I just ordered the pickit 3 and most of the parts required by harlequin2's BMS Nodes. I'm going to play with the PIC that it uses for awhile and then look into changing the HW around until it does what I want it to do. As far as the block diagram I have one half done on paper but I'll give all the details in text here:
Inputs:
__Motor Temp
__Controller Temp (high current portion)
__Charger Temp (high current portion)
__Motor Current (ammeter) [between input of motor/output of controller]
__Charger Current (ammeter)
__Total Pack Current (ammeter)
__Total Pack Voltage
__Charger Voltage(maybe ?)
__Throttle Position
__Brake Position
-BMS Node (from harlequin2's design)
__Cell voltage
__Cell temp
__(Cell Node's will self-number each other in SW)
Outputs:
__Controller Safety Cutoff (Relay to disengage the controller from pack)
__Charger Safety Cutoff (Relay to disengage the charger from pack)
__Pack Safety Cutoff (Relay to disengage the pack's mid way to reduce voltage) [maybe]
-Advance output module
*TBD
-Basic output module (dash lights/gauges)
__Speedometer
__Temp (User programmable)
__Tach (User programmable)
__Volt (User programmable)
__Fuel gauge
__Check engine, oil, coolent, transmission, etc lights
Software ideas:
Use the temp. gauge and dash lights to indicate if there is an issue. For example if the motor is too hot light up the check engine light, and show a relative (cold/normal/hot) measure of temp of the motor.
If the battery is hot or cold light up a user selected light and show the temp gauge at the relative temp.
This can also be applied to the speed controller and the charger.
This board should handle the "logic" circuit of driving a motor, and may be best incorporated with Paul's upcoming universal motor controller; I plan to integrate his design on this board, or at the very least communicating and controlling it.
The basic principal is that most of this stuff is redundant. You need to monitor pack voltage for the LVC and HVC in the charger and controller, as well as the BMS for balancing the cells. If each component uses $2.50 in parts that is $5 that could be spent on an LED dome light upgrade
This system should maintain a 'safe' car regardless of how haphazard a device is. The speed controller for example will be cut off if it is giving power with no throttle command, and the charger will be cut off if its voltage is too high or too low, or if it is putting out to much current.
I'm not sure if I want one or more parts broken into "nodes" besides the cell nodes. The least amount of parts tend to be less expensive, on the other hand I don't want excessive wires running about if the cost of the wires would seriously offset the cost of making a small node board. A 2 wire com's system should be fine for talking to some small nodes, for example you could have a node in the front that tells you all this information, or you could simply have a node behind the dash board with smaller length wires plugged into each light socket and dial versus running them to where ever the main board is at.
I'm open to any suggestions, ideas, comments, etc. Tell me if its a good idea, bad idea, etc I don't mind provided you can answer 'why' or 'why not'