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positive earth alterntor

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TWF
Posts: 126
Joined: Wed Mar 09, 2016 7:10 pm
Location: Liverpool

positive earth alterntor

Post by TWF »

Hi, has anyone purchased a Positive earth Dynamator and if so ,has it been a success as an alternative to changing to Negative earth ?Regards , Terry .

tjt77
Wise Man
Wise Man
Posts: 525
Joined: Wed Mar 23, 2016 7:01 pm

Re: positive earth alterntor

Post by tjt77 »

I do know of one person that has purchased one, but its not yet installed .. (I still have his engine under rebuild) there is quite bit of discussion about these units on the web and a lot of it is negative.. however.. Id have thought by now that any significant problems would have been addressed and corrected.. these units have been viable for at least decade of not longer..although positive earth units are a recent development..
this is info is something I'd really like to gain more knowledge on... alternators have long since replaced the old generator/ regulator set up .. in automotive applications and would seem to be the way to go..

John Chatfield
Posts: 78
Joined: Mon Feb 22, 2016 11:00 pm
Location: Shrewsbury England

Re: positive earth alterntor

Post by John Chatfield »

Hi Folks, Would any one know if a standard Alternator will fit under an SP bonet I'm thinking of switching from the standard dynamo please?
Regards,
John

User avatar
Jez
Posts: 89
Joined: Mon Feb 15, 2016 8:00 am

Re: positive earth alterntor

Post by Jez »

My SP250 has a standard Lucas Alternator and, from what I remember, Passport shows plenty of others have also been converted.
On mine, the regulator box has been completely removed and the output connected to the 'car' side of the ammeter, along with the connection to the lighting switch. The ignition warning light wiring needed extending / replacing to connect directly from the alternator back to the light.

Cheers - Jez
Jez Stow
1960 Daimler Dart
and a few other toys

tjt77
Wise Man
Wise Man
Posts: 525
Joined: Wed Mar 23, 2016 7:01 pm

Re: positive earth alterntor

Post by tjt77 »

Just quick note on a 'side effect' of alternator conversions.. it came to light about 25 +yrs back, that when converting to alternator on many Uk built cars,(tryically converting an overheated jaguar to more suitable GM power train) IF you are using the additional electrical power that an alternator produces, and running to through the ammeter.. the ammeter would often burn up due to inadequate capacity for the current passing through it (not an issue on a SP.. but can be a common issue with cars that have have A/c added on) and the rectification was to use an XJ6 'voltmeter' wired in parallel (i.e. full current does not pass through it) to replace the old ammeter.. .

kent sutton
Posts: 46
Joined: Tue Feb 23, 2016 10:15 pm
Location: Townsville QLD

Re: positive earth alterntor

Post by kent sutton »

As an adjunct to tjt77 post I have upgraded my car to an alternator. Surprisingly it was cheapest to go with a Chinese copy (and I mean an exact copy) of an 85 amp Bosch unit. Did not like the idea if something went wrong of a full 85 amps going thru an inflammable body!! so installed an inline fuse of 60 amps. As well I upgraded my ammeter to a 60 amp unit (from standard 30) to have the heavier contacts to carry extra load (electric cooling fans) and not to be left beside the road with burnt out contacts of the original unit. I wonder just how much they would take after 58 years of service?
Yours
Kent

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