Thanks very much for the helpful answers, Peter and Roel.
I'm going to try the INA219. The A20 looks great but I want to get the full
mileage out of my old pi 2.
Once I can read the battery voltage I will have to trigger a nice shutdown
event at a certain voltage. I suppose I can set a cron job that checks the
voltage every few minutes. I'm getting power out of the USB port in my 12V
charge controller, which will cut the power itself after the battery gets
too low, but I can't know when that's coming and shutdown gracefully before
hand. It will also turn the power back on at a certain voltage, which
should bring it all back up again.
I guess that means I might get into a state where I've already shutdown my
pi in anticipation of a forthcoming USB power shutdown that never comes, so
I don't get the USB power turning on to bring me back up again. Oh well, I
can live with that. Or maybe I'll get UPS PIco.
On Tue, 4 Jun 2019 at 09:59, peter garner via HBSC <hbsc(a)we.lurk.org> wrote:
On Tue, 4 Jun 2019 08:46:12 +0200
Amos Blanton <amos.blanton(a)gmail.com> wrote:
> I've got my personal website hosted on a rasbperry pi 2 in my
> I want to make some design changes in the coming weeks to localize the
> server in space and time, and play with the idea of emphasizing
> solar. I need to get some data from my solar rig (12 volt, 40 watts
> of panels, and 4 AH lead acid battery) to display on the homepage.
> Anyone have suggestions as to how to get things like battery
> voltage / charge state from a solar rig into a raspberry pi? I've
> been looking at various "hats" but haven't found one that makes it
I went through a similar exercise. I'm a real fan of Raspberry Pi but
with solar power I wanted to ensure that as little power as possible
was wasted in stepping-down voltage. So I looked around for an
alternative device and discovered the Olimex A20, which supports
12 volts as standard and will run as low as about 6-8 volts depending
on which revision the board is. I'd say this was ideal for solar power.
* 6-16VDC input power supply, noise immune design up to Rev.I
* 8-24VDC input power supply, noise immune design Rev.J or later
Hope this helps!
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