[Power] [support-gang] 3 portable solar choices for XO-1? (and other XO laptops, if poss!)

[Richard Smith]

On 01/15/2014 12:30 PM, Nathan C. Riddle wrote:

>> the current operating temp.  If that resulting voltage level exceeds
>> the overvoltage level then the XO-1 stops charging before the battery
>> is 100% full.  The actual point at which this happens is very variable.
>>
> Does case 2 apply to the Auria 15W panel of SF 2012?  The output spec.
> is 16.29 volts at 0.944 amps with an open circuit of 19.52 volts.  That
> is, is there sufficent load (XO-1) to maintain the output spec . (in
> Lesotho -- worst case)?  This case 2 did not occur on XO-1's for
> brightest summer sun in Michigan (no noise either). ncr

Since the Auria panels are polySi they have a higher voltage temperature 
coefficient and are less likely to have it happen but they aren't immune.

The voltage output of the panel decreases as the cell temperature 
increases.  So normal usage of the panel works in the XO-1s favor as the 
panel heats up when its in sun.  The end result is function of panel 
tolerance, ambient temp, sun intensity, and what sort of airflow is 
across the panel.

Voc of 19.52V is at STC which is 25 degC but its specified +/- 10% so 
thats really 17.6 - 21.5V.  If the panel is cooler than 25 degC then 
that range will be shifted higher.

There is also variability in the XO trip level.  18V is _worst case_ 
based on the tolerances of the parts in the overvoltage detection 
circuit.  IIRC the typical is around 20V.

So its highly likely that an Auria panel will Just Work but they aren't 
_guaranteed_ to work on all XO-1s.

-- 
Richard A. Smith