Hi! > > > Pavel Machek <pavel@xxxxxx> writes: > > > > On Thu 2015-07-30 10:11:24, NeilBrown wrote: > > > >> > > > >> Add a 'continuous' option for usb charging which enables > > > >> the "linear" charging mode of the twl4030. > > > >> > > > >> Linear charging does a good job with not-so-reliable power sources. > > > >> Auto mode does not work well as it switches off when voltage drops > > > >> momentarily. Care must be taken not to over-charge. > > > > > > > > Can you explain how the user can "care not to over-charge"? > > > > > > The following text reads: > > > > > > It was used with a bike hub dynamo since a year or so. In that case > > > there are automatically charging stops when the cyclist needs a break. > > > > > > so: take a break from cycling occasionally. > > > > If the charger does not exceed 4.2V, I'd not call it overcharge. (Yes, some clever > > chargers actually let the battery drop below 4.2V when charge is done, but...) > > > Yes, that is the case. Perhaps it is not to be called overcharge but > it is said that lithium battery charging has to stop if in CV mode the > current drops too low. In automatic mode the charger does exactly > that. > I would not let a battery for days at 4.2V CV.mode although a lot > of cheap chargers Well, I agree that keeping battery at 4.2V constant voltage mode is bad, but I'd not call it overcharge. If someone can fix the comment, that would be nice. > > If the charger _does_ exceed 4.2V, then the battery will explode. Don't do that. Don't > > offer that to the user. > > > > On a related note... I've just killed USB charger by overloading it. They are not protected. > > > > I believe your automatically-pull-max-power really should stick to the well-known charging > > currents (.5A, 1A, 1.7A), at the very minimum. > > > The main reason for the patch was to prevent switching off charging > when Vbus drops low. The reason was not to get out extremely much > current out of the charger. > The electrical characteristics of a bicycle as a power source are. > - the amount of current available changes > - 500mA at around 17km/h > - you cannot destroy it by electrically overloading > > If the current is set to e.g. 500mA and that linear charging mode is > enabled, the battery gets the maximum current available (upto > 500mA) regardless of the speed which is often changing. Yes... I guess that makes sense for you, but I wonder if we should be doing this by default. It seems a lot of cheap chargers can be easily destroyed if you overload them. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
