Solar charger (was Re: News Openmoko Shop Pulster)
cheetah100 at gmail.com
Sun May 31 03:26:48 CEST 2009
I thought I would provide some of my experience with using solar
power. My experience involves using a 12v panel. You can get 12v
panels from all kinds of places. In order to step down 12v to the
required 5v you will need an efficient dc converter:
Do NOT use a 5v regulator as you will dump half the power directly
into the regulator as heat. That is not only a waste of power but
potentially a fire risk. From there you can get a connector to the NEO
USB and simply wire in the power. I actually had a PhidgetServo board
and wired the power directly into it. To get my NEO to charge I had to
turn on the external charging and set to 500ma.
The point here is that you will need 5v x 500ma = 2.5W in order to
supply that kind of juice. This power is only available in full
exposure. It also does not account for any conversion loss. I
recommend using a 5W panel. Obviously if you can get a 6v or 5v panel
you could use a basic regulator without much trouble.
This is not a kind of panel you can carry around easily. Some
'chargers' on the market have such low surface area they have no
realistic chance of supplying the kind of juice required for charging
in a realistic time frame.
Here is panel I'm using:
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