justthisonce Loc: Tetepare

Pro tip regarding batteries in general:

Alkaline and lithium batteries discharge in significantly different fashions.

The output voltage of an alkaline battery gradually drops as the battery discharges. For example, the output of a 1.5v AA cell will gradually decline as the battery discharges. Think of how a flashlight gets dimmer as the battery is depleted.

The output voltage of a lithium battery remains virtually unchanged until the battery charge is, essentially, totally consumed. The flashlight will remain at a constant brightness until it suddenly goes dark.

Why would you care about that?

Consider this: you have a 6-volt battery powering an electronic device with circuitry that requires, say, a minimum of 5.1 volts for it to stay functional. Using an alkaline battery, once it is discharged to 5.1 volts the device stops working even though the partially discharged alkaline battery still has "some life left."

In contrast, a 6-volt lithium battery will continue to produce 6 volts and keep the device operating until the bitter end and the last of its charge is depleted.

So, if you're replacing, say, 1.5 AA alkaline cells in something like a modern security camera or trail cam that has a minimum operating voltage limit, you can save those "dead" batteries and use them in your flashlight, remote controls, and so forth.

Longshadow Loc: Audubon, PA, United States

My Sony H1 is like that. Can't use alkalines in it, won't even last 1/2 a day, but the batteries are still good. I have to use the Li-ions.

47greyfox Loc: on the edge of the Colorado front range

I’ve heard from countless (credible) sources that lithium ion batteries like in mobile phones should be discharged no lower than 15% and charged no higher than 85% to prolong life.

Longshadow Loc: Audubon, PA, United States

Credible like Tony what's-his-name?
The battery for my old cell phone was maybe 10 years old.
I let it charge all the way....


(I heard it through the grape vine (internet).....)

BebuLamar

There isn't a 6V lithium ion battery. Fully charged a 2 cell Li-Ion is 8.4V. They drop down to 7.4V as you use it. If the 2 cell Li-Ion battery voltage is down to 6V it's dead. If you discharge it further than that you can cause damage to the battery.

Stephan G

Speaking of relative, the fuel indicators on all cars are relative. More accurate would be "Can Go" and "Cannot Go". Notated at the factory.

Longshadow Loc: Audubon, PA, United States

I have 10-12 "notches" (bars) in my car.
So one might think, gallon capacity / bars = gallons per bar.....but,
what if the fuel tank is tapered?

*Full
*Keep Going
*Fill me

Drbobcameraguy Loc: Eaton Ohio

On a phone the phone software controls the charging. The charger just supplies power

Drbobcameraguy Loc: Eaton Ohio

On a phone the phone software controls the charging. The charger just supplies power

TheShoe Loc: Lacey, WA

It depends on the type of battery. The 20-80% applies to Lion batteries. The other, with slight alteration, was true of older batteries.

marvkaye

The battery management circuitry & software in modern cell phones is optimized for LiPo batteries in ways that let the user not have to worry about running the battery down too far and/or overcharging. When you run your phone down to 0% in reality the LiPo is still charged to about 3V. If you don't charge it and let it sit it can go to zero volts over time, but it does take quite awhile... think weeks to months. You won't really know how much below 3V it's gone because to the phone that 3V is zero and it won't even turn on until it comes up to 3.2 or 3.3 volts anyway. On the charging side, LiPos use a two-stage charging method that starts with a constant current, then switches to a constant voltage... the charge controller built into the phone knows what battery is being used so its charge profile is setup specifically for it in order to best maintain its health and longevity. During the process the battery is monitored not only for its charge but its temperature as well... again, all managed by the built-n charging system. In other words, you really shouldn't have to worry about charging or discharging your phone... they're built pretty much for the unwashed masses who mostly couldn't care less about managing how they charge them, they just want to use them for all the things they use them for.

Longshadow Loc: Audubon, PA, United States

That's what I would have surmised, the optimum charging control is designed into the unit. Not like the designers have no idea of the battery characteristics...
Otherwise people would be replacing batteries left and right, dying from "over charging"...
Probably 99+% of the people let the batteries charge until the indicator says "100%".

I'll continue to let the charger indicate 100%.

Stephan G

I listen for the "Burp".

Longshadow Loc: Audubon, PA, United States

JoeBiker Loc: homebase: Houston, TX

I agree: "Only the manufacturer knows for sure.", and 100% is the level that the manufacturer decides to stop charging it at. Also, I am talking about Li-Ion batteries, not NiCad/NiMH as the original advice was for.

The problem is there are conflicting priorities. If the battery is charged to a higher level, it puts more strain on the battery and the usable lifetime of the battery (measured in years, or number of charges) is reduced. BUT, it provides the long "Battery Life", as in minutes of use per charge. I can tell you from experience that there is a lot of pressure from the marketing folks to be able to claim the longest battery life, and they don't worry too much about the usable lifetime of the battery (that can't really be advertised).

On my Android phone, I have a battery widget app that I setup to chirp when it reaches 85% or 90%. If I am around when I hear that (and I am just going to be around my house), I unplug it. If I don't hear it, I don't worry about it.

There is not much I can do about my Laptop, it spends most of its time plugged into the wall, and having it cycle several times between 20% (or whatever) and 80% would age the battery more than just charging once and letting it sit fully charged.

I would like to know which laptop brand therwol uses that has a setting to only charge it to 80%. Our battery engineers would never have gone for that, for several reason: Twice as much testing and twice as much opportunity for something to go wrong, and most customers would just be confused by the choices anyway.