[Lifehacker article] Simple/cheap way to cut off charging at 80% of battery?

[theilluminati]

http://lifehacker.com/5875162/how-often-should-i-charge-my-gadgets-battery-to-prolong-its-lifespan

As the article says the best case scenario is if you charge your devices when they discharge to ~50% (you have more control on that) up to 80%. But how do you do that? Sure some of you might have smart, expensive clever devices for that end but what is a simple solution for on-the-go or travel situations? Not to mention cheap as well.

 

[Wrend]

So that you're left with a total of 30% of the capacity of a cell to use per cycle?

Sorry, but that isn't a practical nor realistic goal just to try and maximize cycle life and cumulative lifetime capacity potential. Now, if you had exceedingly excessive capacity to work with, and were doing something that was long duration and mission critical, like powering a satellite or space probe of some sort, I could maybe see the rationale.

But to answer your question: Aside from not using an advanced charger to charge the cells individually where you can cut off the charge and/or float charge to a specific voltage, not much. That being said, there are some tricks you could do with relays, or similar, but again, that isn't very practical, nor necessary to get at least decent, usable life from your cells. If you have a "smart" programmable charger, like some of the "hobby" ones, sometimes these will have different settings for Li-Ion and Li-Po cells with different cut off voltages. So for example, the Li-Po charge setting might cut off at 4.2V whereas the Li-Ion charge setting might cut off at 4.1V, and you could just charge a Li-Po cell as though it were a Li-Ion cell (in regards to the charger's settings). This might help prolong the life of a Li-Po cell, but surely cutting off a charge at 80% of full capacity isn't going to be very practical for the vast majority of usage needs, especially if you're not wanting to discharge below 50% charged capacity. 20% or maybe 30% as a low limit, and 95% or maybe 90% as a high limit would seem more reasonable to try and maximize cell life, though still not easily implemented without designing specific charging and device discharging circuitry.

Just remember that the main goal of batteries is to be able to use them (hording for the zombie apocalypse not withstanding). :thumbsup:

 

[theilluminati]

Thank you again for your excellent information (too technical for me; I am a simple user);

OK: to simplify and rephrase my question: say I have a smartphone (or other mainstream gadget); I read in the above and other articles trickle charge is not beneficial and generally kicks in when 'normal' charge charges the battery up to ~80%.

Question: how to cut off the battery from the charger, preferably automatically, if I do not want to watch it?

Practical use: some time you only have time to charge at night, you can't be awake to take off the gadget from the charger, but preferably also do not want to damage it be leaving on trickle charge for the whole night.

 

[theilluminati]

Sorry to bump; any update on this? This would be timely and important; thanks!

 

[BringerOfLight]

There are a number of laptops (e.g. Dell, Samsung, Sony) that have software from the manufacturer to limit charging to 80% or 90%.

For Android phones/tablets, there are some custom Roms/Kernels that allow the same thing. The keyword you are looking for is 'battery life extender'.

Otherwise, the first 80% or so of the charge is fast, the last 20% of the charge is slow. If your device has a reasonable battery gauge, you can guesstimate the required charge time to hit 80 or 90% and use an outlet timer.

 

[reppans]

Another interesting data point (Army Study) on different Li-ion charging habits and capacity loss - dovetails nicely with Battery University. clicky

Use a light timer set to charge early in the AM just before you wake - this minimizes your average state of charge over time.

 

[MidnightDistortions]

I think the maintenance requirements on the Li-ons are just bad but outlet timers are not a bad idea.

The only way i think your going to get the maintenance requirements is to periodically charge it. Even if it's from 60% to 65% that's better than waiting around until 40%. There are plenty of portable chargers, i use a simple AA/AAA USB charger, get a pack of Eneloops and you're good to go providing your device is a smartphone or some tablets i think work with it. If you are using Eneloops Pro or the Duracell (Duraloops) avoid discharging those batteries down too far and you won't need to worry too much about cycle usage. If you do plan on being out for a lengthy period of time charging Li-ons to 100% is not a bad idea and you got 50% to work with.

As lifehacker has stated...

lithium-ion batteries do best when you discharge them for a little bit, then charge them for a little bit.

