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Kenlowe fan current draw


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When the Kenlowe fan cuts in on my TR6 the voltmeter reading drops to about 11v (from 14v) and when idling, engine revs fall. Also the 35amp fuse in the fuse box feeding the fan gets hot and has blown on occasions. Assuming it's drawing around 35 amps @ 12 volts suggests the fan is taking around half a kilowatt of power. Is this right? Or is something wrong in the circuit or the fan motor. Any advice would be welcomed as I am contemplating a trip to Italy in July, and will probably be relying quite heavily on the fan to keep us all cool, particularly when crawling up an alp behind bicycles or caravans.

 

Andy

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A relay is a good idea,but your question remains.

 

Those glass fuses are often rated at 17amp continuous 35 peak.

 

I belief the fans can draw 20amp when starting up, hence possible fuse blow?

 

Hth

 

Steve

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Thanks for your replies.

 

Regarding your relay suggestion, Neil, any relay would have to be fitted between the thermostatic switch and the fan motor. The Kenlowe fan kit isn't supplied with a separate relay, so I guess the thermo switch is adequately rated to take the full load.

 

I could separately wire the whole caboodle, but I would still need to fuse it, and I would still get the same problem with overloading the 35A fuse.

 

I'm still wondering if the fan is drawing more current than it should. Perhaps I should just hot-wire it off the battery.

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My fan (which now works...) needs to run off a direct feed. It takes a real pulse over 30amps to start and runs at c 12amps, readings on a smiths ammeter.

 

I run mine from a separate loom linked to the second alternator terminal ostensibly to ensure my ammeter reads "right". Others on here would recommend direct to a fused feed from thye battery.

 

I can't imagine the old loom or fusebox are up to significant loads these fans put on your system.

 

In terms of voltage I can't answer why you get such a big drop but a bosch fuel pump plus a big draw from your kenlowe is going to be close to the peak output if your alternator. Others can tell you if this would cause a voltage drop.

 

Good luck. Snowy

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Hi Andy,

how big is your alternator. If you are getting close or going over its rated output then the volts will drop and the current will go up.

The battery will feed it for quite a while but it sounds like your Alt is suffering.

 

You need an inline fuse 40amps or so.

 

The thermostatic switch is only just adequate to run the fan. A relay is cheaper to replace.

Use the thermo switch to power the relay coil and take your power from the battery connector on starter solenoid through the relay contacts to the fan.

Is the fan rotating in the correct direction - if you are moving forward and it is trying to push the air forward through the rad the current will go up - stalling.

 

Roger

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Thanks guys. I've distilled your advice down to :

 

Need a relay

Bigger fuse

Bypass the fuse box.

 

And I'll probably wire in an indicator light on the dash, as the voltage drop is a useful warning that the fan has started, and I'll really miss it.

 

But its probably worth that to avoid frying fuses and thermo switches and the ensuing steamy dramas.

 

Thanks again,

 

Andy

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Hi Andy,

 

As Roger indicates:

Get a decent 45 or 55amp Alternator. Fuel pump, lights, electric fan etc all should have relays and a fused power supplies. Volt drop equals high currents in these areas which can lead to electrical harness fires. 2 of which have happen in our TR Group.

 

Bruce.

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