I may be one of those over-thinking but this is how I think about the 80-20 rule. (which is still believe to extend battery life?)
I don’t find it taxing to stop charging at around 80%. It’s easy with a timer.
It’s not just a matter of me being unwilling to buy a new $1.000 battery but of course I want my battery to last for a long time.
I want my battery capacity to stay on top as long as possible so that I have the same range over a longer period. I don’t know how fast batteries degrade but I want to postpone the day that I may have to reduce the distance I can go on a full charge.
Charging to 80% is luckily for me very often enough for a day ride. Not always so sometimes I give it a full charge (and also balance the cells I hope )
But I like a fully charged battery. The difference in power is noticeable
I completely understand. However you need to understand that you may be talking about a difference of 5 to 10 percent, give or take what degradation you're going to get regardless. So for the average bike you're talking a couple of miles. If that's the difference from making your trip or not you're cutting it too close in the first place, which it sounds like you're not. It's rather akin to putting 10 gallons in your car gas tank and calling it good. I'm okay with that as well. But when I have a big trip I fill it all the way up.
Most of the batteries are costing half or less than that. Surely yes some proprietary types are upwards of a grand. Also know that domestic rebuild shops are popping up with will be able to install new cells in your pack for much less than a replacement.
So sure, putting it on a timer is fine if you want to walk away, I get that too. But it's just a best-guess charger time to target your SOC anyway. You may or may not even be close to your intended target.
What we're saying in a round about way is that it's a lot of machinations for very little ROI on the effort. YMMV And of course you can do whatever you want. I'm a big-picture guy, and while detail oriented, I have way too many irons in the fire than to worry about extending my ebike battery for a couple of miles. In fact, it costs me about $50 to write this reply.
It may well be that my concern is tempered with my frequency of charge cycles - I'll be lucky if our bikes see 50 of them in a year. So it's gonna take ten years for me to reach 500 charge cycles. Hell, I may well be dead by then anyway.
Now generally as far as these power packs go, look at it this way...
Do y'all have a cordless power tool of any sort? Drill motor, saw, dust-vac, etc.? Or your cell phone, laptop, or tablet?
They all use lithium-ion batteries. I chose my iPhone 6-plus for it's battery capacity - large form-factor means large battery. I just plug it in to charge every night, regardless of it's SOC (state of charge), unless it's above 80%, then it will likely get me through the next day. After four years it is still at 90% capacity, and I think Apple knocks them down some just with OS updates to encourage users to buy new. Plus you can buy a new battery for them for less than $10, are relatively easy to install. Replacements for laptops and tablets are not generally a huge investment either - if they won't hold a charge well any longer just get a new one.
Same for my dust-buster - it sits on it's charger 24/7 unless I use it, then sometimes it will run out to empty and quit, put it back on the charger-mount. It really doesn't care, it's always ready to go when I need it.
My power tools will lose some capacity over several years because I pay zero attention to their SOC. I use them 'till they quit, then put the battery on the charger and charge them all the way up. I think I've only replaced one cordless tool battery over the years, and that is likely from just simply failed cells. The rest of them just keep going and going and going.
If these were lithium-polymer, of which I'm even more familiar, I would be a lot more adamant about battery care - they are nearly explosive if not properly cared for. But Lithium-ion batteries are really stable, are charged at a very low rate, have no memory effect, and don't blow up if you charge them all the way up.
Don't worry - be happy. Charge up your ebike and go enjoy it. If you're worried about it, throw $10 a month in a 'battery fund' to buy a new one a few years down the road when it no longer performs satisfactorily. It's going to take a long time before it won't do the job any longer, unless it's just junk to begin with. Yes, some of them are rather expensive. My bet is we'll see costs coming down over the years, and dramatic performance improvements, and your ebike today is very likely to be completely obsolete in a just a few short years.
There. My worthless 2cents on the subject. I'm going riding.
