Battery, automatic charger, and power supply of Arduino ADK ?


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

Hi guys, did I said something silly ? :roll_eyes: nobody to validate my scheme ?

Where do I take output voltage from ? Power supply/charger or battery ?

Can I use something like that in my "black box" ?

I've some electronic skills but not in Li.Ion battery charging management...

Thanks by advance, Jean-Yves

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 ?

If not , what else do I need ?

thanks in advance

You've not chosen the good horse, nobody replies to me ! :grin:

There's a few extra considerations here:

1) 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. 2) 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. 3) 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. 4) 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.

Hi Chagrin,

Thank you for your reply. I think you have answered my questions.