Ok…now
1.So can I use VIN to connect the panda to a battery instead of the power connector ?
2.What happen if i’m using the power connector while having a battery connected to VIN at the same time?
Don’t take any of this as gospel…
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Yes. I believe Vin is NOT regulated, which means it would be easy to blow up the board unless you’re sure you have nice clean power, within specs, coming in.
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Why? Not sure if you can, but I would not try it.
[quote]What happen if i’m using the power connector while having a battery connected to VIN at the same time?
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Look for protection diodes in the schematic.
Gospel says “check the schematic”. That way you know if things are connected the way it’s interpreted.
From the Panda scematic at [url]http://www.ghielectronics.com/downloads/FEZ/Panda/FEZ_Panda_sch.pdf[/url] you can see VIN has a diode to protect whatever is connected to that from an additional power source. the output is called “+12v” and goes into the 5v regulator which then outputs “+5v” which goes into the 3v3 regulator that then outputs “VCC”
If you were to connect a battery to VIN as well as have a barrel connector to a wall-wart power supply, then you have joined those two directly (the 2.1mm connector and the pin on the header are directly connected). This would be bad without taking extra precautions. I can’t tell you all the things you should do here but the answer is in the subject line of your post - since you’re a newbie, probably don’t go there 
Thanks, now i understand that pin better and also you’re right the schematics help but being a newbie i need sometimes to be pointed to the right direction to understand them
At least I know i cant play with that 
… at least for now 
thanks again
;D 
got my ultimate kit today…
cool…it’s smaller than I imagined…
its’ ultimately awesomely small eh…
Now just remember, no battery and wall adaptor at the same time ;D