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How important is battery life?

Discussion in 'Headphones, Earphones & Portable Music' started by chrisss, Feb 27, 2005.

  1. chrisss

    chrisss
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    I want to buy a 20gb HD DAP next month. Money is tight so reliability, robustness & longevity are important as well as sound quality. From reading the posts here it would appear the first thing to go on a HD DAP is the battery which has an average lifespan of 400 recharge cycles. Does this mean that the Sony NWHD1&3 & the Zen touch should last the longest as they have the longest play time between recharges? Or am I missing something here?

    Chrisss
     
  2. Pecker

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    I think a lot of people have said that battery life is never what is quoted, unless you use the unit in abnormally static conditions.

    So, a 12 hour battery will rarely last 12 hours, and a 6 hour battery will rarely last 6 hours.

    But a 12 hour battery will regularly last you twice as long as a 6 hour battery.

    What/how/where do you want to use the unit?

    If you need to go to work for a 40 minute journey each way, you probably don't need to worry - the battery won't give up that quickly.

    But if you think you'll need the unit for extended periods of time, and are worried that the 12 hours quoted (or 6, or 8, or 24) won't be long enough, then go for the longest battery life you can.

    If you contact most manufacturers, they should tell you how many charges the battery should last for, if the information isn't up already at their sites.

    Finally, if money and reliability are issues, consider that some units have replaceable batteries, and some don't. My unit (Zen XTRA) has a replaceable battery. If it 'goes' a replacement is less than £30 - you can buy one by post/email/'phone, and it'll be with you within a couple of days.

    If your battery 'goes' and the unit is out of warranty (and the battery isn't user replaceable), you'll have to return the entire unit, at your cost, and buy a new battery, again at your cost. And that'll be far more than £30.

    This isn't a reason to buy/not buy certain units, as everyone will have their own criterea, wants & needs. It's just something to consider.

    Check it all out at the companies' websites before you buy, and decide for yourself, based on the facts.

    Steve W
     
  3. mick's cat

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    Just be careful where the information you get comes from. There's an awful lot of rumours floating around regarding DAP batteries but actually not many facts. Here are the undisputable real facts:

    * lithium based batteries are best not run down too far anyway, so the fact that one DAP lasts so many hours longer than another is irrelevant. The only way to keep them in good condition for as long as possible is to keep them topped up as often as you can get to a charger unit or base station. So even if your DAP would last a fortnight before total discharge under your normal usage (which the NW-HD3 probably would under normal usage), it's best to charge it up every day anyway. Even if you don't use your DAP for a few days or weeks, it's still best to keep it topped up every day. Without this regular daily charge, the battery will die sooner than its natural life (see below). The average 400 cycles that all manufacturers will quote is nothing to do with the manufacturers, it's just a fact of life lithium batteries.

    * there is a single exception to this when a DAP features a 'battery gauge' type of display to indicate battery level. Such displays need to be re-calibrated regularly to keep the display in tune with the actual battery contents. The only way to do this is to totally discharge the battery every 30 or so charges - ie, once a month if you keep the battery topped up daily as you should.

    * aging is the aspect that defines natural life. Lithium ion batteries only last 2 or 3 years before the internal resistance builds up to the point that it cannot fully release its energy, whether you use them and keep them topped up daily, or use them only monthly. So there's no point in buying a spare battery now in case the one you use dies - they'll die together, regardless.

    So, in short, buy what you want according to the DAP's specs, not on what you hear regarding battery life. All DAPs use lithium batteries so have the same limits, regardless of their quoted battery life. In a maximum of 3 years you'll be needing a replacement battery, so it's best to buy one from a company who you know will still sell you a replacement battery.

    Anyone who tells you different to these facts is merely rumour-mongering.

    One of the clearest sites I've seen regarding batteries (not too technical so even the the rumour-mongers can understand) is the Battery University:

    http://www.batteryuniversity.com/
     
  4. mick's cat

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    Oh, I forgot...

    Temperature is an important factor too. The warmer a lithium battery is, the shorter its normal lifespan ie. it ages quicker so won't achieve its normal 2 to 3 year life. So, ideally, don't keep any player with a lithium battery (in other words, any of them) in your first-layer clothing (say, your jeans) pocket - instead use a belt clip or similar.

