Re: Charging my iPod

["Tom Metro-12" <user=71@nabble.blu.org>]

 Jon Hermansen wrote: 
> Since I've just installed this battery, I want to make sure that I charge it 
> correctly and fully the first few times, i.e. not "trickle" charging it. The 
> instructions that came with the battery specifically indicate that I should 
> NOT charge it over something like USB (or FireWire?) 

Doesn't the iPod use a lithium polymer battery[1]? 

According to: 
http://www.batteryuniversity.com/partone-12.htm

   Lithium-ion...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. 

Do the instructions say don't use USB in general, or specifically for 
the first few charge cycles? 

1. http://en.wikipedia.org/wiki/Lithium-ion_polymer_battery


> GRIFFIN AC POWER SUPPLY 
> OUTPUT: 5.0V   500mA 
> 
> Can anyone tell me if this is a more high powered charger, or if I use it 
> will the results be the same as if I charged it over USB? 

If I remember correctly, USB supports both high and low current devices, 
with the high current being supplied by PCs and powered hubs. I believe 
that the high current limit is 500 mA. So this charger matches that. 

The warning might be because it's simpler to say don't use USB than 
trying an explain that it needs to be a port supporting high current 
devices. Or, if the iPod has a separate charger jack, perhaps it does 
support charging at higher currents. 

If it was a NiCd battery, 500 mA would be pretty decent, as you 
typically charge at .1C where C is the batteries capacity (that's the 
slow, "overnight" rate, but usually faster than the "trickle" rate). So 
that'd be a 5000 mA/hour or 5 Ah battery pack, which I'd guess is bigger 
than what the iPod uses. Though a quick charger or one designed for NiMH 
will use a faster rate. 

The above page also said: 
   Smaller batteries used for cell phones can be charged at 1C... 

and if that's applicable here, the 500 mA supply probably is too small. 
But the page also says: 

  Increasing the charge current does not shorten the charge time by much. 

Without knowing the battery chemistry and capacity, it's hard to say 
whether the power supply is adequate for a first charge. 

  -Tom 

-- 
Tom Metro 
Venture Logic, Newton, MA, USA 
"Enterprise solutions through open source." 
Professional Profile: http://tmetro.venturelogic.com/

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