Tip From Duracell: Drain That Battery Completely

But, it’s not just Duracell that says that.  It’s every manufacturer of rechargeable batteries and nearly every manufacturer of an appliance that primarily uses rechargeable batteries.  Taking advice from them is like taking advice from corn farmers about the nutrition value of high fructose corn syrup or from the American health insurance industry about the effects of a national health care bill.  So, then, it’s no surprise that people fall for this one too.  Of course, even with the common knowledge general rule that states, “If a corporation says it, it’s probably false,” that still is not enough evidence to write an editorial accusing them of lying.  So, I decided to dig deeper.

A long time ago, I did an actual battery test.  Unfortunately, we only used alkaline batteries, but we determined that, all things considered, Rayovac Maximum was the best battery on the market in the mid-nineties at the time of the test.  Conversely, Duracell came in last place.  The most popular battery was, all things considered, the worst.  Now, this test was a pain in the arse, and took weeks to do, so imagine if I put lithium ion batteries into that test, and had to do it multiple times to see the effects of draining completely vs. charging nightly.  It would be entirely impractical.  There must be another way.

I never did believe it, but I have a lot of acquaintances (including my best friend) who do believe it and consequently have periods where they can’t talk on the phone because it’s draining.  It got to be annoying, so I knew I had to find a way to search for evidence.  Then, it hit me.  Someone else has probably done the test.  Someone else probably published the information.  So, I did a search.  The first result I found was Geek Squad telling you to do it.  Yeah.  Another non-biased source.   Moving on.

Then I found this website, completely dedicated to the health of your batteries.  With no corporate influence and no incentive to lie to you, they say, “Do not completely discharge the battery, drain only to 0.9 volts.” At the bottom of the page, they then say this:

Common ways rechargeable batteries are damaged

Most damage does not occur through use, but during the charging process. Common causes are:

  • Overcharging the batteries.
  • The charger overheats the batteries during charging.
  • The user fails to exercise sufficient care during the charging process, especially when using a manually operated charger.
  • Using the incorrect charger for the battery type. Particular care must be exercised with alkaline batteries (Primary & Secondary cells).
  • Completing draining a battery. A battery is usually considered flat when it reaches 0.9 of a volt. The normal voltage for a AA or AAA battery is either 1.5 volts (for a Primary cell) or 1.2 volts (for a Secondary cell). Some electronic devices will sense the battery is flat when this voltage is reached and will no longer operate. Others, like torches, clocks and radios will completely drain the battery. Tip: Provided you have not induced reverse polarity you maybe able to recover the battery. Put the Secondary cell in a manual charger for 30 to 60 minutes, and then transfer to a charger with safety features to detect defective batteries. You may not be able to start with a “smart” charger because it will reject the batteries due to no charge. But if you give the batteries a quick charge in the manual charger the smart charger can takeover, but reject batteries that are truly defective. If the battery starts to get hot in the manual charger, stop the charger and throw out the battery. Warning: this technique only applies to Secondary cells, not Primary cells.

So, you might be inclined to take the word of dozens of corporations over one helpful site with no corporate influence, so stopping here would be pretty silly.  After all, you don’t know where the myth came from.  You might just think corporations made it up so you’d kill your batteries faster.  If so, I like your cynicism, but there actually is a better reason for it.  In Marco’s article about the myth, they state that the myth comes from the days of when nickel cadmium batteries had a “memory effect.”  So, what are nickel cadmium batteries and what is the memory effect?

Well, back in the old days of yore, rechargeable batteries were very primitive.  They ran on nickel cadmium.  You might be able to see one of these batteries in a museum somewhere.  They’re certainly no longer in use.  Even if you saved one, it can’t possibly work today.  But, when you charged them, crystals would form around the area where it started charging.  These crystals were known as “battery memory.”  The area where the crystals would form would be impossible to charge again.  If they formed completely across, you would not be able to charge below that point.  It was for this reason, to prolong battery life, you would drain the battery, so the crystals would form at the bottom of the battery, rather than the centre.  But, lithium ion batteries and, more recently, lithium polymer batteries, don’t have this effect, and can be charged at any point.

And, I’m not your only layman saying these things.  The OP in this forum, is a self-professed “battery hobbyist” (whatever that means) and explains again, why you should charge your phone or your camera or your MP3 player frequently, rather than letting the battery die.  Letting the battery die, according to both research and common knowledge, reduces battery life in lithium ion and lithium polymer batteries.  However, he also warns that many mobile phone chargers are designed to “trickle” rather than cut off when the battery is full, so you need to watch your battery to prevent overcharging.  Fortunately for me, all of my chargers can detect a full battery and cut off at that point.  Ideally, in this day an age, this is the type of charger you want for your appliance, because overcharging can also kill your battery.  If you are unsure as to whether your charger is smart enough to stop at a full charge, no matter how full the battery was to begin with, you should be careful with your charges until you get a charger that you know does this.

Of course, remember the rule, “If a corporation says it, it’s probably false.”  And, when in doubt, research independent sources.  Never, never take a corporation’s word for anything.  Ever.  Even when what they say is true, you should have it verified for yourself.  Otherwise, you may end up damaging your batteries.

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There are 10 Comments to "Tip From Duracell: Drain That Battery Completely"

  • MyrtleNo Gravatar says:

    Then you will notice it everywhere, merely simply because folks are genuinely receptive as soon as you exude the Tao Of Badass.

  • Brian KoffordNo Gravatar says:

    I have never seen documentation provided with a lithium-ion battery or a product that uses a lithium-ion battery that recommends draining the battery. Do you have an example?

    • The CeejNo Gravatar says:

      You’re quite lucky. Do you have a mobile phone? Read the manual for that. A digital camcorder? The manual for that. Hell even the iPod’s manual says that. GeekSquad’s website. Phone up your electronics store or phone provider. If you haven’t seen it, you haven’t been looking.

      But, to be honest, I never saw it either until I kept hearing people talk about it. It was when the provider of my last phone told me that I started paying attention, and then Allan wanted me to look into it, and I realised it’s all around me.

      • Brian KoffordNo Gravatar says:

        By example, I mean, can you provide the model number of a specific device that contains this in the manual, so that I can go download the manual and find it there? I have tried looking up the manuals for a couple of items I happen to own, and I could not find this in any of them. If the manual has a page numbers, the page number for the offending phrasing would be helpful, as well.

        • The CeejNo Gravatar says:

          The first thing I tried to do was dig out my manuals for an example, but strangely enough, the manuals for my battery operated appliances seem to have been misplaced. So, I looked online. It seems you’re right. The manuals never said this. It was the corporate reps at the phone provider, the store, and the product call centres (a long list of companies) that said it. So, it seems the problem is not written in the manuals, but passed on by urban legend throughout the uneducated members of the companies. It doesn’t change the fact that the myth continues at the partial fault of the companies, but it does change the fact that I was wrong in it being the official statement. I never paid much attention to battery myths, though, before Allan told me about why he doesn’t “prematurely charge” his phone. The research in the above article was at his request because he wanted to be sure before he charged his phone often.

  • AwesomeNo Gravatar says:

    So do you have to drain the battery to .9 of a volt, or can you just charge it when you feel like it?

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