    All figures for lifespan and battery life are defined by a standard failure rate ie, all batteries succumb to failure according to a normal distribution, commonly called a 'bathtub curve'. In other words, a small percentage will fail in an 'early period' of less than 2 to 3 years, a small percentage will fail in a 'wear-out period' which happens to be greater than 2 to 3 years, but the vast majority will fail within the 'useful life period' which is the 2 to 3 years quoted by battery manufacturers. That's why you hear of people whose batteries have failed after only 18 months, and that's why you hear of people who still have a 3 year old DAP which is still going strong. They are the exception, not the norm.

    OK, if anyone's still awake :boring:, just remember I'll be testing you on all this the next time the question of battery life arises... :)
     
  5. diverse

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    battery life is important if you want to use the unit via batteries! Not so if you never will leave the comfort of a wall socket ;)

    The Sony will not dissapoint you!
     
  6. chrisss

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    Thanks for the lucid and informative replies. I hadn't fully appreciated the finite lifespan of the batteries irrespective of the number of recharge cycles.
     
  7. mick's cat

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    Um, yeah, but that wasn't what I said. I'm sorry for being so long-winded that you missed the point. Maybe an analogy would help?

    Smoking. It's a fact that if people smoke, average life expectancy is lowered. Stop smoking, and you live longer. It's the same with batteries. Don't keep them topped up daily, and their average life expectancy is lowered. Top them up daily, and they live longer.
     
  8. mrtbag

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    Where do manufacturers quote 400 cycles?

    That is not true of 'Every' Li-ion battery. Even the site you list clearly states:

    and
    So yes, Li-ion batteries frequently fail, but so fo other types of battery. It's more a 'battery' thing, that a Li-ion thing.

    Regardless of what type rechargeable battery a DAP uses, this would still be true.

    :rolleyes:
     
  9. mick's cat

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    Yes, that's absolutely right, and I'm not arguing against the use of lithium batteries at all. I certainly didn't say that lithium batteries are any worse than any other, and I'm not sure where you got that impression from. They are after all the only choice of battery for the situation (no other battery type could do the job at all). All DAPs use lithium batteries, but lithium batteries will die after a certain time - that time can be extended by prudent usage. I'm only suggesting the means whereby users can get the best life.
     
  10. mrtbag

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    Granted. But your last post suggested all Li-ion battery WILL die after 2-3 years.

    This is not a proven FACT with every single Li-ion, and you did list your statements as FACT.

    It is pointless to give advice on one hand that says 'Do this and your battery will last longer', yet on the other say 'It'll die after 2 to 3 years anyway'.

    That would indicate that you mean ' Do this and you may get 2 to 3 years, don't and you won't get 2 to 3 years'. That is a statement I'd find hard to accept.
     
  11. mick's cat

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    No it is fact. We seem to be arguing at cross-purposes here however. If you read the thread fully you will see that when I talked about failure rates and the resultant bathtub curve that there is a reason for some lithium batteries to last longer than 3 years, and equally there is a reason why some fail before 2 years. It's a simple fact of product life - any product, not just lithium batteries - some will last longer than others, and that there is an average lifetime for *any* product. Lithium batteries are no different to any other product. The average lifetime for *all* current lithium batteries just happens to be 2 to 3 years. I'm not saying, and never did, that 3 years is the maximum though. I'm sorry that you didn't understand that, so apologise for not making it clearer.
     
  12. mrtbag

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    Firstly, I have read the thread fully. The only post of yours I have an issue with is the one I quoted.

    Mick, I can't be any clearer on this.

    Your post:

    IS NOT FACT

    Now you have included the words 'Average lifetime' there isn't an issue. I just feel that you cannot post information where you state it's fact, and it's not. (especially when always accusing others of 'rumour-mongering').

    It should also be pointed out that the site you refer to was created in 2003, and even some of the newest articles are from early 2004. Technology has moved on already from there. I'd say you can now forget the 2 year part, and say Li-ion battery last over 3 years on average
     
  13. mick's cat

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    OK, I now see what you mean - forgive me for the omission of the word average in that paragraph. Average lifetime. OK?

    I must say in all this that you've only confused the issue though. My whole point is to say that lithium batteries *have* a limited lifetime (average or otherwise), and suggest how to improve that. We seem to be singing from the same hymnsheet, but different hymns that's all.
     
