Ferrari Mailing List: Re: 308/Mondial window motor current

[Rick Lindsay (rolindsay]

Yep.  E=IR

I am just interested in the maximum current if the window motor is stalled.  
e.g., if I stick my head in the opening and press the switch.  Or better said, 
in case the window is slow and in crap condition.  I want to fuse for worst 
case, not operating case.  That's why I am searching for worst case or 
"stalled" motor.  I don't want the fuse to "fuse" when the motor stalls.  
Rather, I'd like the fuse to NOT blow when the window stalls but TO fuse when 
some stupid Houston driver t-bones me and crushes the power wire into the door 
frame. 

Happy Friday everyone.

rick


--- On Fri, 11/21/08, robert_h_bowser [at] juno.com <robert_h_bowser [at] 
juno.com> wrote:

> From: robert_h_bowser [at] juno.com <robert_h_bowser [at] juno.com>
> Subject: Re: [Ferrari] 308/Mondial window motor current
> To: "rolindsay" <rolindsay [at] yahoo.com>
> Cc: "The FerrariList" <ferrari [at] ferrarilist.com>
> Date: Friday, November 21, 2008, 10:56 AM
> If I remember correctly, the equation is:  I = V/R 
> (Ohm's Law)
> 
> So...rule of thumb...to get the maximum, simply measure the
> resistance in the motor windings (at the motor) using a good
> Ohm meter, divide that value into 14.5 (nominal voltage),
> and you get maximum current (i.e., stall speed current). Set
> the fuse at 1.5 to 2 times that value and you should be OK
> (assuming the feed wires and all other elements of the
> circuit can handle that current/voltage).
> 
> Not sure why you want the operating current value, as it
> does not relate to the fuse requirements.  The current draw
> will vary depending on the rotational speed of the motor and
> the load it is subjected to.  I imagine it should be on the
> order of 1/3 the max value.
> 
> Of course, I'm an electronics engineer who has never
> taken any engineering courses, so I may be wrong.  But I
> have had my 308GTS for almost ten years now, and it has not
> caught on fire...yet!
> 
> Bob
> 
> -- Rick Lindsay <rolindsay [at] yahoo.com> wrote:
> Hey techno-gimboids (like me),
> 
> What is the average operating current of a 308/Mondial
> window motor?  And what maximum or stall current might one
> expect for a sticky or stuck window?  I ask because I want
> to run large gauge power wires to my doors and I want to
> fuse them appropriately close to the power source.  The size
> of that fuse and the gauge of the wire is related to the
> stall current of the motor, thus my query.  Advice?
> 
> rick
> '83 Mondial QV
> '79 308GTB
> other stuff
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