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[BrianTRice@gmail.com]

This is a remarkably well-presented study of several thousand EVs over time, with some charts.


Here are their summary recommendations, which align with what I've been hearing over the years from various manufacturers and engineers:

• Avoid keeping your car sitting with a full or empty charge. Ideally, keep your SOC between 20-80% particularly when leaving it for longer periods, and only charge it fully for long distance trips.
• Minimize fast charging (DCFC). Some high-use duty cycles will need a faster charge, but if your vehicle sits overnight, level 2 should be sufficient for the majority of your charging needs.
• Climate is out of an operator’s control, but do what you can to avoid extreme hot temperatures, such as choosing shade when parked on hot days.
• High-use is not a concern, so fleets shouldn’t hesitate to put them to work. An EV isn’t useful sitting idle in the fleet yard, and putting on more miles per vehicle is overall a better fleet management practice.

Links:

• Article: https://cleantechnica.com/2019/12/16/new-data-shows-heat-fast-charging-responsible-for-more-battery-degradation-than-age-or-mileage/
• Original study write-up: https://www.geotab.com/blog/ev-battery-health/
• Charting tool for various vehicle model-years: https://storage.googleapis.com/geotab-sandbox/ev-battery-degradation/index.html

[shayan]

I wonder how the minimize using DCFC applies to Tesla's that frequently charge through the supercharger.
Another point is where its stated that the nominal capacity being much lower than the actual capacity is a good thing. This certainly makes sense without having to add too much stress to the battery especially when its passively cooled. Adding some sort of an active cooling to the pack can certainly make a big difference to the Zeros.

I wonder what a low hanging fruit can be for Zero, in terms of having some form of active cooling to the pack.

-Shayan

[Richard230]

I will be a good test case for leaving the battery pack fully charged all of the time.  So far I have owned my 2018 Zero for just over two years and there has been no apparent degradation of my pack since my bike was new.   

Those recommendations might be for owners of EVs who want to keep their vehicles for many years. That is not me. 

[Crissa]

The problems with these recommendations is that every vehicle has a different battery configuration.

Some are passive or air cooled, so fast charging is a problem.
Some have more or less 'reserve' capacity or different nominal capacity and hence are bothered by running to 0 or holding at 100.

And some have more use-it-or-lose it chemistry, like the pre-2014 Zero batteries.

Still, they're fairly common sense suggestions.

-Crissa

[valnar]

I bought my new Zero FXS 2020 a month ago and it sits in my garage here in Ohio for the Winter.  Because of that same weather, I will end up riding it rather infrequently compared to those in California, but still as much as I can.  I will probably not get my money's worth from the battery, and I knew that when I bought it.  I'm okay with that.

My biggest fear is degradation as it sits.  Anything I can do to minimize battery aging is paramount.  Right now it's at about 59% SoC.  When I do ride it, I'll do my best to keep it between 20-80% unless I need that extra push.  High-speed charging will never be an issue since the onboard charger charges at .1C compared to the capacity.

[enaef]

"GeoTab found that the the two biggest factors affecting the life of EV batteries are battery cooling and frequent high power DC charging. Age and number of miles driven are far less important to how long a battery lasts."

That corresponds well with the 5 year warranty with unlimitied miles Zero gives for their ZF14.4 Power Packs, while Zero warns from losing the warranty if one doesn't adhere to the Zero-charging-recommendtations which pretty much reflect the recommendations discussed in this thread.

[Richard230]

I still would like to hear from someone who has experienced noticeable battery degradation of their Zero battery pack - that wasn't the result of the stock on-board charger going south or that wasn't caused by actual battery failure. 

[Crissa]

And for a bike that sat around:  I took possession of my bike and at ~600 miles and 5 years old ....with no real detectable degradation.

Basically there doesn't seem to be any real worry about the batteries from 2014 and on.

-Crissa

[Doug S]

Basically there doesn't seem to be any real worry about the batteries from 2014 and on.

I couldn't agree more. People get all worked up over maximizing their battery life, but there just isn't any need to. I'm just short of 50,000 miles on my 2014 SR, I keep it plugged in all the time when it's at home, and I don't have the slightest sign of battery degradation. It's a total non-issue.

[Richard230]

Basically there doesn't seem to be any real worry about the batteries from 2014 and on.

I couldn't agree more. People get all worked up over maximizing their battery life, but there just isn't any need to. I'm just short of 50,000 miles on my 2014 SR, I keep it plugged in all the time when it's at home, and I don't have the slightest sign of battery degradation. It's a total non-issue.

I agree. But I bet it was some kind of an issue in the Farsis lab.     Personally, I think Zero could get away with a 10-year warranty on their battery packs.   

[Richard230]

I just visited my daughter today and checked how her 2014 Zero S with PT was doing after having the new factory charger installed for the past 6 months.  The bike's charger had been plugged in for the past day.  Her battery pack is doing better than mine. It was showing 117 volts @ 100% SOC and battery balancing was alternating between 1 and 2 mV.  My 2018 S typically shows 116 V @ 100% SOC, with balancing alternating between 3 and 4 mV when fully charged. Her bike has 16,300 miles on the clock. My bike only has 6,500 miles.

[valnar]

Just because people haven't noticed battery degradation in ~ 5 years doesn't mean it isn't happening.  In 10 years you should.

Farasis did not change the laws of lithium technology.  Age is not a friend.
Let's not forget this post: https://electricmotorcycleforum.com/boards/index.php?topic=5314.0

[Crissa]

Someone was asking about battery degradation within five years.  We have an answer.

Yes, lithium batteries work until they fall off a cliff.  At some point in the next five years, we'll see that begin to happen.  But the point was, one can get a good number of miles out of the current packs to be price-competitive with the ongoing maintenance cost of an ICE vehicle.

-Crissa

[talon]

I am told by a leading battery expert with in-depth knowledge of Zero's that my battery is showing signs of increasing impedance. Apparently impedance can increase in (at least) 2 ways? I bought a never-before-titled 2016 SR in 2018 (so batt warranty until 2023). While I have full range, my battery heats more than expected. So while the impedance is not affecting my capacity, it is said to be affecting temperature. It takes very short bouts of spirited riding or charging at <=0.6C [for less than 1.4 hours] to overheat my battery past 124F (opening contactor) on a cool ambient day with shade and wind. I'm told this is likely grounds for replacement but I think I will reevaluate this Summer to see how it does on a few 200-600 mile trips. I only have 10,000 miles. Even the stock charger could overheat my battery occasionally, but perhaps for different primary causes.

I almost always store at 40-60% and purchased the bike with extremely low miles on it.

[valnar]

I'm told this is likely grounds for replacement but I think I will reevaluate this Summer

Does that condition qualify for a warranty replacement?  If so, why wouldn't you just get it replaced?