Have a look at http://batteryuniversity.com/index.php/learn/ Bit of a rabbit hole though! RP On 31 May 2018 at 07:02, Van Horn, David < david.vanhorn@backcountryaccess.com> wrote: > The best sources I know of are the McGraw Hill handbook of batteries > (overkill but good reference) and the info online at Battery University. > > -----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 threshol= d? > The voltage during charge is higher than the cell voltage and will vary b= y > temp. How is the 4V determined... by temporarily disconnecting and cooli= ng > it off? Or is there some mapping/compensation to correlate the 4V at a > higher 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 > > charging and runs the battery down. It will only recharge if the > > charger is disconnected and then reconnected again. I wanted to use > > it as a webcam but..... > > > > For best battery life it should be charged to about 4V/cell. This > > 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 > > 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 > >> firmware control. > >> > >> Measure current over time on the DC input to document behaviour. > >> > >> Some phones reach charged state and disconnect the DC input, then > >> draw almost no current until either battery voltage falls, or > >> estimated state of charge falls below something like 90% or 95%, then > >> they reconnect until charged. > >> > >> Some phones reach charged state and disconnect the battery, operating > >> from the DC input until the DC input is removed. Of these, some > >> won't track estimated state of charge during the self-discharge > >> phase, and some will. > >> > >> One device I have goes one step further; if you leave it connected > >> for a week, it presumes you plan to leave it connected forever, and > >> says so; it disconnects the DC input until estimated state of charge > >> reaches 50%, then transfers the load to the DC input. > >> > >> Thus it entirely defeats the idea of keeping the device _ready_ for > >> use on battery in this way. > >> > >> -- > >> James Cameron > >> http://quozl.netrek.org/ > >> -- > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > >> View/change your membership options at > >> http://mailman.mit.edu/mailman/listinfo/piclist > >> > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at http://mailman.mit.edu/ > mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=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 .