Does anyone know how long a lithium polymer battery will last?

I am considering purchasing the new iAUDIO U2, which uses this kind of battery. It can apparently last up to 20 hours on every recharge, but it doesn't say how long the battery will last before it becomes un-rechargable.

Also, is this a battery type you can be able to replace yourself, or do you basically have to throw away the mp3 unit once the battery is dead?

Any answers much appreciated!

iRiver states the batteries they use (Li Polymer) will recharge to at least 80% rated capcity after 300 charges.
People *have* changed batteries in iRivers....don't know how hard it would be for IAudio.

great source for battery info:
http://www.batteryuniversity.com/

Bob

Thanks!

I couldn't find any too useful information on the site though, regarding the life expectency of these batteries.

I don't know what's the difference between regular lithium and lithium polymer batteries but I do know that regular lithium batteries don't last very long. The lithium battery that came with my Nikon Coolpix 995 refused to recharge after 3 years...I recharged it only about 50 times over its life. I thought this was a defect but my online research indicates this is unfortunately typical for lithium batteries.

This behavior is the biggest reason why I didn't buy the Dell MP3 jukebox (which is only $237 for the 20GB version)...it has a FIXED lithium battery. In several years it's going to be a nice paperweight.

>I don't know what's the difference between regular lithium and lithium >polymer batteries but I do know that regular lithium batteries don't last very >long.

I do know at least one of the différence between Lithion and Lithium Polyme cells:
the last one (LiPol) are more stable unlike Lithium only ones...

About autonomy I heard some echoes (saying that LiPo will last more than only Lithion cells) but nothing that seem very doubtless...

About changing the battery it depend if the connector is just plugged (as iHP or iFP5xx/9xx one) or soldered...

My 2 cents (or maybe less)

I think it depends how deeply you cycle them. With other rechargeables, lead-acid,ni-cad or nimh, full cycles rapidly wreck the capacity of the battery.

Nimh are particularly sensitive to overcharging or heat.

Smart chargers also extend battery life.

All I have been able to find on lithium batteries so far though is that they are the best in the cold.

I will post a more useful link if I can find one.

From define:lithium polymer
also for additional info define:lithium-ion.

IIRC, my brother had a Li-polymer celled battery in his Nokia mobile phone. Or maybe it was Ericsson.

tec

So no one knows, roughly, how long the battery in the iAUDIO U2 unit will last before it becomes unusable? Nor if this is something you'd be able to replace on your own?

I do know that there are several things which factor in though, including hours of usage, whether it's used/stored in cold or warm conditions, whether it's fully or partially recharged, etc.

It'd just be annoying shelling out $200 for a unit which will be unusable in less than two years -- and this unit wouldn't even be heavy enough to use as a paper weight!

If it has low life expectency I definitely won't go for the 1 GB model either...

Here a few facts from working with and designing around this technology for a few years:

1. Li-Ion batteries typically last between 300-500 cycles before serious loss in energy density, depending on quality and usage. Lithium Polymer batteries) the flat type found in most HD players) will last about 60%-80% as many cycles. My prismatic Li-ion cell phone battery has roughly 600 charge cycles on it, and has about 50% of original capacity after a charge.

2. Most of the time, they will have a better life (in cycles) if used at low discharge rates (ie. less than 0.5C). This is well within the specs of most players for an 800maH polymer cell and a flash or HD based unit.

3. Li-Ion batteries will last longer per charge when discharged at higher temperatures (they like hot weather). They perform poorly below freezing, and should never be charged below 0 Celcius. They will, however, last more cycles if stored at lower temperatures (ie. 15 Celcius...a cool basement). Same for polymer cells.

4. Cells are best charged using a CC-CV (constant current-constant voltage) type charger. Constant current until the battery reaches maximum 4.2V typical, then constant voltage under reducing current until the battery can maintain 4.2V at 50mA or less (end-of-charge current). Timed chargers wil result in lower life.

5. Bare Li-Ion cells are not available over the counter to consumers - the batteries have a high energy density and are extremely dangerous when shorted or punctured. These batteries are always (by law) designed into consumer electronics with a protection circuit (usually a FET with some additional comparator logic) to protect from overvoltage, undervoltage, and overcurrent conditions. Packs sold for cellphones, etc, have an integrated protection circuit attached to the cell within the pack.

Hope that answered your question(s)...

Edit: 6. Practically no memory effect - if you're in a hurry and the battery isn't fullly charged, no harm done.

They are generally gone in a couple of years. The big advantage of lith polymer vs lithium ion
is the polymer battery can be made thinner and/or custom shapes to fit the space available. Of course, if it is a custom battery, you have no choice but to get your replacement from Iaudio.

How does this model compare to Iriver's models that take a single AAA cell? (or was that AA)

Another disadvantage of Lithium vs a standard NiMH is that they take a few hours to charge (8 hours in my player), depending on the circuitry built into your player. You can get NiMh with a smart charger that will charge up in as little as 15 minutes.

Well, in thos post I am referring to the iAUDIO U2 unit, which is made by Cowon. The iAUDIO 4 uses normal AAA batteries, but I found the up-to-nine-hours playtime a bit discouraging, whereas the U2 has up-to-twenty. Plus, iAUDIO 4 doesn't support OGG and will only let you record at 128 Kbps using the internal microphone or the line-in. While the U2 does have both of these restrictions, the company has apparently promised to release firmware which will make it OGG-compatible and allow it to recored at higher Kbps -- upgrades which seemingly won't be available to their other Flash units.



So charging a lithium polymer battery will take several hours? Is there any difference between charging it through USB, or directly through a power socket?

I found this page that says there are 2 modes of charging taking 2 or 6 hours.. maybe the 6 is USB?
I know the power available through a USB port is pretty limited.

another listing

Charge time is a function of two variables:

1. Charge current.
2. Total cell capacity.

So charge time will vary based on the particular charger implemented and the battery being charged. USB chargers have strict current limits to deal with, so don't expect fast charge times for a high energy density cell like a Li-Ion battery.

I can charge the same 1850maH cell in 2 hours or 12 hours - the time required to achieve full charge is simply a function of charge current.

A wallwart will no doubt charge at a faster rate than a USB charger...

http://www.apple.com/batteries/

is a bit of info Apple provide about their batteries, there are links for ipod or powerbook specific info,

Kristian

If i connected the mp3 HD with lithium polymer battery to the ac adapter and it started charging, and the battery had not run down, would this effect the performance of the battery?

Yes, it will probably last longer. See the link in the post above yours.