I've some questions about battery, automatic charger, and power supply of Arduino ADK.
I'm planning to use an Arduino ADK with a Android smarphone for telemetry system on a race moped.
Here is the context : - My moped do not have battery, - My rotor/stator can deliver 12V / 90W, - I can get 12V DC regulated (approx 14,5v in charge) from a regulator, - I need my arduino board alive even if the moped's motor is stopped, - I want to use the ability to charge smartphone via the USB port, - There will be many sensors connected to my Arduino board (temp sensors, relays, linear displacement sensors, knock sensor, egr sensor, rmp sensor,...), - I want to know when battery is low, to prevent dysfunction.
I've read that Arduino ADK is a USB Host, so the smartphone connected as a USB Device can use the USB connection when it need to charge. In this case, it is advisable to use a 1500mA external power supply, I also read that the external supply must have at less 7V, otherwise the 5V pin may supply less than five volts and the board may be unstable.
The solution I found : - The current from the regulator will be used to charge battery with an automatic charger, - I've planned to use a 7,2V / 2OOOmA battery (two 3,4V 18650 battery), - The arduino board gets its power from the battery, - I use a digital input to inform my application that battery is low, - I will kill Arduino power with power button.
The hypothetical scheme of the installation :
My questions about the "black box" : - Am I right ? Is it a good approach ? - Is this scheme achievable ? - Where can I find automatic and intelligente battery charger which is capable to charge two 3,4V battery, and notify when battery is low ? - Do I use Lithium Ion or Lithium Polymer batteries ? - Is 2000mA battery enough ?
Thanks by advance, Jean-Yves