If it's not really about tuning or wiring. Then it belongs in here.
I am developing a lightweight Lithium battery, I am curious what you would like as features.
Specs will be 4 x LiFePO4 cells, 600A CCA, Approx 2kg with a full LCD display.
The real questions I have is would people like a CAN bus port to log individual cell voltages, battery temperature, charging/discharging rates etc? What else would you be interested in?
Guess it depends on the market you want to reach. You are looking probably looking at motorsports with that weight saving, I say a CAN port would be a good idea, as it would be an easy integration for the end user and data is key to motorsports.
I'm really not an expert in Lithium batteries, but don't they need a different charging process than normal Lead-Acid batteries, like would you need a special alternator, or would it be a direct replacement for lead-acid battery?
That would be very cool, especially for endurance cars where we want to know if the car ever stops charging the battery. Since LiFePO4 doesn't really reveal the state of charge from the voltage, I think an internal accumulations of state of charge based on capacity and measured charge/discharge current would be useful.
I think there is a market for batteries of this size and up (say twice that capacity.
Important CAN features -- settable base address, CAN Baud Rate, possible switchable CAN termination (default no termination). Ability to have multiple batteries in a similar address range. For example, if you transmitted all data using CAN ID 0x480-0x483 for battery 1, 0x484-487 for battery 2, 0x488 - 0x48b for battery 3, etc.
Since you would likely need flash memory for that kind of setup, perhaps you could also record number of charge/discharge cycles, minimum / maximums for voltage, current and temps.
Build the CAN bus, then make the (optional) LCD display be a CAN bus device. If I'm using the CAN Interface it's unlikely I need the LCD display as well.
Frank: Yes its a drop in replacement. The Lithium-ion batterys are higher current capacity for smaller weight, they run at a higher voltage and because of that if the seperating material is damaged they go bang. LiFePO4 has higher thermal runaway that LI-ion, well above 250 degrees C, so if your engine bay is at that temperature, everything is probably on fire. Or, if you have mounted the battery next to the exhaust, you deserve a fire. P.S. your picture of drinking beer is awesome.
David F: Bloody gold! exactly what i was after. I was actually thinking of using CAN to use the batterys in banks so that the protection curcuits can work together. I really want to do current sensing, unfortunaly it adds reasonable cost as it needs to be high current (1000A) for starting AND high accuracy for when its charging at