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Rechargeable battery power on FEZ Domino


#1

Hi, I’ve been looking around for a way to enable the domino to run on rechargeable internal battery power and I’m looking for some help. I will be putting the device in an enclosure, so I do not want to do rechargeable AA batteries, for example.

On sparkfun, they have some lithium polymer batteries and charger logic, but those are only 3.7 volts. Does anybody know of any batteries and chargers we could use to power the Domino?

We’re hoping for something like say, your blackberry. It runs on battery power, but when plugged into usb it will charge and switch back to battery power when unplugged seamlessly.

I found this charger http://www.sparkfun.com/products/726
This charger has the charging functionality I want, but i am unsure if those three headers means we can charge 3 batteries at the same time? and by connecting two 3.7 volt batteries would I have 7.4 volts to connect to the FEZ Domino?

Thanks in advance!


#2

FEZ needs 3.3V to run so you can use the 3.7V battery with very low drop out switching regulator (good options) or use couple diodes to drop the voltage to 3.3 (bad option but works)

Even better, use a nice switching regulator to pump up the voltage from the battery to 5V then use the 5V to power everything in your system

If you are going for enclosure then consider FEZ Rhino


#3

Thanks Gus. I’m looking into using the switching regulator. It seems all of the regulators I find regulate the voltage downwards to 5 volts, not upwards.

I’d either need to find a regulator that pumps the voltage up to 5V or determine whether or not that charger combines the output of the batteries to the load terminal in series or in parallel. Would you happen to have any knowledge about that charger?


#4

I believe that charge will let you have more than one battery at a time; which means w/ 2 connected you could regulate down to 5V :wink:


#5

Something like this :
http://www.sparkfun.com/products/8290 (300mA max)
or
http://www.adafruit.com/index.php?main_page=product_info&cPath=10&products_id=14 (500mA max)
or
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260682572462 (500mA max but I someway doubt that)