  14. mick's cat

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    Actually no, I take that back. I've re-read the paragraph. Lithium ion batteries *do* only last 2 or 3 years before the internal resistance builds up to the point that they cannot fully release their energy, whether you use them and keep them topped up daily, or use them only monthly. That may not be to the point they die, but it's certainly a gradual degradation, and it starts from the point at which they are made. My statement stands.
     
  15. mrtbag

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    Then give me some 'up-to date' figures that confirms this to be true on all Li-ion batteries!!

    You have a lot of good tips for helping people get the best out of their batteries. But some of the statements you make are 'fictitous'.

    Envocare did extensive research with many manufactures last year. 50% of Li-Ion batteries that will be manufactured in 2005 will be capable of an average 1000 cycles. So even at 1 charge per day, that is more than 3 years.
     
  16. Ekko Star

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    Yes bit perplexed by this, fact & fiction crossing wires I guess.

    Manufacturers tend to indicate average life cycles rather than years don't they? From the numbers being quoted here we are talking between 400~1000 life cycles. So surely when equating to average years the formula would remain a multiple of greater than 2. ie 1-2years, 2-4years ?

    That is further exacerbated by the fact some batteries hold a longer charge. Can be anything from 6hrs ~ 30hrs I'd guess ?

    Multiple of cycles and we are then talking greater than the years being quoted. So it is all rather misleading.

    Then again as we all know with batteries, they never last as long as they should anyway ! Add into that temperature variances and is the battery run flat out or in parts and it all becomes a bit confusing. Certainly not the exact science or clear cut fact it is being presented as.
     
  17. mick's cat

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    Assuming you meant 'fictitious' my first thought on reading this was to report you to an admin/moderator. However, I thought that doing so without warning you first was as lofty as you are being. So, remembering that it is you accusing me of lying, the onus is on you to prove it.

    Once again, I think you've missed the point, and I'm still sorry if I wasn't clear enough for you earlier on. Let me try to summarise this for you to understand. All lithium rechargeable batteries degrade from the instant the chemicals meet on the production line, so that their capacity to supply current becomes reduced with time. If, while you use a lithium battery in a DAP or laptop, or camera, or whatever, you don't keep it topped up, it degrades faster than if you do keep it topped up.

    Even if you don't use a battery it will degrade and, unless you take precautions, its capacity will reduce (for lithium-ion batteries, this natural degradation is approximately 20% a year - although this can be reduced to about 4% by discharging it to about 40% and storing it in a refrigerator). So as a result, if a lithium rechargeable battery is inside a DAP, laptop, camera, or whatever, and not used, it still degrades.

    The average life is irrelevant. It is just that, an average. Some will degrade to the point of not being useful before that time, some will reach that point after. This will depend to a major part, on usage. And by the way, 1000/365 = 2 years 9 months - within the 2 to 3 years I stated earlier.

    I really don't know what we are discussing here now or where the thread is going - you seem to be aggressively and without any basis challenging everything I say, and have hijacked the thread to the point of it being of little use to DAP users who've probably got bored and switched off. Are you saying lithium batteries don't degrade? Are you saying that you shouldn't keep them topped up in use? That you should run them till they are totally discharged before charging them?

    Please tell me what you don't understand and I will willingly try to simplify further for you.
     
  18. mick's cat

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    There is no fiction. I never said that it wasn't perplexing. I merely stated the facts of lithium battery life. You can take them (and improve your battery's lifespan) or leave them. Your choice.
     
  19. mrtbag

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    Err.... I don't actually think that dissagreeing with somebody is an offence on this forum. I disagree with some of the statistics you have come up with. As you seem to claim some of these as 'facts', then yes some of them are IMO 'fictitious'. Report away!!
     
  20. mick's cat

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    Ahh, but you weren't merely disagreeing. You called me a liar, by saying that what I have reported was fictitious. At least you now clarify your position by adding that it's only your opinion. Yet you persist in being unable to disprove anything, other than now saying you disagree with 'some of the statistics'. You haven't even been able to specify what you disagree with to give me the opportunity to reply.

    By all means, if you can bring something new to the discussion, then I would welcome it. But unless you can, you have merely obstructed the thread by confusing the issue, which is a pity for other users.
     
