3.7V Battery, LiPoly Charger, Setup

I have this charger: http://www.sparkfun.com/commerce/product_info.php?products_id=726

With 1 3.7V 2000mAh battery plugged in: http://www.sparkfun.com/commerce/product_info.php?products_id=8483

To a standard Arduino: http://www.sparkfun.com/commerce/product_info.php?products_id=666

How do I coordinate this with the Arduino? My educated guess is that I can solder some headers onto the LiPoly BAT/GND and interface those with the Arduino POWER Vin/GND, but Vin is made to take 5V? Why is there not a decent "don't blow things up" tutorial with batteries?!

What are you trying to co-ordinate?

You're right in that you cannot power the Arduino from 3.7V. It needs 5V.

Are you trying to power both the Arduino and battery charger from the same supply?

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Well, I'm trying to power the Arduino using one of them. Would this be a V/I=Resistor I would need to put in place to power it? It's all about Amps, no?

I should note the batter is permanently plugged into the LiPo, and it has 3 different connection pairs (5V/GND, SYS/GND, BAT/GND). I was hoping the 5V/GND pair would be wired to the Arduino directly.

Hmmm....here's what I think you could do:

Plan A: Plug in a mini-USB cable to the LiPo charger and short out jumper SJ1 on the charger board. This will make 5V available on the JP1 and JP4 connectors. You can then route this to the 5V pin of the Arduino. Do not, then, ever plug in an external power source to the battery charger (because you might damage the USB port).

Plan B: Plug in an external power jack to the LiPo charger. Again use the JP1 or JP4 connectors on the charger to route this power to the VIN pin of the Arduino.

-- Check out our new shield: http://www.ruggedcircuits.com/html/gadget_shield.html

I will give this a shot and let you know the outcome. Thanks!

Ok, this isn't exactly what I meant: I need the battery alone to power the Arduino while it is still plugged into the charging board (and no USB/wall jack is plugged in). It looks like I will need this http://www.sparkfun.com/commerce/product_info.php?products_id=8999