Do I really need to fully charge my new Ipod battery?

October 26, 2006 4:45 PM

I just got a new battery in my ipod. The instructions say I need to charge it for a few hours before using. Is there any reason for me not to unplug it before it fully charges and start using it?
posted by ManInSuit to technology (19 comments total)

Well, yes. They say that for a reason. I think if you do that you run the risk of damaging the battery and eventually getting less playtime out of it.
posted by ORthey at 4:46 PM on October 26, 2006

If it doesn't charge to 100% the first time, it might not "learn" its full charge capacity.
posted by phatkitten at 4:48 PM on October 26, 2006

I don't buy either of those answers. I did not fully charge my iPod before I started using it. I've never noticed a problem, but then I didn't do a side by side comparison with one that was fully charged.
posted by Science! at 5:04 PM on October 26, 2006

I don't know what the answer is, but I don't buy the first 2 answers, at least until I hear a sound explanation. Any EEs out there? The answer may be less technical than it is legal (ie liability issues), such that the warning is a CYA sort of thing.
posted by allelopath at 5:10 PM on October 26, 2006

Yeah. I surfed around before posting the q.

Found lots of sources saying "It'll hurt the battery". Also found lots of sources (albeit fewer) saying "no it won't". But I couldn't find anything definitive either way...
posted by ManInSuit at 5:16 PM on October 26, 2006

phatkitten's expanation is expressed in vague, non-technical terms that might not inspire confidence, but I think he/she is right. To my best memory every device I've come across with Li-ion batteries says that they must be charged to full capacity on first use.
posted by randomstriker at 5:22 PM on October 26, 2006

I'm pretty sure that not charging it all the way up the first time makes the battery meter freak out.

This happens sometimes anyways. You can fix it by running the charge down until the device turns off, then charging it all the way back up.

At least in my experience.
posted by joegester at 5:25 PM on October 26, 2006

Lithium-ion is a very clean system and does not need priming as nickel-based batteries do. The 1st charge is no different to the 5th or the 50th charge. Stickers instructing to charge the battery for 8 hours or more for the first time may be a leftover from the nickel battery days.

Unlike nickel and lead-based batteries, a new lithium-ion pack does not need cycling through charging and discharging. Priming will make little difference because the maximum capacity of lithium-ion is available right from the beginning. Neither does a full discharge improve the capacity of a faded pack. However, a full discharge/charge will reset the digital circuit of a 'smart' battery to improve the state-of-charge estimation
posted by Science! at 5:26 PM on October 26, 2006

You are looking in the wrong direction here, Science. The first-time charge-up is likely for the protection circuit, not the battery itself. Case in point:

Last time I bought a third-party battery for a laptop, I let it discharge all the way to see what would happen. The laptop's battery meter hit 00:00 left . . . and thirty minutes later, the battery gave out. A full charge cycle after that, and the laptop never gave an inaccurate reading.

The lithium-ion cell packs don't care about memory issues, but remember that li-ion packs are stored around 40% charge. They've never been full-cycled in a product before hitting the retail shelf.
posted by Mikey-San at 5:34 PM on October 26, 2006

(Stored long-term in factories or product warehouses, that is, where "long-term" is two weeks or more.)
posted by Mikey-San at 5:35 PM on October 26, 2006

I second the call for an EE to clear all this up. I think most of the opinions out there are caused by people not really paying attention, or having no desire to, and a surprising lack of hard evidence about this.

C'mon internets! Feed us the true story through your many tubes.
posted by Science! at 5:40 PM on October 26, 2006

In the time it will take you to wade through all the responses here (or on the other sources you say you checked), the battery will be fully charged per the manufacturers recommendations. Fulling charging the battery will do you no harm. Not full charging the battery could potentially undermine the effectiveness of the battery. Why not simply charge the battery completely and be done with it?
posted by terrapin at 5:43 PM on October 26, 2006

The main reason to do a full charge is to calibrate the battery gas gauge. Partial charges are just fine for lithium ion batteries. They don't have any "memory" problems like NiCads. But after a few dozen partial charges, you need to do a full charge again to recalibrate the gauge. If the gas gauge is not properly calibrated, it may cut off operation prematurely.
posted by JackFlash at 5:44 PM on October 26, 2006

Almost all historical rechargeable battery issues is due to 'dumb' chargers which overcharge cells, and hence overheat them. Overheating is bad for the chemistry.

I take terrapin's point, 'why not just do it'. No offense intended, but I kind of despise that lack of curiosity, and the unquestioning obedience..

I've no experience with lithium ion batteries, but JackFlash's point seems quite sensible.

I second the call for an EE to clear all this up.

Trust me, you need much more than just an EE. Also, you might actually be looking for a highly specialized chemical engineer, rather than electrical. Even then, there is so much misinformation out there about batteries and charging..


Unlike nickel and lead-based batteries,

Memory effect is a myth. You probably haven't ever owned a battery that exhibited memory effect.


Good links about batteries would be very much appreciated, especially something like a thorough summary aimed at academics and professionals.
posted by Chuckles at 7:41 PM on October 26, 2006

The wikipedia article I linked points to the battery information part of the sci.electronics.repair FAQ. On a quick glance, it looks good for general urban legend debunking and basic practical advice.

That entire FAQ is very interesting reading, actually.
posted by Chuckles at 7:48 PM on October 26, 2006

Reading further down.. Looks like lots of higher end details about batteries too.

Good stuff, that FAQ.
posted by Chuckles at 7:52 PM on October 26, 2006

Okay, just one more, for now..
Unfortunately, a bit dated:

[Document Version: 1.07] [Last Updated: 5/95]

You can't have everything..
posted by Chuckles at 7:55 PM on October 26, 2006

Not an EE, not a chemical engineer, but 10 years day to day working technical experience with rechargeable cells of all types has given me a good knowledge of them - and a healthy respect for the Li-ion & Li-pol types.

With any of the Li-based cells, the initial charge instructions are more to do with starting off in a known state than anything else. Li-ion & Li-pol cells don't really show many of the self-limiting charge or discharge characteristics that Pb, Nicad, or NiMh cells do, while at the same time having much more extreme consequences to overcharging and over-flattening. Since they don't show obvious charge / discharge endpoint indications, the charge monitors work mainly on time, current in/out, and temperature.

Except in certain specialised applications, rechargeable Li-based batteries are required by law in most countries to have a built-in charge monitor/controller to prevent these consequences. Hence it's a good idea to, whenever possible, fully charge and discharge the battery each time.

The little buggers are effectively liquid metal fire under pressure, and it's not a good idea to let it out. YouTube is a good source for videos of the consequences.
posted by Pinback at 10:21 PM on October 26, 2006

I don't believe that the OP's question is about intellectual or academic curiosity, nor that my original answer equals the "unquestioning obedience" that Mr. Chuckles so despises.

I found Apple's ipod battery FAQ, and one of the answers indicates that one does not have to "prime" the battery for 24 hours. Only until the battery full indicator displays. The FAQ also addresses the "memory effect" concern as well as whether one should drain the battery completely between uses or recharge it whenever it is convenient.

What ManInSuit does with this information is up to him. Good luck.
posted by terrapin at 6:17 AM on October 27, 2006