Li-ion Battery System for HEV" has been shared yet but it was written back in 2013 by the engineers at Honda. While it is talks about the lithium battery in the Civic, it is most likely the foundation of the system in our car. This figure shows that the buffer in the battery is reduced over time so that we don't lose any range:


If my theory is correct that there is a 35% buffer, you get an idea of how long Honda thinks the battery will last in the next figure. It also gives you an idea of what is to be gained if you baby your battery.


Lastly, see the SAE paper attached "Integrated Cooling System for Underfloor High Voltage Devices in PHEV". It is not a traditional "cooling system" that you might think of. It is more about heat rejection, thermal resistance and out-of-target temp avoidance. Nonetheless it is designed to extend the battery life 15% and meet the end of life criteria: