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Subject: Re[2]: heating
From: Uwe Freese (
Date: 2002-12-19

Hello Doug,

Doug wrote on Thursday, December 19, 2002, 4:38:07 AM:

D> - If the batteries are full, the charging current cannot charge the battery
D> anymore. So the energy is absorbed by heating up the battery.
D> - Each battery has a negative temperature coefficient, that means the voltage
D> goes down when the temperature goes up.
D> -----------------
D> As you can imagine, I'm not much of an expert on the charging algorithm,
D> however I have an aching suspicion that this--barring any defect in my
D> unit--was cause for the shutdown.

D> Tell me if you think the properties of the batteries or the algorithm itself
D> could have caused the batteries to drain because of the heat.

The voltage goes down only some mV when the batteries get hot, not down
under shutoff-voltage (it is about 1 V between max. and min. voltage). I
don't think it's possible that the heat tricked the charging algo.

Because the shutdown happened while deep discharge was off, I really
think that something must be wrong with your unit. But I don't know,

Bye, Uwe.

Page was last modified "Jan 10 2012" The Rockbox Crew