Rockbox Development > Feature Ideas

Battery Protection

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Lope:
Li-Ion Info
Li-ion batteries generally only last 300-500 charge/discharge cycles.
Deeply discharging them or leaving them in a discharged state significantly reduces their usable capacity/lifespan.
To get the most of my Li-ion batteries for portable devices, (laptop, mp3 player etc) I don't discharge them lower than 40%, and if I really need to I won't go below 25%, or 15% at the very lowest. (thats only on a laptop if I NEED to do something.)

Feature (when enabled)
When you hit 40% automatic shutdown is initiated, where you have to press a button to cancel the shutdown.
At 30% it happens again. Then it happens every 5% after that.
Another option to force shut down at a preset battery level (incase someone borrows your player, you can prevent them from deep discharging it)

http://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

dreamlayers:
As long as you don't go below certain minimums, does deeper discharge really wear out Lithium-based batteries faster?  Shouldn't the normal automatic shutoff point already be high enough?

For example, how does battery wear at 0% to 50% cycling compare with battery wear at 50% to 100% cycling?

I suspect that 50% to 100% cycling will wear out batteries faster.  I've seen several graphs which show that charging to a higher voltage increases wear.  It's also a well known fact that these batteries wear out faster if stored at higher levels of charge.

So, if there was some battery life extension option, maybe it would be better if it stopped charging before reaching 100%.  Just note that not all targets allow charging to be shut down by software.

At the moment I don't really care much about this.  It doesn't seem like the batteries wear out too fast.

soap:

--- Quote from: dreamlayers on November 20, 2010, 09:08:23 PM ---So, if there was some battery life extension option, maybe it would be better if it stopped charging before reaching 100%.  Just note that not all targets allow charging to be shut down by software.

--- End quote ---

This is what my Toughbook does when it is hot to be kind to the battery.
One has to go into the BIOS and ignore a warning to enable full charging in hot environments.

As I Understand it, heat is the enemy.  The top of the charge cycle produces the most heat, and a 0->90% charge produces more heat than a 50->90% charge.  Now if 50->90% charge x2 is worse than a 0->90% I do not know.

But, yea, I'm ending year five now of my iPod's original battery and am just now thinking about a new battery.  I'm down to around 75% capacity after what I can only estimate to be well over 500 charge cycles.  Likely pushing 1000.

torne:
I don't think the original poster has quite the right idea even from the article they linked.

Our shutoff voltage is just fine, as long as you don't discharge to what we display as 0% and then leave the player like that for an extended period of time (the self-discharge will eventually kill it). Our 0% is not a deep discharge; it's a discharge to the point where the player's regulators don't provide enough output current any more, which is a healthy margin above where the battery will take any damage.

It's true that running the battery all the way down before recharging (what people used to do to avoid "memory effect" on older tech) shortens the life compared to topping it up more frequently, but the actual difference is not something you will really notice. The best way to use a lithium based battery in a modern consumer product is to charge it whenever it's convenient for you to charge it, and use it whenever you want to use it; imposing restrictions on how you use the device is going to reduce its utility to you much more than it improves the life of the battery.

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