Quote:
Originally Posted by obsessed2
I'm an electronics technician. It's my understanding that each cell in a lithium battery has to charge to 4.2 VDC and then the charger gradually reduces the charge current until it has dropped to a small percentage of the initial charge rate, at which point the battery is considered 100% charged. For most lithium batteries this is typically 2% to 3% although it can be a little more as in the case of my Viewsonic gTab which tops out at 96%, but not the 10% to 20% you and elcreative are suggesting. If this were the case every device would be DOA with 10-20% battery remaining. I typically recharge my tablets at 25% but they have dropped as low as 10-15% on occasion without completely dying.
Dr. Soneira says that there is something wrong with the battery charge mathematical model on the iPad. He's saying that the user will not get the maximum running time that the iPad is capable of delivering. Dr. Soneira obtained his Ph.D. in Theoretical Physics from Princeton University, so I think he is more qualified than you or I or most other members of this forum to speak in this regard.
It's almost my understanding that lithium batteries are smart batteries with a cutoff potential of 4.3VDC to prevent cell damage. Obviously the Apple spokesman doesn't know what he is talking about. I'm sure he's taking the proverbial butt-chewing as we speak.
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[moderation edit] I only went by the spec details from various manufacturers and the way they say Lithium polymer cells work but a Ph D in Theoretical Physics obviously trumps the actual specs (do a search for 'em yourself) and even the article has connections to other posts casting doubt on the claim/way the claim is put forward...
[moderation edit]
Also these batteries don't overcharge by being left on charge, they have circuitry to prevent that... and it works very well if not mistreated... it also seems that we were discussing the top end of the charging displays not the bottom and, again if you read the manufacturers' data, the batteries shouldn't drop to zero (causes irreversible crystallization of the cells) so the display doesn't actually mean zero when it says that, it means within safe minimum before closedown until recharge... [moderation edit]
Edit:
This comment now not accurate due to over eager mod editing... I do not support this statement and wish it to be deleted from this thread along with my other comments and references...