[Mgs] problems with ground etc

[Barney Gaylord]

Dave, --- Likely nothing wrong with either of 
those devices, and they should both work okay.

The starter motor draws up to 200 amps at 12 
volts, so internal resistance is nearly nil, 
something less than 0.06 ohm, and it does look like a short to ground.

The Dymano puts out up to 20 amps at 16 volts 
max, working against 12.6 volts open circuit 
voltage of the battery, so only a few net s to 
drive he current.  So dynamo armature resistance 
is also very low. Think how fat the wires are in that armature.

The generator field coils may draw something like 
2-amps at 12 volts, so maybe 6-ohms resistance 
between the "F" terminal and gound on the housing 
(but I don't recall ever measuring it).  Power 
input requirement is not much more than a pair of 
brake light bulbs, maybe half of the power draw of the ignition coil.

Barney Gaylord
19589 MGA with an attitude
http://MGAguru.com


At 04:05 PM 5/12/2023, dave northrup wrote:

>The attached 2 pictures show the generator and 
>the starter.  I think there are problems with 
>both.  Rebuilding the car from scratch with a 
>new wiring harness; the dpo just used red, blue, 
>and black so I cut the wires out.
>
>The two tabs on the generator – both show a 
>connection to ground with a multi meter.  I’m pretty sure that’s bad.
>
>The post on the starter – it too shows a 
>connection to ground with a multi meter.  That’s bad, too, right?
>
>Actually, I’ve used 2 different multi meters 
>with the same result.  And by ground I mean the chassis of the device itself
>
>No battery installed yet, and the rest of the 
>car is disconnected from these devices.
>....
>Attachments:
>starter.jpg
>generator.jpg


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