MembersPage/RichardBarrington/RangeRoverClassic/Config (2006-03-16 04:43:08)

I know the measurements I've taken are good, and the MAT sensor is within .5C of the K-probe. BUT the coolant sensor is still reading about 4C too low: 13C instead of 17C tonight.

One assumes that Easy Therm hasn't generated an effective curve... so what's the best way to produce one? I'm guessing manual R to ADC conversion + propertherm.pl?

Temperature Calibration

Temperature calibration seems to be reading low. The air sensor is [MSD 2320] with exposed thermistor (100k-50 Ohms), the coolant sensor is a [Land Rover] part.

Some new data, measured by slowly warming a pot of ice until it boiled. This took over an hour, so I'm sure the sensor was keeping pace with the fluid. Measured with a DVM and thermoprobe, and a DVM on the sensor, this curve looks *much* better when graphed in OpenOffice.org. Voltage for ADC calc was measured to be 4.90V at the sensor connector...

TemperatureResistanceADC (Calc)
05690TBD
54670 
103700 
153040 
202470 
252020 
301630 
351360 
401145 
45940 
50795 
55675 
60580 
65480 
70417 
75358 
80307 
85263 
90234 
95198 

The following points were measured, using a digital thermometer with K-thermocouple, and a DVM for resistance:

TemperatureCoolantCoolant ADC (Calc)AirAir ADC(Calc)Notes
-19.81117020520930226Freezer
1.554901719070197Fridge
7.139101516030176Fridge
24.019501072743129Room
40.6102070131083Oven
56.05594469652Oven
68.03853244536Oven
89.02081822319Oven
94.019217  Kettle

Previous readings...

CoolantAir
TempResistanceTempResistance
-166650  
15420  
35430  
  75370
202318203190
212023  
  71480
86242  
88297  
96203  

The air sensor looks like a common NTC part.

I have a TVR Griffith that seems to use the same sensor. I can confirm your readings from your tests are correct, as I've done the same and got the same answer.

I would be interested to know what your coolant calibration in your config is (or what Easytherm says it should be!)

Thanks

David Blades

The .inc I generated with Easy Therm was reading 4C too low at 18C. It's available [here] for reference anyway. I graphed the points and the curve was perhaps slightly suspect, one point anyway? But it doesn't have ot be out by much to mess up the lower temperature values by a few degrees... so I'll go back and do it again with more points, remove outliers, measure aref, etc. To be fair it's much less of an issue than with the MAT sensor, but I still want to get it right.

WBO2 Voltages

Got it sorted after reviewing several other configs. Nothing significant to say, other than to suggest copying Marcell's WBO2 set up to start with...

CircuitTargetVoltage beforeVoltage now
GND -> Pin 5 (pump)3.964.283.96
GND -> Pin 1 (nernst)4.414.394.41
Pin 1 -> Pin 50.450.110.45

Got the hardware completed. The issues seem to be getting it set up as described [here].

I took base settings from the above page, and found that 0x63 was closest to 0V for my board (negative 0.109V). Then inserted 100 Ohm resistors into the socket and took readings (nerst_dc_voltage=8D).

Adjusting nernst_dc_target can change nernst value, but pump is still too high, and difference too small. The linked page states "The product of wbo2_pump_pid_ki and wbo2_pump_pid_ilimit should be around 0x4000" but linked values of 0x20 and 0xFF give 0x1FE0 already? Which is more correct, and how can I use this to increase the pump voltage (assuming nernst_dc_target can reduce nerst voltage independently). I think increasing wbo2_pump_pid_ilimit should work to raise the pump voltage? Or should I increase wbo2_pump_pid_kp instead? (after reading PID links)