  21. mrtbag

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    Your statistics on battery life for Li-ion which you stated, and the site you linked to are old information. I'm mearly providing you with updated facts.

    Yes it's my opinion, and an opinion I gained through my job. I work for a consumer electronics manufacturer.
     
  22. Pecker

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    RE:

    "...there's no point in buying a spare battery now in case the one you use dies - they'll die together, regardless."

    Now that's highly improbable. If the average lifespan of a battery is 2-3 years, then you're the unluckiest person on earth if both your batteries die after (for example) exactly 2 years, 3 months, and 5 days.

    Granted, if you are buying a spare battery with the sole purpose of hiding it away in a desk drawer, for the sole reason that you'll get it out to replace the battery in your unit when it gives out, then you have a 50% chance of the replacement battery being dead when you try to replace the original.

    My whole point is that, with a unit where you can replace the battery yourself, you can keep BOTH batteries topped up. If you wish to only discharge the battery to 40% of the capacity, rather than a full discharge, then you're effectively shortening the running time of your battery by 40%. But if you have 2, then you're still going to double that time.

    Let's put it in practical terms.

    Tom has a unit with a replaceable battery, and he buys a spare. Dick has a unit where the battery is non-user replaceable. Both units have a battery length of 10 hours. Both Tom & Dick decide to only discharge their batteries to 40%.

    That means that Dick will only be able to use his unit for 6 hours. Meanwhile, Tom will be able to use his unit for 12 hours (6 hours per battery).

    The chances of both batteries finally dying during the same week are virtually zero. If you have 2 batteries, then one will almost ceetainly give before ther other. It doesn't matter if the one that gives first is the one that came in your unit or the spare. The fact remains that you can bin the one that dies first, and you'll still have one to run your unit on while you wait for the replacements you order.

    You don't have to send the entire unit back. You don't have to do without your music while you wait for the order to come through.

    In our scenario (above), at some point between 2 & 3 years (out of warrenty) Dick has to send his unit back to the manufacturer - at his own cost - and wait for it to come back. No music in the meantime. And the manufacturer will charge a lot of money to replace your battery.

    Meanwhile, one of Tom's batteries dies. He puts that battery in the bin and continues using the other. He orders a new battery, but still has his unit while the replacement arrives.

    Oh, and it'll be miles cheaper for Tom, too!

    Having a user-replaceable battery is cheaper and more convenient, whichever way you look at it. The exception to this rule is if you will never be away from a charging point in the time frame of 60% of the stated battery life, or more realistically 60% the battery life in real world conditions.

    Most people's experience appears to be that, in normal use, you get maybe two-thirds of the quoted time.

    Example:

    i-pod mini - Apple's quoted time 8 hours - likely time in 'real world' conditions c.5 & a half hours - 60% = c.3 hours

    So, in answer to the original question right at the start of the thread, 'How important is battery life', well that depends on how long you use the unit for.

    I'm usually 'on the road' for maybe 3 hours in a day - longer if I go to the supermarket on my way home. So, for me, if I had a unit with a quoted battery life per charge of 8 hours, and I wanted to keep the charge up to 40%, I'd be struggling. Worse if I want to spend more than 3 hours on the beach in the Summer. Worse ifI'm wanting to use the unit on a flight/train journey, etc.

    But I'm not everyone. If I lived 10 minutes walk from work (I wish), battery life would mean much at all.

    Thanks for the very informative link, BTW.

    Steve W
     
  23. Pecker

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    One more thing we haven't discussed.

    If your battery lasts 2-3 years, do you envisage having the same unit in 2 years time, or do you think you'll have replaced it?

    Different people, different answers, different level of importance on battery life.

    Steve W
     
  24. Cloysterpeteuk

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    I use an ipod 20GB 4G which I have had maybe 3 weeks and took the thing to work yesterday, thing ran out at around 5pm so I connected it to i-tunes and looked at how long I had been listening that day, the result : 5 1/2hrs!, bloody appaling (im doing a not touching test today). When the things has a stated life of 12hrs I would expect to get a least ten hours. My conditions of usage were shuffle, 192k files, volume adjust maybe 5 or six times, no menu flicking, no backlight and no eq.

