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Old July 21st 20, 12:57 AM posted to rec.aviation.soaring
Dave Nadler
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Default Ventus CM starting problems

On Monday, July 20, 2020 at 6:34:42 PM UTC-4, 2G wrote:
On Monday, July 13, 2020 at 10:08:36 PM UTC-7, Tango Whisky wrote:
The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.


If you are not using a scope and a current shunt to measure inrush current you will never see the peak current, and it is the peak current that the starter electrical system must deliver to get the starter rotating and generating its back EMF that reduces the current.

Tom


Right, I expect that 50 amps is the steady-state cranking current,
and the initial current to be MUCH larger. Diagnosing a problem with
a much smaller motor I measured 130A peak for some 10s of msec.
As Tom says, you need a scope and current clamp to really see the detail.
Hope that helps!
Best Regards, Dave