steveo said:
Hey Methods
I tried the setting specified in your provious post .. but i have shitty acceleration .. I'm estimating 30-40amps draw on launch .. i didn't measure exactly.. I am using the factory shunt which i estimate is between 80-100 amps.... could you post another screeny of setting that work good or perfectly for you with the factory shunt!
-steveo
Actually, you are seeing just what you should be seeing, so good job!
The factory shunt will give you apx. 30A continuous acceleration.
If you want to get up near 100A cont. you must solder the shunt down to 250uOhms
If you lay two pieces of solder wick on top of the shunt and then drench the entire thing in solder you should get close.
The shunts that Keywin put in are NOT matched to the software. The software expects about half that impedance. Setting the software to the max current (60ish amps?) will net 30 - 40A continuous.
I am currently looking for a better shunt solution. Will probably end up being (4) 1mOhm shunts in parallel. This should better handle the heat and it is very hard to find a single, high power 250uOhm shunt.
Maybe SAM-Pilot can guide us toward the best way to re-scale the current sense circuit.
We dont want to rescale it too far since the shunt cant handle the heat....
Power at 100A for various shunt values:
250uOhm shunt
100 * 100 * 0.00025 = 2.5W
500uOhm shunt
100 * 100 * 0.0005 = 5W
1mOhm shunt
100 * 100 * 0.001 = 10W
So... It may not even be wise to spoof the circuit.
To me it looks like the best option is to lower the shunt value to 250u.
You will lose some resolution but it wont affect the controller performance negatively.
The CA actually has a very good input resolution so you may not even take a hit on your Ah readings.
-methods