Nathan said:
Ahh - I have some IRF3205's from another project and kept getting them sitting half way, and so looked at an alternative. can you give me any info on what causes this sticking and what components I would need? No worries if not I will also be searching google now i know its my lack of skill. Its the learning of the project that im loving so much and not the total practicality.
I am using the Atmega328 as there easy to program, will allow me to report the data back to the main data storage systems, done a version of this over i2C for this project for the charge/discharger, took me 3 hours to code, build the prototype and design a PCB that will meet my requirements)
the IRF3205 is and N-Channel mosfet, without a dedicated gate driver with charge pump, it likely wont work unless your switching on the negative side (This n channel turns on when the gate is 2-4V greater than the source pin, this would work, you would just have to make it clear its for the negative side (N channels at this current level are generally cheaper)
The main thing to get them to never be in the linear area of it is to use some strong hysteresis for your op amp operating theswitch, e.g. switch open at 60C, switch closed at 55C, rather than oscillate around 60C, to do this, google images is your friend,
For data comms, the main thing to remember is that each cells board is at a different voltage, so from what i can see, Isolated canbus would be about $6.70 per board, and consume 3mA even when idle, I2C as long as the monitors are slaves, could work very well by one of these per board, yes the bigger one, as he has enable pins that drop the idle current to 50nA,
http://au.mouser.com/ProductDetail/...syD0wnx/ymMtzz4rkLS6uSbapWSvbpqlRUm6Mwn6mtA== , the other thing you could do with these chips would be 1 Wire
The only thing with any commsis you will need a good way to assign ID's before you connected it to the rest of the network, say 2 banks of 4 switches, 1 for bank, one for cell,or have a process where by a non ID'd unit appeared as ID 0, then the controller assigns the next avaible ID, That or use a 1 wire eeprom on board and use that serial number, small cost but reduces problems on micros that dont have unique ID's