m II wrote:
...
Post by m IIhttp://www.web7days.com/led/index.php
I'm wondering how the wattage is being rated here. The ad says UP TO 2
and a half watts. The numbers say 10 volts at greater than 1 ampere. To
me, that's TEN watts. What's up?
They have written the specs very poorly and I believe this is the
source of the confusion.
This might give you a slightly better understanding.
http://www.web7days.com/led/details.php
: detechable 210 x 210 cm solar panel weight 260 grams
: max 9.55 Volts 500mA
This is likely STC rating on the panel which should be de-rated
some 10 to 20% for the real world. Instead of 4.78 watts it's
more likely 4 watts.
: Ni-MH 12 V 1300 m Ah battery weight 250 grams
This is 12V, 1.3 Ah battery or 15.6 watt-hours. Disregarding the
finer details, it would take around 15 hours to drain that battery
at 1 amp and 1.5 hours at 10 amps. It also looks very much like
the kind of battery pack they use in laptops.
They also include a charge controller and accessory kit, including
a digital volt meter. The charge controller has to step up the
voltage from the panel to something high enough to charge the battery.
Starting with a flat battery, it might take some 4 to 6 'sun-hours'
to fully recharge. This is about what most places get during a full
day, on average.
I don't know how good the product is but it seems to me that you
could probably roll your own version for less.
Anthony