    I don't believe that all LI-Ion batteries would die after two or so years, regardless of usage. I use ipodlounge who know everything about ipods and they have the following say this in there faqs:-


    ================================================================
    Q: What is the expected life span of iPod's battery? What are some battery recharging tips?


    A: The iPod's Sony Lithium polymer battery (model# UP325385 A4H in the June 2001 Catalog) is rated for more than 500 charging cycles - one charging cycle consisting of draining the battery, than recharging it to a full charge. Therefore, the life span you should expect from your iPod's battery will depend on how often you have to fully recharge the battery. Worse case, assuming consistent, very heavy daily use, you might need to fully recharge the battery every 1 or 2 days. This would result in an expected battery life span of 2 - 3 years. A lighter, probably more typical usage pattern might result in a full recharge once a week on average. This should equate to an expected battery life span of 9 - 10 years.

    Please bear in mind that these are estimates and are based on 500 recharge cycles - which is the minimum number of recharge cycles for which the battery is rated. Also, since the iPod has been around for less than a year, no one has any real world experience to back up these estimates.

    Finally, please remember it is recommended to never allow your iPod's battery to completely discharge since it is never turned totally off (it instead just sleeps - this is what provides iPod's instant on capability). You should recharge it to full charge regularly, before it has an opportunity to fully discharge (Lithium polymer batteries do not have a "memory"). In fact, some experienced iPod users try to never let their iPod's battery indicator get below 2 bars. Also, many experienced owners always recharge using the AC adapter as opposed to recharging from the FireWire port on their computers. In certain situations, the iPod's HDD will spin continually when connected to a computer, causing excess wear on the drive & power drain. This can be avoided if you "eject" iPod in iTunes and Finder, making the FireWire port a "charge only" port. Or, you can opt to always recharge your iPod using the AC adapter (or a car recharger).

    Find more information on the iPod battery at the iPod Battery FAQ.
    ================================================================

    So are you saying the bit about 9 years is BS?, because the site is the number one info source for ipod owners and a glaring error like that would soon be pointed out. I mean when they give you these battery they say it's 500 cycles, whether you use them up in one year or ten years, they don't say 'Oh it's 500 cycles but you have to use them all in a couple of years or the battery will fail!. I know my Li-Poly battery in my phone is still going fine after 3 years.
     
  25. MikeK

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    If you buy a Creative player (like I did), you may well have no choice!!
    I bought a Creative JB3 last April - the batteries are no longer available from Creative or anyone else it seems.

    Guess which maker will definitley NOT be on my list next time!
     
  26. Spacecowboy

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    Hold on a sec lads, my heads starting to spin :confused: :suicide:

    To sum up, if you have a Li Ion battery in your DAP (or your mobile for that matter):

    (1) Plug it into the mains, at every oppurtunity you get? OR wait till its down to 40% capacity and then charge back up to maximum?
    But either way wouldn't each recharge count as 1 cycle, and thus you will get to the avg. no. of maximum charge cylces quicker? I'm prob being stupid here!

    (2) After every 30 recharges (or approx. 1 per month), completely discharge and recharge to maximum. Correct?

    (3) And if i aint using it for a month or 2, leave at 40% capacity in a cool place, like a fridge. (tho i'm not too confident about sticking my DAP in a fridge!)

    OK back to the real world, I've just bought a a Sony HD3, and i'm not hitting anywhere near 20-30hrs. After a full charge, I listened for 8hrs 50 mins and the battery gauge is showing 25% capacity left!!
    I'd guess of the music i was listening to; 60% was atrac3+ 64kps and 40% was mp3 128-192kps.

    Thing is i bought it off ebay, and i'm thinking i've maybe bought a shagged out player! :mad: But then again its not been out long, so how could the battery be worn out? and its still gotta be under warranty.
    The troubleshooter in the manual, offers this answer "You have not used the player for a prolonged period. Efficiency of the battery will be improved by repeatedly charging and discharging" :lease:
     
  27. mick's cat

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    The iPodlounge forum is correct in saying that the best way to keep lithium ion batteries in best shape for longest is to keep them topped up regularly. This is to do with the number of cycles a lithium battery has in its lifetime, and also to do with the fact that deep-discharging a lithium ion battery is bad for it. So, using it till it is down to a 50% charge, say, then recharging it back to 100% before you use it again down to a 50% charge then recharging it again (2 x 50% = a full cycle), is much better than simply using it till it it is fully discharged before recharging it.

