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Power Science

Memory Effect Discovered In Lithium-Ion Batteries 157

Posted by samzenpus
from the a-little-less dept.
rwise2112 writes "Lithium-ion batteries have long been thought to be free of the memory effects of other rechargeable batteries. However, this appears to be not the case. Scientists at the Paul Scherrer Institute PSI, together with colleagues from the Toyota Research Laboratories in Japan have now discovered that a widely-used type of lithium-ion battery has a memory effect."
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Memory Effect Discovered In Lithium-Ion Batteries

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  • by toygeek (473120) on Monday April 15, 2013 @02:00PM (#43453831) Homepage Journal

    I've always wondered why they say that Lithium Ion and Lithium Polymer batteries don't have a memory effect, when even laptop batteries based on those technologies die after several years, and NOT because of charge cycles. I'm talking about the ones that stay plugged in most of their lives, charging. Maybe its the lack of charge cycles that kills them? But to say Lithium batteries have no memory effect has always been ludicrous to me.

  • by afidel (530433) on Monday April 15, 2013 @02:01PM (#43453845)

    And I wouldn't call LiFePO4 "widely used", it's hardly used at all in the west due to extremely high royalty rates charged by the patent holders. I'd actually love to use LiFePO4 cells for my camping solar setup but the only ones I can find are dodgy Chinese imports with questionable charge controllers.

  • Which is actually a very uncommon form of li-ion battery. Military drones use it, the batteries are taken out of service after just a few charge cycles.

  • by Maximum Prophet (716608) on Monday April 15, 2013 @02:12PM (#43453943)
    With any battery technology, it's almost never the "Memory Effect", but simple overcharging. If your laptop batteries are always hot just sitting there when the laptop is plugged into the mains, they won't last as long as ones that are properly charged and left alone until they are needed for discharge. With cheap cordless drills and other tools, simple putting a timer on the charger will greatly increase the number of cycles you can get out of the batteries.
  • by Anonymous Coward on Monday April 15, 2013 @02:23PM (#43454067)

    "
    Batteries should be stored in a cool location. Keeping a battery in your notebook for long periods of time when running off of AC subject it to high temperatures and a shortened lifespan.
    "
    Nope, that's not the reason.

    Typically, a new laptop owner does the following.
    Buy new laptop
    Install battery (if it's not already)
    Place on desk.
    Plug in to AC power.
    Use for 5 years or less, and never move it from that spot.

    In other words, the battery is NEVER used.
    I've seen it personally with the last 3 business laptops I've had (hp, lenovo, dell) as well as the past four personal laptops i've sold to people. Those that actually use the battery down to zero at least once a month? Batteries last forever.
    Batteries never actually used, but the laptop runs on AC power with the battery sitting there doing nothing? 100% of them will not hold a charge of any kind after 12 months of this "non-use".

    Back in the 90's, there was Windows (3.11, wfw, NT, win95, win98) software available to exercise the battery while it was plugged into AC power. Such software allowed even ni-cad's to last for years without developing "memory" or losing run time. It allowed you to schedule a full discharge of the laptop battery weekly or monthly. Such software was also available for UPS's at the time. (Remember those UPS's that actually would run a computer for hours instead of minutes, yeah, those ones)

    Since then, all such software has disappeared, and what do we have? Completely useless batteries in both laptops and UPS's, in under a year.

    It's the same trend as printers and power tools. Consumables must cost more than the original unit and/or fail every year, minimum. Inkjet cartridges? Check! Power drill batteries? Check! Color laser printer toner? Check! Laptop batteries? Check!
    When things in the PAST are worse than things in the PRESENT, and they perform the same task, it's not the advancement of technology that is to blame.
    It's sociopath-run businesses wanting to turn everything into a service with an annual fee. Go-go-gadget free market consumerism!

    My personal experience with laptop batteries has been that if they are fully/completely discharged to zero at least once a month, they last forever, regardless of all other usage patterns, elevation, humidity, temperature, make, model, or cell count.

  • Re:No Shit (Score:5, Interesting)

    by BitZtream (692029) on Monday April 15, 2013 @05:35PM (#43456143)

    No one with any actual understanding of batteries said Li-Ion does not have memory.

    What was said is that: From a practical perspective, Li-Ion memory is not an issue to worry about.

    The article is basically someone who just did a study to confirm what probably every battery manufacture on the planet knew about Li-Ion at least 15 years ago. Longer I'm sure, I just have no experience before that.

    What they did was took something they interpreted incorrectly, and then did a bunch of research to disprove some statement they misheard.

    This is roughly like me telling you the surface of the earth is flat when you're building a small house, and then having a bunch of morons who overheard our conversion from 3 tables over do a study to determine that no, infact the Earth isn't flat. Of course its not flat, but from a practical perspective to the man building his home, its flat.

  • Re:No Shit (Score:5, Interesting)

    by Tobia Conforto (2818827) on Monday April 15, 2013 @05:45PM (#43456225)

    Yes shit. People who "use Li-On[sic] batteries and have to charge them frequently" are simply incurring in an unfortunate characteristic of Li-ion batteries, namely that they have a finite number of recharge cycles, or equivalently, that each recharge cycle diminishes the total charge the battery can hold.*

    This has nothing to do with a memory effect.

    For comparison, Ni-Cd batteries (as seen for example on power tools) have a strong memory effect, meaning that if you plug them in before they are exhausted, they "remember" the smaller capacity you've used them for, and it takes a number of complete discharge and recharge cycles to restore their full capacity. Of course, all that's needed to fully utilize Ni-Cd is a slightly more expensive charging circuit that fully discharges the battery before switching to recharging, which is why they are widely used in professional applications.

    _____________
    * Battery-savvy users always keep their mains plugged in on Li-ion devices such as laptops, so that the battery undergoes few recharge cycles and still performs as if it were new when they need it to, even after years of usage. But not after too many years, because Li-ion also have a limited timespan, or equivalently, the total charge they can hold diminishes every second since they leave the factory. Yes, it's a complex world.

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