OH Photovoltaic Charger
spam_from_qihw at chezphil.org
Sun Jul 18 12:39:05 EDT 2010
Marco Castorina wrote:
> what I really miss
> for my laptop is a photovoltaic charger that would allow
> me to use it in parks or open air in general
I have a nominally 6V 1.5W solar panel of approx A5 size with a USB A
socket. It's similar to this widely-available one but without the case:
When I connect this directly to the NN, the charging LED comes on when
it's in direct sunlight and the terminal voltage is around 4.15V.
Unfortunately I can't easily measure current; since the Li-ion charging
voltage is 4.2V, it's possible that it is just floating without any
useful current going anywhere.
In cloud the light goes out and the voltage drops to below 3V.
Generally, charger ICs do not say much about how they will behave when
the input is variable or feeble, as it is with a solar panel. Perhaps
partly because of this, most solar chargers for things like phones have
a battery; the panel charges the battery and the battery later charges
the device (which it can do with a reasonably constant high-current
output). But this is inevitably less efficient than connecting the
panel directly to the device.
I wanted to look at the schematics for the NN's battery circuitry. So
I went to the wiki, but I wasn't able to find them. Can anyone point
me in the right direction?
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