🚀 go-pugleaf

jeffn@nuchat.sccsi.com (Jeff Noxon) writes:

>Question 1: How can I power the motherboard?  I am interested mostly in
>efficency.  Would 5V regulator ICs do the job as well as anything?

Not really. I worked for a couple of years for a company that made
mainly automotive electronics. All non-trivial equipment had a
switching power supply with efficiency figures on the order of 90+
percent. The switchers started oscillating at around 6 V and after
that could deliver the rated voltages at as low as 5.2 V of input,
although this requires some black magic. Low operating voltages are
needed to keep the power supply working properly during engine start,
which causes a severe drop in the battery voltage.

For your purposes you will probably be happy with a simple step-down
switcher, which is easy to implement using a dedicated IC. One of
Texas Instruments' analog application data books has a very good
introduction to switching power supplies.
You will also want to be aware of how to do load dump protection.

>Question 2: How much battery life could I expect?  I have never seen
>car batteries with amphour capacities stated

All normal car batteries sold here have something like "60 Ah" printed
in huge letters on the side. I have no idea of the load current for
which this holds.

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