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On one trip my nice new engine started to overheat at idle. I found that the electric fan fuse had blown. My Berli has a side exhaust which drowns out the fan noise so I did not know until I switched off!
I suddenly had one of my "great ides". I found a super micro blue LED in my toybox which I mounted very close to my temperature gauge. The connection was made to downstream of the fan relay in the fan feed cable. The LED was of course fitted with the correct series resistor and connected to earth. In the workshop it functioned correctly, indicating when the fan was powered up.
When I took it out on to the new fast A30 the blue LED lit up and stayed illuminated at any speed above 45mph! I had forgotten that the fan is rotated by the slipstream! Being a permanent magnet motor meant that it behaved as a generator and fed a nice fat voltage to the LED.
I have solved this by placing a 50A FRED (Fast Recovery Epitaxial Diode) in series with the fan feed, after the relay. This has cured the problem.
Why didn't I just place the LED in paralell with the fuse? It would have been much simpler and would only light when the fan relay makes but the fuse is blown! Drat.
I guess you all knew that the fan windmills and produces power when the car is in motion but I just suffered tunnel vision and ignored/forgot that fact!
More blind alley wheezes soon, watch this space!
I suddenly had one of my "great ides". I found a super micro blue LED in my toybox which I mounted very close to my temperature gauge. The connection was made to downstream of the fan relay in the fan feed cable. The LED was of course fitted with the correct series resistor and connected to earth. In the workshop it functioned correctly, indicating when the fan was powered up.
When I took it out on to the new fast A30 the blue LED lit up and stayed illuminated at any speed above 45mph! I had forgotten that the fan is rotated by the slipstream! Being a permanent magnet motor meant that it behaved as a generator and fed a nice fat voltage to the LED.
I have solved this by placing a 50A FRED (Fast Recovery Epitaxial Diode) in series with the fan feed, after the relay. This has cured the problem.
Why didn't I just place the LED in paralell with the fuse? It would have been much simpler and would only light when the fan relay makes but the fuse is blown! Drat.
I guess you all knew that the fan windmills and produces power when the car is in motion but I just suffered tunnel vision and ignored/forgot that fact!
More blind alley wheezes soon, watch this space!
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