ArduScooter 2.0

[ctirad]

I agree with your all your suggestions, but using 1 Attiny for 4 cells with only 10bit will reduce dramatically the precision (last cell will use 1/4 of his precision due to the voltage divider ) and because 1 MCU for each cell still remain simplier than 1MCU x 4cells.

The precision will be best at 5V, which gives you almost ideal range for a lithium cell. And as I wrote above, you have several options to measure mutiple cells without loosing even a single bit of the precision.

[ccriss]

The precision will be best at 5V, which gives you almost ideal range for a lithium cell. And as I wrote above, you have several options to measure mutiple cells without loosing even a single bit of the precision.

Interesting... Which are the options you suggest to keep the measurement precise? Could you give me some example?

Thank you in advance

Cris

[ctirad]

Interesting... Which are the options you suggest to keep the measurement precise? Could you give me some example?

Probably the best possbility is to use opamp as differential amplifier which will transform voltage of every single cell to common ground. Now you can just connect the outputs to the ADC pins of the MCU.

Another possbility is to use resistor dividers and compensate the amplitude loss with variable gain that many MCUs offer. It will be a little bit more noisy, but the digital precision will be kept. Also usage of the differential ADC inputs of the MCU is a good idea.

BTW, do you know this project: http://www.batteryvehiclesociety.org.uk/forums/viewforum.php?f=53 ? The slave boards are exactly what you want to do, just based of the different family. You can just make your arduino master board compatible with their slaves.