    However, I the forum appears to have forgotten the effects of degradation (sometimes called aging) - which is a loss of a lithium battery's capacity to deliver its charge - and which occurs from the moment of manufacture regardless of the number of cycles the battery undergoes. Degradation cannot be stopped, and it has to be added into the equation. Lithium ion battery degradation is approximately 20% a year - about one fifth. So if we start with a perfect 100% battery at time 0, then we can expect a battery to degrade fully in about 5 years under laboratory conditions.

    Out of the laboratory and in the real world, things are rarely that good though. A lithium battery effectively stops working before total degradation. As far as the user is concerned, this seems to happen suddenly, but in fact it has been a culmination over a long period of time. What happens internally to the battery as it degrades is an increase of internal resistance which makes it harder for the battery to deliver the stored energy inside. When the internal resistance increases to the extent that the battery cannot deliver sufficient of its charge to power the device it's powering for more than a few minutes, that's when - as far as the user is concerned - the battery appears to have died. It still has a charge, but is simply cannot deliver it. The particular point when this occurs depends on the device's power requirements, the individual battery, and the user's perception of what the battery should be able to do, of course, but at a guess we can probably place it at around 20% or so of the battery's full capacity.

    Degradation happens regardless, yet varies depending on other factors. It happens whether the battery is charged frequently or not. It occurs even if the battery is unused. It is increased if the battery is deep-cycled. It increases if the ambient temperature of the battery increases. Any figures quoted anywhere, by any manufacturer, are - because of these factors - all approximates, and that's why it's impossible to define the exact lifespan of a lithium ion battery. While they might say 500 or 1000 or whatever cycles, they can't guarantee that because it all depends on usage.

    Having said all that, if you are only getting 5 and a half hours from a 4G iPod battery then it is not good. Before you go to Apple though check a few things. I've heard that restoring an iPod sometimes helps with battery life. This could be something to do with hard disk fragmentation. Check these sites too for useful ipod battery information:

    http://www.vsa.cape.com/~danh/ipod.htm

    http://ipodbatteryfaq.com/

    Best of luck.
     
  28. mick's cat

    mick's cat
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    A cycle is additive. So when it's down to 80% charge, you recharge it then use it to 80% again, then recharge it, you've gone through only 40% of a cycle.

    If it has a battery gauge, yes. This re-calibrates the gauge to make it more accurate.

    Yes. Definitely not in the freezer though, as temperatures below 0 degrees will damage the battery (and the rest maybe...)

    This is probably to do with point (2) rather than a duff battery. The last 25% on the battery gauge will probably last you another 20 hours...

    The manual is correct and reflects what I've been saying throughout the thread.

    Keep us posted with your results.
     
  29. mick's cat

    mick's cat
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    Yes, that's correct of course. They will not both die at *exactly* the same time. As any lithium battery (or any other form of battery) lifetime has so many variables, there will be a gap between two batteries dying.

    Yes, you're right, that's true too. Overall running time is improved by having more than one battery.

    But lifetime won't be improved, and possibly reduced slightly because when you're using one battery the other isn't being used. Unless a battery is in refrigerated storage, using it and keeping it topped up is the best way to get maximum lifetime.

    And, as you say, when a battery dies, will anyone buy a new battery, or a new DAP? The way the market is going, with new features being added rapidly, I suspect nearly everybody's answer to the question is to buy a new DAP. I know the answer to that in my case already, and my battery's still perfectly fine... :thumbsup:
     
  30. Spacecowboy

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    Ok following on from this the battery had 25% capacity left and i got another 10hrs 30 mins out of it, heres how i listened to it:

    9.5hrs = atrac3+ tracks at 64kps, (Vol. 30-40%)
    1hr = mp3 tracks at 128-256kps, (Vol. 50%, maybe 60% max)

    Still not too impressed with the battery life, god only knows whats gonna happen when i take the volume limiter off!

    For the next 1-2 wks i'm gonna recharge every time the battery drops to approx 50%, and see if that makes any difference to the total battery life. Because up until reading this thread i was under the impression, that to prolong battery life you were meant to run the battrey dry and then do a full recharge from 0%. :oops: Hey i'd read it somewhere on the net recently! prob some other pesky forum.
     

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