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'm looking for advice on a similar issue, so I'll post it here.
I need to power an Arduino using battery power. I used a 9V battery which went flat in about 5 hours.
I have purchased a 12V 7A/h lead acid battery to power to power the Uno compatible board which uses a Ping))) sensor and xBee radios to sense and transmit water tank levels, and a 1.26W 18V 70mA solar panel to charge the battery.
Question: Can I simply attach the solar panel to the battery, and the battery to the Arduino Vin and ground without upsetting anything ?
Vehicle power sources are generally quite "noisy" or fully of voltage spikes, both negative and positive. Read up on what a "TVS diode" does to get an idea of how to prevent those spikes from damaging your stuff.
The rule of thumb for charging a battery is to charge it at a rate of 1/10th its capacity. E.g., for a 1000mah battery charge it with 100ma of current.
Don't overcharge or overdrain the battery. The simplest way to check the battery voltage is to use a resistor divider so you can read it within the Arduino's 0-5V range. A 2 cell lithium should be charged to 8.4V (6.4V minimum) and a 12V lead acid to 13.2V. Depth of discharge for a lead acid is a little funny, but try to stay above 11V.
With respect to a solar panel make sure you use a diode so that the battery doesn't discharge into the panel when there's no sunlight.