Stop Charging When Power >80%, Start When <=40


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Let's put this another way, to do what you want to do the charging circuit would need to support it, as well as your BIOS and a driver and software in Windows written to control the circuit. You could perhaps "roll your own" using a relay, and an Arduino. The Arduino would constantly be fed the battery percentage from Windows (you could write your own software in or C# to report this number to the Arduino via serial communications). Once the Arduino see's the number is 80 percent or greater it would trigger the relay to turn off the relay thus disabling the AC adaptors ability to charge the battery.

This is actually not a hard project at all, if I thought there was a mass need/want for such a product I'd make it, but I really think it's not that important. Batteries are around $15 anymore, and as long as you're not keeping your battery insanely hot, and calibrating it every 3 months or so I'm not sure the loss is such an issue as you might think. I've had the same battery now in my Lenovo Yoga 13 for years now and not noticed a major change (and I keep it charged 100% most of the time).


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If you don't want to learn how to use relays, learning how to do a simple project like this using an mini Arduino and a product such as this controllable outlet shouldn't be too hard

Also here's a video (even though it's Linux and using bash/python) showing the concept. Could easily be adopted to Windows using C#/VB etc..

If you use a TinyDuino the Arduino portion could be shrunk down to the size of a quarter, and if you rolled your own relay PCB it could be much smaller than the product I showed above. (just make sure you do your homework and get a relay rated for the right voltage!)



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The battery for my Alienware 17 was $65 for a no-name product and about $120 for a branded version.
The original battery was completely dead after just over 2 years. Of course the notebook was running around the clock and averaged 35-40 degrees Celsius.

I expect the battery price for my new HP Omen 17 to be similar.
And the battery is sealed in, and difficult to replace. God knows how much it costs to replace if you bring it to a service center.

Still, I'll probably go that route rather than solder around with an Arduino and learn VBA :)

But if you were to program a power supply to shut down at a certain charge level, you'd have to keep the charge/discharge cycles as shallow as possible and at around 40%, lest you avoid calendar aging but cause cycle aging instead.
Cycling between 40-45% would probably be ideal. At this level, there should be essentially no wear from battery cycling.
Cycle aging is affected by two factor: 1) depth of discharge and 2) terminal state of charge.
Charging from 0-100% causes about twice as much wear as charging from 0-90% and four times as much wear as charging 0-80%.
From studies I have seen, a lithium-ion battery that will cycle 500 times from 0-100% will cycle maybe 20.000 times from 30-70%.

For my Galaxy S7, I have a charge level alert that tells me when the phone reaches 80%, at which point I will disconnect it :)


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If you studied the ROI for dollars and time spent on this sort of thing, I believe if you showed it to the Shark-Tank folks on TV, they would show you the door. Every solution has a problem, but for most laptop users, Josephur's solution would be way over the top. They don't even like carrying around a mouse-dongle for an external mouse let alone a small circuit board and a 2nd AC adapter in there.:noway::rolleyes: And, for many laptop users who are forgetful, they forget their AC adapter (the one that powers the laptop), their external mouse, USB flash drive backup, etc. when they show up to a place outside of their home with their laptop.:rolleyes: This happens all the time with students in my Classes, and just yesterday as a matter of fact, one lady in my Class knew she was coming to a class where she needed her laptop and all her accessories, but could not remember to bring her mouse since she couldn't use the built-in trackpad.:rolleyes: What if she had this external circuit board and a 2nd AC adapter to carry around too, think she would have remembered to bring that also?:( It's an ingenious solution to a tricky problem, but how many people of a billion laptop users would actually use something like this to save $15-$35 for a new replacement laptop battery? Not many, is my guess.

Buying a laptop without a self-servicing type battery, is just asking for trouble IMO. Especially when it's been well established here and elsewhere that 95% of batteries from the major laptop makers fail within 1-2 years, and even less if they are installed in Gaming laptops such as Alienware-Dells or MSI.:waah: This is like many new Cell phones which did away with the ability to open the case and remove the battery--this is stupid IMO and I would never buy a phone without that capability. I just had to make that decision last December when I bought my latest Cell phone.


After thinking about I've decided not to remove the battery whenever I don't need it, putting in additional RAM was an ordeal in itself and I'd have to reset the time & date each time. The letter point can largely be ignored, but I just don't want to put in and out countless screws each time, thanks anyway.
My lenovo yoga 510 come with new feature that able me to switch the battery to only charge up to 60% when battery not in use, so that I don't overcharging it to offten and damage the battery lifespan. But for those who don't have this feature their alternative free software to download and install which you can set the battery limits and notify you to use the mains supply or battery supply and prevent overcharging and prolong the battery lifespan... limiter

Battery Limiter:
Sometimes your battery might be under a lot of stress running towards the last percentages of its full capacity while charging Battery limiter is a simple, small software that will help you and alarm you when charge capacity hits the limit. So you'll never forget to unplug your laptop again.

Note: If you have to reset the time & date each time remove laptop battery then you need to replace the internal bios battery inside your laptop.

I dread having to replace the battery in my Toshiba L55-A5226. I have use of only my right arm and the bottom cover needs to be completely removed to get at the battery. It would probably need to be replaced by a technician, which will cost extra $$.
Right now, the battery seems OK. The charging automatically stops at 80% and I rarely ever use the laptop on battery alone.

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