Re: Charging voltage for droid4 battery

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Hi!

> * Pavel Machek <pavel@xxxxxx> [190819 12:44]:
> > Hmm. Related changes make it harder, not easier but.. here you
> > go... But... while this is simple... you are applying it at your own
> > risk. Untested. One potential problem is that while mainline will charge
> > to 4.2V, "power off charging" and Adroid will still charge to 4.35V,
> > leading to charge/discharge cycles even while charging is connected.
> 
> I guess not much we can do about Android charging at 4.35V.

Well, true. 

> > > Then later on we may want to optionally consider implementing
> > > support for 4.35V charge voltages assuming we scale down the
> > > charge voltage to 4.2V after reaching full charge.
> > 
> > Not sure how that would work / why we'd want to do that / what do you
> > consider to be full charge.
> 
> Well that would be if we wanted to make use of the extra capacity..
> 
> > https://secondlifestorage.com/t-Li-ion-4-35V-How-much-do-we-lose-by-charging-it-at-4-20V
> > https://batteryuniversity.com/learn/article/confusion_with_voltages
> 
> .. but yeah I don't know what we should consider full. I guess it's
> a 3.8V/4.35V battery vs 3.7V/4.2V battery.. To me it seems safest
> to set charge voltage to 4.2V and battery full to 4.2V until we
> we have some better ideas.

Well, feel free to apply the one-liner. Plus you can have a full patch
to make current and voltage configurable...

> > +++ b/drivers/power/supply/cpcap-charger.c
> > @@ -440,7 +440,7 @@ static void cpcap_usb_detect(struct work_struct *work)
> >  			max_current = CPCAP_REG_CRM_ICHRG_0A532;
> >  
> >  		error = cpcap_charger_set_state(ddata,
> > -						CPCAP_REG_CRM_VCHRG_4V35,
> > +						CPCAP_REG_CRM_VCHRG_4V20,
> >  						max_current, 0);
> >  		if (error)
> >  			goto out_err;
> > 
> 
> So I think you also need to change the battery full to 4.2V too? Sure
> if Android charged to 4.35V, we show 15 minutes of over 100%..

Umm. I am not sure I need to change anything else _in the kernel_?

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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