Yea, I forgot about that. I had the formula for watts to amps in my head, but
I forgot that if I took the resistance of the defroster I could get my power
needs that way. BTW, does that work for horns too? Is it as simple as finding
the resistance of the horn?
James Nazarian Jr
71 MGB roadster
71 MGBGT-V8 in need of paint
01 Impreza 2.5RS
A complex system that does not work is invariably found to have
evolved from a simpler system that worked just fine.
On Wed, Jun 06, 2001 at 11:52:54AM -0500, R. O. Lindsay profoundly declared:
> James Nazarian Jr wrote:
> > Listers,
> > Can anyone tell me how much power (in amps or watts) the defroster on the
>GT draws? I am building the harness for my V8 and would like to put the
>proper fuse on this component. If anyone can measure one that works I'd
> Paul, check me on this but if you have a multi-meter you should
> be able to work it out.
> I = E/R
> I is current in Amps, the units fuses are rated in
> E is voltage. 12 Volts in this case.
> R is resistance in Ohms. This is what you can read on your meter.
> Measure the resistance of the defroster coils. This should be a
> rather small number so good, tight connections between the meter
> leads and the defroster connectors is paramount.
> Should you read 3 ohms, the current is 4 Amps. This does not
> mean that you should fuse it at 4 Amps as that is the operating level,
> hypothetically. Paul can give you better advice about the best fusing
> level. I would use 50% over the operating level IF the wiring will
> support that current load. I suspect that the current will be noticeable
> higher so the resistance will be smaller. Being in the denominator
> of the equation, the measurement error becomes enormous.
> Paul, comment?
> Theory is theory but 'noise' is not included. Being a big fan of
> empirical data, I would rather hook it up to a 12 volt battery through
> a high current ammeter and measure the load directly -- then fuse
> Rick Lindsay
> Diamond Geoscience Research
> 5727 S. Lewis Ave., Tulsa, OK
> Voice: +1 918-747-3456
> Fax: +1 918-747-8599
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