It's impractical to do this with cellphones (if you're at the store and you only got 70% and can only use 20%) unless you got a portable charger such as the one i suggested. I think most of the other powerpacks with built in batteries are Lithium as well. It wouldn't make sense to turn them off either if not being used so you know if someone tried calling you (they need to show you who called when the cell is turned off).

 

[Kurt_Woloch]

If your device displays how long it will take to fully charge, you could try to cut short the charge after half of the time... or cut it short when there's a specific time left, i.e. 1 hour or 90 minutes, depending on how fast it normally charges up.

 

[theilluminati]

Another interesting data point (Army Study) on different Li-ion charging habits and capacity loss - dovetails nicely with Battery University. clicky

This one might be interesting but complicated; I do not understand. ;(

Use a light timer set to charge early in the AM just before you wake - this minimizes your average state of charge over time.

Neither this.

 

[theilluminati]

I think the maintenance requirements on the Li-ons are just bad but outlet timers are not a bad idea.

The only way i think your going to get the maintenance requirements is to periodically charge it. Even if it's from 60% to 65% that's better than waiting around until 40%. There are plenty of portable chargers, i use a simple AA/AAA USB charger, get a pack of Eneloops and you're good to go providing your device is a smartphone or some tablets i think work with it. If you are using Eneloops Pro or the Duracell (Duraloops) avoid discharging those batteries down too far and you won't need to worry too much about cycle usage. If you do plan on being out for a lengthy period of time charging Li-ons to 100% is not a bad idea and you got 50% to work with.

As lifehacker has stated...



It's impractical to do this with cellphones (if you're at the store and you only got 70% and can only use 20%) unless you got a portable charger such as the one i suggested. I think most of the other powerpacks with built in batteries are Lithium as well. It wouldn't make sense to turn them off either if not being used so you know if someone tried calling you (they need to show you who called when the cell is turned off).

Disclaimer: I am not a native speaker of English but in general (99%+) I understand native speakers. I don't understand your English, however. You might have some interesting points to share but I cannot decipher them; thanks.

 

[theilluminati]

I thought about some other things, added your isights from this topic, the conclusion became: Help Setup Ideal Travel Charger: Crank Charger, 4xAA Charger,USB/Outlet Cut-Off Timer

Thanks for your insights.

 

[reppans]

This one might be interesting but complicated; I do not understand. ;(


Neither this.

The Army study tested samples of 18650 Li-ions cycled under 4 common charging habit scenarios to determine the effect on the cell's life (capacity loss). Top-off 100-50-100, deep discharge 100-0-100, middle of the road 75-25-75, etc.

The bottom line that they found, and which agrees with what BatteryUniversity says, is that max charges and higher avg SoC (state of charge) are the most taxing on batts, and secondarily, deeper discharges are more taxing than shallow discharges. Contrary to popular belief, running the cell to near zero SoC actually prolongs it's life through lower avg SoC.

On the second point, if you plug in your batt to charge before you go to bed, it will quickly hit its charge target (eg, 80%), say in an hour, and then it sits there all night contributing to a higher avg SoC. However, if you put it on a light timer ("outlet timer" - whatever) to commence charging at 6am (and so terminates at 7am just before you need it) then the batt sits at low voltage all night contributing to a lower average SoC.

Hope that explains it.

 

[markr6]

On a normal day, I only use about 20-30% of my iPhone 6 anyway. So I always charge it anywhere between 40%-60% and stop charging around 90%, unless I'm busy or forgot. I don't make a big deal out of it; just check it since it's sitting right in the open in my kitchen.

 

[MidnightDistortions]

Disclaimer: I am not a native speaker of English but in general (99%+) I understand native speakers. I don't understand your English, however. You might have some interesting points to share but I cannot decipher them; thanks.

Too technical?

I guess my Engrish could be pretty hard to understand even with a light. :candle:

I'll try a tl;dr comment. If you do regular 5 minute charges on the phone keeping the charge level around 70-80% you should have no problems. Does that help? 😀

 

[Illum]

If you really must use a cut-off [and I have no idea why one would], there's three ways go go about it. A decision can be made based on one of three measures: Voltage, Current, or Time. I don't know how to explain the rest without being "technical"

 

[poguy]

For a phone get one of those USB voltage/current meters. I unplug when charge current goes from .6 amp to .2 amp or so.