On Tue, 6 Oct 2015 16:34:07 +0200 Pavel Machek <pavel@xxxxxx> wrote: > 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 > 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. Regards, Andreas Kemnade
Attachment:
signature.asc
Description: PGP signature
