Fuel Level Sender - Dash2 or DL1?

[peterguk]

Hi Everyone

I'm installing a Dash2 and DL1 in my Noble, and believe i am the first to do so.

Questions on fuel sender unit:

I'm replacing the rubbish OEM float-type sender (that only works in the middle third of the tank) with a VDO tube-type sender unit.

Reading on the forums, am i correct in saying i'd be better inputting the signal into the DL1 as opposed to the Dash2 due to a much slower refresh rate?

Also, the resistance of the sender varies between 0 ohms and 80 ohms. So a 100 ohm resistor would be correct?

[osborni]

Yes, 100 Ohm, but take care with how many sensors you drive off the internal power supply. You may want to add up the total amp draw if you are driving more than a few sensors.

V = I*R

or in the case of a pull up:
V / R = I

Opinion, but feeding a sensor into the DL1, will give you more control on how the data is sent to the Dash and then post race analysis. You get to control the update rate from the DL1 to the dash, where if you direct wired it to the Dash, you don't get to control that.

For fuel, you will probably want to average over a very long period with a 1-5 hz or so update rate over serial.

Most of my analog sensors that go into the DL1 feed the dash2 as 5hz and I average them over 3-10 samples. It is a trial and error thing.

[Peter Carroll/Toronto]

I personally like to put car related stuff directly into the Dash so is will still work without the DL1 being present. You can still control how to average the reading on the Dash.

[peterguk]

You can still control how to average the reading on the Dash.

Can you tell me how to get the fuel reading refreshing as slow as possible through the Dash2?

Thanks.

[Support]

Hello,

[img][img]http://s28.postimg.org/6joltnfft/DASH2.jpg[/img][/img]

It is not so much the refresh rate you need to slow down as this would still give you massive variation of the fuel level. What is needed is filtering which has 2 options on the DASH2.

1) Maximum rate of change
2) Number of sample to average over

1) Maximum rate of change (red box above) is in the configured units per sample, i.e litres, gallons or %). The DASH2 analogue inputs sample at 30 times for second so to set a maximum rate of 1 litre per second it would be 1/30= 0.3

2) Number of sample to average over (green box above) is adding all the values of samples together and dividing by the number of samples. DASH2 analogue channels sample at 30 times per second so if you set 100 it would take the sample from the last 3.3 seconds and output the averaged value. For fuel level the maximum setting 100 is best.

*** If the fuel level data is coming from a DL1 the sample rates well depend on the configured output rate. The default is 5 times per second.

Kind regards,
Support (K)

[Halsbury Racing]

I am fairly sure that the DASH2 has 30Hz sampling and the DL1 is 100Hz or optionally 1000Hz, so you would be wasting a valuable fast channel if you connected the fuel sender to the DL1.

[Danielviach]

Thanks for the detailed response.

If connecting the earth to the tank directly is the bodge how do I fix it properly? Can I pull apart the sender and re-connect the earth or do I need to get a new sender.

Thanks,

Tim

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