| Re: Re: Kenlowe electric fans Posted by Jminerva on August 13, 2001 at 21:33:15: In Reply to: Re: Kenlowe electric fans posted by Scott on August 13, 2001 at 00:26:05: Putting on the Bosch alternator is a great idea, and like all great ideas there are nuances. Most BMW alternators are mounted on rubber bushings An inadequate size wire for grounding confuses the alternator, as the Bosch regulator uses the difference between the output voltage at the BAT terminal and the alternator frame as a reference, any voltage drop will mislead the regulator, and if the ground drops our the regulators lofe is very short indeed. The same large wire requirement should be noted for the output wire as well, it is not uncommon for a hard charging alternator and a small output wire to drop a volt between the alternator output (BAT) terminal and the battery terminal. If the voltage regulator 'sees' 14.2 volts difference between the alt frame and the output, it assumes the battery is being charged. In the US this is often a problem on police cars with all their radio equipment in the boot and at the end of long cables. Also, and I cannot transmit the graph over this link, the output (and life) of all alternators drop as the temperature goes up. Back in the 'old' days when we did not have all the electrics we now use in the summer the alternator was cooler in the winter when the electrical load was the highest, and it charged better in the cold. Toward that end, may I suggest that one fit a thermodisc type thermostat under the bonnet and wire it into a fan so that it runs when the under bonnet temp is high, as when pulling of a high speed motorway and parking. The underhood temps often reach over 300F, causing great harm to rubber components and fuel injection parts. Many turbo cars sold in the US have fans that are ducted over the fuel distribution rail just for this reason alone. I usually feed the fan though a diode to isolate the switch from the rest of the fan controls, and install an old heater blower rheostat to run the fan a bit slower and thus reduce the current required. As always, your comments are welcome. Jminerva
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