Lifetime Battery Cycles?

[Geor99]

I'm just curious if anyone knows the # of estimated battery cycles in the Clarity before severe reduction in the ev miles occurs.

I was thinking that since I charge twice per day, 6 days per week, from dead to 100% that's 2×6x52=624 per year.

I would think 10 years or 6000+ cycles is probably out of the question.

Anyone know what the Honda estimates are?

 

[Geor99]

I'm just curious if anyone knows the # of estimated battery cycles in the Clarity before severe reduction in the ev miles occurs.

I was thinking that since I charge twice per day, 6 days per week, from dead to 100% that's 2×6x52=624 per year.

I would think 10 years or 6000+ cycles is probably out of the question.

Anyone know what the Honda estimates are?

I commute 37 miles and have free work charging, so I completely charge 2x per way and twice 0n the weekends.

 

[jdonalds]

In CA batteries must be warrantied for 10 years or 150,000 miles.

My son has our 2008 Prius with 190k miles on it but the battery (and hybrid mileage) seems to be holding up well. By the way they are just now having to replace the original brakes.

 

[Emanuel Green]

Honda says they will replace the battery under warranty if its capacity drops below 36.6 Ah. That's 66% of the original capacity. The warranty is good for 8 years / 100,000 miles (10 years/150,000 miles in California). So Honda is expecting that most of the batteries will experience less than 33% degradation in 8 years.

It's still too early to tell how well they will hold up long-term in the real world, though.

 

[Ray B]

I'm just curious if anyone knows the # of estimated battery cycles in the Clarity before severe reduction in the ev miles occurs.

I was thinking that since I charge twice per day, 6 days per week, from dead to 100% that's 2×6x52=624 per year.

I would think 10 years or 6000+ cycles is probably out of the question.

Anyone know what the Honda estimates are?

There is very little published specifically on the Clarity PHEV's battery, and only some general information on similar batteries in other Hondas. Probably the paper that comes the closest to the topic you are interested in is this one - https://www.hondarandd.jp/point.php?pid=1257&lang=en - on the battery from the 2013 Honda Fit Hybrid (which uses the EH5 battery rather than our EHW5 - similar but not the same).

In several of their other papers it is clear that lifetime is affected most by high temperatures. When in operation, the EV battery cooling system manages to pull away the heat very effectively. But it is probably bad to leave a parked car with a fully charged battery routinely sitting in the heat for a long time. If it has no alternative on hot days, it is better for the battery to keep it closer to 50% SoC when possible, to maximize capacity retention for long life.

 

[Richard Kelly]

From several articles that I have read, in addition to heat, the way the battery is charged has a lot to do with how many cycles it can last. The less deeply it is discharged and the less it is fully charged, the higher the number of cycles it is expected to last, this is why Honda does not allow the battery to drop below 2 bars and why the battery is only partially charged (14kW of the actual 17 kW capacity of the battery I think I read). Please correct these numbers if you have different information. I will try to dig up a link the the article that had the chart comparing lifecycle to % charge/discharge.

 

[4sallypat]

Reminds me of the nickel cadmium (NiCd) batteries of the yesteryear where they developed "memory faults"...

Not to say this Honda battery pack is the same chemistry, but don't you think this high tech battery would perform more like a nickel metal hydride (NiMH) battery that does not care about how deep the battery is discharged or recharged ???

 

[Ray B]

From several articles that I have read, in addition to heat, the way the battery is charged has a lot to do with how many cycles it can last. The less deeply it is discharged and the less it is fully charged, the higher the number of cycles it is expected to last, this is why Honda does not allow the battery to drop below 2 bars and why the battery is only partially charged (14kW of the actual 17 kW capacity of the battery I think I read). Please correct these numbers if you have different information. I will try to dig up a link the the article that had the chart comparing lifecycle to % charge/discharge.

Yes, they want to avoid very high or very low SoC as that accelerates battery degradation, and so they built in a buffer system as you mentioned. This paper - https://www.hondarandd.jp/point.php?pid=104&lang=en - shows how the 100% SoC ('real' SoC, not our 100% SoC which is after the buffer is in place) leads to faster degradation of the battery life. After that they show how the buffer manages during the performance lifetime to hold a certain level of capacity (range), while extending the life of the EV battery.

 

[Ray B]

Another really good paper from Honda on EV battery lifetime, based on the usage data from the Honda Fit EV.

https://www.hondarandd.jp/point.php?pid=1203&lang=en

There is a reassuring graph of capacity retention forecasting that doesn't move much off of 100% after 8 years. Probably optimistic!