Thread: Battery charging voltage
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skatebiker is offline skatebiker
2009-07-27 , 17:36
Posts: 542 | Thanked: 117 times | Joined on Sep 2008 @ 52 N, 6 E
#9
Originally Posted by Den in USA View Post
Skatebiker, sorry I got confused. Solar panels contain "cells" that are wired in series to abtain the needed voltage. That voltage changes according to the amount of sunlight. Apparently the panels today contain voltage regulators such as yours. In the old days we had to add external regulators.
Each crystalline silicon cell is 0.45 V but the voltage does NOT change much dependant on sunlight. See the diagrams here:

http://en.wikipedia.org/wiki/Solar_c...ircuit_current

which confirm my measurements. Measuring the voltage of my small panel (loaded) it measures 8.4 V in full sunlight and 8.1 V in overcast sky. It contains of 18 cells in series which makes 18*0.45 = 8.1 V.
Here a picture of the panel :

BTW, DealExtreme sells 6 V 200mA (maybe 5.4 V as they have 12 cells according to the image)
http://www.dealextreme.com/details.dx/sku.18168
for only $17 which can be switches parallel and be used as a USB or Nokia charger.
Last edited by skatebiker; 2009-07-27 at 17:38.