When I was designing NIMH chargers on the AVR, this was one of my go-to sou= rces. Tempered by the data sheet of the specific cells we were using. NIMH is a real pain to charge correctly especially if your charger has to o= perate in other than shirtsleeve temperatures. -----Original Message----- From: piclist-bounces@mit.edu On Behalf Of Richar= d Prosser Sent: Wednesday, May 30, 2018 2:20 PM To: Microcontroller discussion list - Public. Subject: Re: [EE] LiOn battery stress / Trickle charge a smartphone? 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=20 > (overkill but good reference) and the info online at Battery University. > > -----Original Message----- > From: piclist-bounces@mit.edu On Behalf Of=20 > 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=20 > vary by temp. How is the 4V determined... by temporarily=20 > disconnecting and cooling it off? Or is there some=20 > 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=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=20 > > 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=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%,=20 > >> then they reconnect until charged. > >> > >> Some phones reach charged state and disconnect the battery,=20 > >> operating from the DC input until the DC input is removed. Of=20 > >> these, some won't track estimated state of charge during the=20 > >> self-discharge 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=20 > >> charge 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=20 > View/change your membership options at http://mailman.mit.edu/=20 > mailman/listinfo/piclist > > -- > 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 .