The best sources I know of are the McGraw Hill handbook of batteries (overk= ill but good reference) and the info online at Battery University.=20 -----Original Message----- From: piclist-bounces@mit.edu On Behalf Of Neil Sent: Wednesday, May 30, 2018 11:32 AM To: piclist@mit.edu Subject: Re: [EE] LiOn battery stress / Trickle charge a smartphone? I recently started looking at LiPo charger ICs for a project. Do you have any links to whitepapers etc on this 4V/70% charging threshold? The voltage during charge is higher than the cell voltage and will vary by = temp. How is the 4V determined... by temporarily disconnecting and cooling= it off? Or is there some mapping/compensation to correlate the 4V at a hi= gher temp? Cheers, -Neil. On 5/29/2018 6:09 PM, Richard Prosser wrote: > An I have another phone with an annoying "feature". > If left on the charger it fully charges the battery, then stops=20 > charging and runs the battery down. It will only recharge if the=20 > charger is disconnected and then reconnected again. I wanted to use=20 > it as a webcam but..... > > For best battery life it should be charged to about 4V/cell. This=20 > corresponds to about 70% charge. Above this voltage the anode degrades. > Below this voltage and the cathode degrades (so I'm told). > If you have control of the inner workings of the charger you could try=20 > resetting the voltage to ~4V/cell (4V ?) and just leave it plugged in. > > RP > > > > On 30 May 2018 at 09:08, James Cameron wrote: > >> In my experience it depends on the phone DC input, usually under=20 >> firmware control. >> >> Measure current over time on the DC input to document behaviour. >> >> Some phones reach charged state and disconnect the DC input, then=20 >> draw almost no current until either battery voltage falls, or=20 >> estimated state of charge falls below something like 90% or 95%, then=20 >> they reconnect until charged. >> >> Some phones reach charged state and disconnect the battery, operating=20 >> from the DC input until the DC input is removed. Of these, some=20 >> won't track estimated state of charge during the self-discharge=20 >> phase, and some will. >> >> One device I have goes one step further; if you leave it connected=20 >> for a week, it presumes you plan to leave it connected forever, and=20 >> says so; it disconnects the DC input until estimated state of charge=20 >> reaches 50%, then transfers the load to the DC input. >> >> Thus it entirely defeats the idea of keeping the device _ready_ for=20 >> use on battery in this way. >> >> -- >> James Cameron >> http://quozl.netrek.org/ >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 >> View/change your membership options at=20 >> http://mailman.mit.edu/mailman/listinfo/piclist >> -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .