Re: Maximum input voltage for "can" style (Lucas/Bosch) ignition coil (fwd)

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Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 17 Aug 2005 16:08:28 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Maximum input voltage for "can" style (Lucas/Bosch)  ignition coil
    (fwd)

At 01:07 PM 8/17/2005, you wrote:
>Original poster: <sroys@xxxxxxxxxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Wed, 17 Aug 2005 12:21:28 -0500
>From: D.C. Cox <resonance@xxxxxxxxxx>
>
>I have used 650 VDC with a 1.5 uF cap in a single shot pulse mode ---
>repeated once every 5 seconds.
>
>Dr. Resonance
> >

I wonder what the likely failure mode would be?

Internal short in the HV winding most likely.  The primary (LV) winding is 
pretty rugged.  However the HV winding is really, really fine wire (smaller 
than AWG40, I'd guess).

They'll take a fair amount of overheating, too.  After all, they normally 
run in a 50-60C environment.  The average current is probably around 2.5A, 
and the loss resistance is around 0.5 to 1 ohm, corresponding to a thermal 
dissipation of 5 Watts.

In normal operation, they fire 100 mJ/spark, and in a V-8 at 6000 RPM, 
there's 400 sparks/second, for 40W total throughput.