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User Info Apple, The BeeEss Company; entered at 2017-12-30 22:49:39
Tickerguy
Posts: 151171
Registered: 2007-06-26
The problem is that one of the most-common failure modes on Lithium cells is that they go high-resistance under load. So you'll show "50%" (which is really just a VOLTAGE measurement that is allegedly proportional to the charge level -- and is, if the battery is in good condition), turn on the GPS, and wham -- the phone shuts off as the battery cannot provide the extra 250ma required to drive the GPS. The voltage sags, gets down to the 3.0v cut-off, and the controller in the phone kills the power (to prevent deep-discharging from destroying the battery.) Apple lied about THAT too -- they claim it's to protect the "sensitive circuits" in the phone. Horse****. The shutdown is to prevent the battery from being deep-discharged, which can cause it to SHORT internally -- and then CATCH ON FIRE when recharged at high rate because that nice short means instead of charging it just makes heat, and LOTS of it!

The proper thing to do if that happens, of course, is to tell the user that the battery is defective and requires replacement. What APPLE did was to instead throttle the CPU to try to cover up the fact that the cell was defective. This won't work for very long (maybe another couple of months) because the battery will not magically get "better".

The other fact is that the charge controller, if its paying attention, can detect this condition and alert the user before they start getting in trouble with unsolicited shutdowns because the rate of charge (milliamps drawn at a given voltage state of charge) starts declining -- by quite a bit. Resistance is two-way, you see. If a cell in good condition can sink 3,000mah when it's at a 30% charge state and it now only sinks 2,000mah or 1,500mah, well.....

Last modified: 2017-12-30 22:51:19 by tickerguy

2017-12-30 22:49:39