Train a battery?

December 11, 2007 9:18 AM

My wife has insisted for some time that you can 'train' a battery in order to optimize its performance and lifetime.

For example, with a cell phone battery, she says it is best to let the battery run out almost completely before recharging it. (as opposed to plugging it into the charger whenever not using it, which is what I do). Bullfeathers, I say. Sounds like an urban legend.

I've tried searching the web, including snopes, but can't find anything on the subject.
Can any one help?

posted by allelopath to Technology (14 answers total)

That was once true with old NiCad batteries (they had to be massaged a certain way), but modern lithiumion stuff doesnt work this way. There's a microcontroller than manages the battery anyway. Any tricks at this point is psychological.
posted by damn dirty ape at 9:21 AM on December 11, 2007

You're not going to find a one-size-fits-all answer for this question, as best practices vary with battery type.

For example, I've been told that running lithium ion batteries all the way down before recharging actually shortens their lifespan. But Nickel-Cadmiums are exactly the opposite.
posted by JaredSeth at 9:26 AM on December 11, 2007

Here's a table that describes how you should charge different types of batteries.
posted by burnmp3s at 9:29 AM on December 11, 2007

The answer is thta it depends on the type of battery. For NiCd and NiMH batteries, it's better to discharge it fully to avoid "memory" and prolong the life of the battery. For lithium and lead-acid batteries, it's best to charge frequently.

Source: the excellent Battery University site.
posted by TungstenChef at 9:34 AM on December 11, 2007

Doh, beaten to the punch by burnmp3s.

*shakes fist*
posted by TungstenChef at 9:34 AM on December 11, 2007

>>it's better to discharge it fully to avoid "memory"
memory of what?
posted by allelopath at 9:45 AM on December 11, 2007

Here's another article from Battery University that describes the "memory" issue in depth.
posted by burnmp3s at 9:51 AM on December 11, 2007

Apple dedicates a whole section of their site to information not just about how to conserve battery life, but how to properly condition the battery as you charge/discharge it.

Short answer: Not an urban legend. Depending on the type of battery, your wife is right.
posted by aparrish at 9:52 AM on December 11, 2007

Depending on the type of battery, your wife is right.

Depending on the type of battery, your wife is wrong.
posted by chunking express at 10:23 AM on December 11, 2007

memory of what?

Let's say you frequently let your NiCd battery drain to about half before recharging, instead of letting it drain completely. After awhile, what happens is the battery will ultimately stop working when it's down to half charge -- in a manner of speaking, half will be the new empty. Thus your battery runs half as long on a full charge now as it did when it was brand new. Gradually that life span gets shorter and shorter.

Someone once explained why to me, but damned if I can remember.
posted by middleclasstool at 10:47 AM on December 11, 2007

The Wiki on it.

I've been in a few arguments with my brother about this (he's an industrial electrician). He lets every kind of rechargeable cell run down to minimum spec, then be charged fully, at least twice before general use. Something about "burning" the memory (burning may not be the term). Even though Lithium ion batteries should not have this problem, he swears by it, and apparently it is standard procedure.

Although to be sure, Lithium ion batteries don't go to a null charge before the voltage becomes unusable, so JaredSeth's problem doesn't affect this.
posted by dr. moot at 11:17 AM on December 11, 2007

Memory in batteries is 99% bunk, it's a lab only phenomenon, what people think is memory effect is usually just a battery wearing out, as they all do.

Read a no bullshit explanation:

HERE
posted by Cosine at 12:18 PM on December 11, 2007

It certainly isn't memory, but there are other issues that might look like memory.

In particular.. Overheating batteries decreases their life. Attempting to charge batteries beyond their rated capacity will cause overheating. Many low quality chargers either charge continuously or for a fixed amount of time. If the fixed time period is a full charge cycle, then you will avoid overheating by completely discharging. If the charger works continuously, then you are more likely to avoid overcharging by completely discharging, only charging for a fixed period of time, and then storing the device off the charger.

That, and as Cosine says, they all wear out.
posted by Chuckles at 12:30 PM on December 11, 2007

Lithium Ion batteries last about two years from date of manufacture, regardless of how (or even whether) you use them.
posted by flabdablet at 2:32 PM on December 11, 2007