At half power what should I expect to read for Battery voltage?

I am trying to diagnose a iPod battery charge issue.

I assume full charge is maintained at 3.5 volts via the white sensing wire on the battery.

If my iPod graphic battery indicator says 1/2 charged, would I expect the battery voltage across the black and red terminals to be around two volts?

And does anyone know what voltage I should see across the black and red terminal of the battery while on charge? I am seeing 3.5 volts but would think it would have to be 4 volts or so to charge it up to 3.5 volts.

Any technical help would be appreciated.

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3.5V is a very low voltage -- that's the minimum cutoff for the "low battery warning"; any lower than that and the device won't even boot (it'll just show the red empty battery symbol while it charges above 3.5V).

Charging voltage between red and black should be 4.1-4.2 volts. The white wire is not a reference voltage -- it's connected to a thermistor that cuts off charging if the battery overheats. If it's not connected properly, then the battery won't charge; I suspect that's what's happening.

(I can't give you a voltage that means "50% charge" -- LiPoly/LiIon batteries measure around 3.7V for most of their normal service range. Check out how flat the green line is on the first chart at http://www.mpoweruk.com/performance.htm !)

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Agree with bushing on that one. The Voltage will remains constant, it is the amperage that changes. Even a battery that is 99% depleted will show that voltage.

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Voltage stays the same, any lower or is will not boot or too high and battery will probably not work

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