Daily topping up the battery bad?

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vulgaris_magistralis
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Post by vulgaris_magistralis »

The first time I wanted to take a detour and realized I don't have enough battery, the range anxiety kicked in me. My commute eats up around 30-35% of the battery so practically I can do a round trip twice without a problem. However, I'm finding myself topping up the battery every day from 70% to 100% so I have a piece of mind if I need the range.

I love my car and want to drive it in more years to come. I did a quick research on the effects of battery health but couldn't come to a conclusive answer. Some say up to 80% is okay, the others say it doesn't have much effect. Since our E is quite unique, does anyobody know the definitive answer?

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londiniumperson
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Post by londiniumperson »

No
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EEEE
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Post by EEEE »

Even if there is no definitive answer, just do the 'go for broke' method.

If your habbits do reduce the battery capacity over time, the sooner you can get a new one from honda under warranty.

Generally, the 80% rule applies to raw cells only, not a massively combined pack with unknown management fiddling the numbers. We all know that 0% isn't really 0% , so 100% probably isn't 100% either.

I top mine up nearly every day from 70% to 100%. The car ceases to be a car if you start to worry about all of these details. Its bad enough planning a long journey where to charge without any of the above crap weighing on your mind as well on the daily.

All cars eventually die and fail - enjoy them in the moment...
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vulgaris_magistralis
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Post by vulgaris_magistralis »

The car ceases to be a car if you start to worry about all of these details.
Exactly how I'm feeling about this too. Thanks for the reply.
Rob83
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Post by Rob83 »

I've been wondering this a little bit decided to not worry too much about it. My old Leaf didn't lose a health bar in the time I had it.

I'll charge to max at home but if I'm at a public charger I do tend to stop at 80-90% purely because that last 10-20% takes longer to charge and it isn't worth waiting around. So it's more of a time consideration, not a battery health thing.

I think repeated rapid charges are more harmful to battery health than regularly home charging to 100% but even then I'm just going off what people have said online so I'll happily stand corrected.
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hondaeboy
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Post by hondaeboy »

vulgaris_magistralis wrote: Thu Apr 13, 2023 8:23 pm I love my car and want to drive it in more years to come. I did a quick research on the effects of battery health but couldn't come to a conclusive answer. Some say up to 80% is okay, the others say it doesn't have much effect. Since our E is quite unique, does anyobody know the definitive answer?
Yes. I came across some research a few years ago, and it did confirm that charging it from 0% to 100% constantly would leave you with a battery life of only 1/12th of the lifespan compared to charging it from 20% to 70% all the time. The annoying thing with the current batteries is that charging them full is not good, but also draining them to depletion isn't good either. Theoretically, it's best to keep the battery at 50% at all times. :D But that's just not very practical.

https://pushevs.com/2018/04/27/battery- ... s-partial/

Translating the above research for the Honda e battery, this would give you the following table:

100% to 0%: 500 cycles x 28,5 kWh = 14.250 kWh =~ 100.000 km til EOL
90% to 10%: 1500 cycles x 28,5 kWh = 42.750 kWh =~ 300.000 km til EOL
80% to 20%: 3500 cycles x 28,5 kWh = 99.750 kWh =~ 700.000 km til EOL
70% to 20%: 6000 cycles x 28,5 kWh = 171.000 kWh =~ 1.200.000 km til EOL

But it also seems the Honda e battery has about 20% of reserved capacity (28,5 of 35,5 kWh can be used). This means that you probably can never charge beyond 90% (even if the car says 100%). And when the car says 0%, there's still some 10% energy left in it. So even charging it from 0% to 100% will still give you some 300k km's until the battery is EOL (end-of-life, meaning 70% capacity). So, if you go YOLO on the battery, there's no way you can get it replaced under warranty. However, you will end up with a fucked up battery way quicker. That also seems a bit pointless.
Last edited by hondaeboy on Sat Apr 15, 2023 7:06 am, edited 1 time in total.
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ZoeDave
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Post by ZoeDave »

Regretfully, it seems that only Honda are the ones that might know the answer to your question for sure. But from what I have seen, EV batteries are governed with a great deal more care than those in phones, and even then phone batteries do better when kept closer to 100% than empty, so if I had to guess the greatest stress you are doing to the car might be the extra wear on the type-2 plug.

What I haven't seen is anyone confidently claiming where the (likely over-conservative) safety margin on the e lies above and below the usable range. From some reports, it seems like a decent amount is below 0%, and so it's not impossible that 100% could be a true 100%. I definitely get the impression that the first few percent from 100 seems to drop quicker, but that could be psychological, or due to climate control, even if I have pre-conditioned.

Given what you have said about your commute, the most reasonable option would be to charge to 90% and do two trips before charging. If you want to be more cautious maybe charge to 80% every day? Don't forget that at least in some batteries, discharging close to empty once in a while can help in calibrating the cells. Then again the best advice I can give is that it is your car, so don't let any rando on the internet tell you what to do with it unless you want them to!
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Reuben80
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Post by Reuben80 »

Not a lot to add to what have been already commented, just that you will realise that a battery is dying when it is too late and you cannot fix it. So prevention is best here. Even if you think that it might be a waste of time experiments show what Hondaeboy wrote. It does not hurt to charge at the lower end of the SOC when you can afford it. That is what I do too. 20% to 60% roughly.
For smartphones there is an app called accubattery. It tells you how many cycles you will use when you charge from certain % to %. if you believe in it you will never charge at the higher end of the SOC.
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londiniumperson
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Post by londiniumperson »

Reuben80 wrote: Sun Apr 16, 2023 8:43 am Not a lot to add to what have been already commented, just that you will realise that a battery is dying when it is too late and you cannot fix it. So prevention is best here. Even if you think that it might be a waste of time experiments show what Hondaeboy wrote. It does not hurt to charge at the lower end of the SOC when you can afford it. That is what I do too. 20% to 60% roughly.
For smartphones there is an app called accubattery. It tells you how many cycles you will use when you charge from certain % to %. if you believe in it you will never charge at the higher end of the SOC.
This all depends on your personal circumstances and use case as well as whether you own or lease/hire the car. If it’s not owned outright then the battery degradation is of no concern to the driver.

I understand your comparison to a mobile phone, however the phone and car battery BMS are completely different with the phone system very crude in comparison a car BMS. One clear difference is that a mobile has zero top/bottom buffer.

If you’re happy only having use of 40% of the very low capacity battery then keeping it between 20-60% makes sense, however those of us that need more than 30 miles range in winter couldn’t live with such a limitation.
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
williamchan
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Post by williamchan »

After 0% left on a motorway, I always keep it at least 90% before leaving town.
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