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Subject: Re: Battery Questions not in FAQ
From: [IDC]Dragon (idc-dragon_at_gmx.de)
Date: 2003-12-19


> [IDC]Dragon wrote:
> > Yes, Rockbox is started and it's (admittedly buggy) charging algorithm
> and
> > screen takes over.

> What bugs do you mean? I wasn't aware of any bugs in the actual charging
> algorithm.

Mine mostly (always?) starts with -1% fill level.
Are the other issues resolved? (premature cutoff, not starting)
Besides, I don't "like" the algorithm nor the lengthy code:
- It starts to charge after a minute or so instead of right away, which is
counterintuitive. If I plug a device to a charger, I do that intentionelly,
expect the thing to charge. If it's not necessary, it may decide different, but
the default while unknown should be "charging".
- Converting a voltage to a charge percentage is inaccurate, as we know. But
the algorithm takes only such readings, iirc it deliberately discards
readings while the disk is on. Instead those are the interesting ones, I'd say,
measuring how it does under load.
- Our charge current unfortunately is so low (~300mA, we can't do anything
about it) that we don't need to worry much about intelligent algorithms like
for rapid chargers. The cells are not gonna explode from this. If you have
>2000mAh cells, this current is very conservative. You could simply always apply
that, until reaching an upper limit.
(Diava, are you listening? What about your re-write of it?)

> > It's not hardware, but I don't recommend the deep discharge option. The
> > modern NiMH cells don't need that, you add extra cycling to them which
> is not so
> > good for their lifespan.
>
> So if you keep the charger permanently connected, which would be best,
> constant trickle or deep discharge? I'm not a battery expert, but I
> thought that deep discharge would save the batteries in this case.

For permanent connection, I'd say trickle if the detection works correct, to
keep them full. Deep discharge would cycle the cells, right? Or what does
our deep discharge do? Haven't looked, but to my understanding such an option
would not charge until the voltage reaches a critical level.

Jörg

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