Re: Diodes Part 2

[Todd Tomason <jayscore@xxxxxxxxxxxxx>]

This is all good discussion, but it doesn't answer my original question.  Why 
have I never seen one of these installed on a car?  This was missing on every 
AMC I've owned (only four I'll admit).  Did people routinely remove these?  

Todd

On Monday 13 December 2004 18:59, david crooks wrote:
>  >You can run one of these Motorola alternators
>  >without the isolation diode but it is like
>  >replacing a fuse with a slug.
>
> True, but I'll return to this in a second...
>
>  >The diode ... is there to protect the internal
>  >diodes which are much harder to replace.  Clip
>  >your jumper cables on backwards and the isolation
>  >diode may go, but the circuit to the internal
>  >diodes should then be open and protected.
>
> Sorry but this is completely wrong.
> The isolation diode will provide no protection
> against reversed jumper cables, it allows current
> to flow in the same direction as the rectification
> diode pack.  It's purely the luck of the draw as
> to which diodes blow first, and the smaller diodes
> in the rectifier pack are more likely to go first.
>
> The isolation diodes purpose is to remove the alternator
> and regulator from the electrical circuit when the
> alternator generating any voltage.  This used to be
> done with a cutout relay, but the diode solution is
> simpler and much more robust.  Your alternator will
> work fine without it, but you'll see two side affects.
> First your charging voltage will by about 0.7 volts
> higher, which is what would normally be lost across
> the diode.  Secondly it eliminates battery charge
> leakage through the alternator when it's not running.
> In other words remove it, and you'll find your battery
> going flat more often...
>
> Cheers,
>

> Dave