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Positive earth
Posted: Wed Oct 06, 2021 12:56 pm
by whistler
Just about to start reassembling my 66 SDL and need to decide if I'm going to stick with positive earth or switch to negative earth. I'm keeping the dynamo and voltage regulator.
Need some input on pro's and con's?
Can't remember if the fuel and temp gauges are polarity conscious or not.
Re: Positive earth
Posted: Wed Oct 06, 2021 1:43 pm
by woodypup59
Fuel and temp gauges - if original - are not polarity sensitive.
Radios, tachos and the newer (electroic) type of voltage stabilser for the gauges are likely to be polarity sensitive.
Re: Positive earth
Posted: Wed Oct 06, 2021 2:01 pm
by Peter Laidler
I would say that the only reason to keep it +ve earth is if you want to keep the old 1966 radio.( - or to satisfy the originality fiends). If not, change to -ve. Thinking on my feet, 1966 mini is simplicity itself. As Woody says, voltage stab and gauges are OK. Done it a few times. Ammeter wires will need reversing.
Re: Positive earth
Posted: Wed Oct 06, 2021 2:29 pm
by whistler
Peter Laidler wrote: ↑Wed Oct 06, 2021 2:01 pm
I would say that the only reason to keep it +ve earth is if you want to keep the old 1966 radio.( - or to satisfy the originality fiends). If not, change to -ve. Thinking on my feet, 1966 mini is simplicity itself. As Woody says, voltage stab and gauges are OK. Done it a few times. Ammeter wires will need reversing.
Thanks Peter.
Re: Positive earth
Posted: Wed Oct 06, 2021 2:29 pm
by whistler
woodypup59 wrote: ↑Wed Oct 06, 2021 1:43 pm
Fuel and temp gauges - if original - are not polarity sensitive.
Radios, tachos and the newer (electroic) type of voltage stabilser for the gauges are likely to be polarity sensitive.
Thanks.
Re: Positive earth
Posted: Wed Oct 06, 2021 3:52 pm
by mk1
I would ask why?
If you have a REASON to change from Pos to Neg then maybe it makes sense, if not then why bother?
Re: Positive earth
Posted: Wed Oct 06, 2021 4:13 pm
by surfblue63
I would only change to -ve if I was upgrading to an alternator. As Mark says why bother otherwise.
Re: Positive earth
Posted: Wed Oct 06, 2021 5:06 pm
by whistler
I may upgrade to an alternator in the future and it's easier to install a negative earth radio than to make an insulated box if it stays as positive earth.
Re: Positive earth
Posted: Wed Oct 06, 2021 8:32 pm
by AndyPen
My old rev counter was positive earth - so may set our 1071 up that way. Our SDL 970 is negative earth these days.
Re: Positive earth
Posted: Wed Oct 06, 2021 8:41 pm
by Andrew1967
mk1 wrote: ↑Wed Oct 06, 2021 3:52 pm
I would ask why?
If you have a REASON to change from Pos to Neg then maybe it makes sense, if not then why bother?
I converted my Mk2 998 Cooper to Negative earth years ago .. no idea why and haven’t bothered since on other projects, as no real reason to do so.
Re: Positive earth
Posted: Wed Oct 06, 2021 9:35 pm
by Dearg1275
If you want to charge your mobile phone on the move safely negative earth is the way to go. If you are happy to walk to the next phone box positive earth will get the job done.
D
Re: Positive earth
Posted: Thu Oct 07, 2021 8:37 am
by snoopy64
I left my mk2 positive, I just bought a pos earth radio there’s plenty around
Re: Positive earth
Posted: Thu Oct 07, 2021 2:14 pm
by gs.davies
Dearg1275 wrote: ↑Wed Oct 06, 2021 9:35 pm
If you want to charge your mobile phone on the move safely negative earth is the way to go. If you are happy to walk to the next phone box positive earth will get the job done.
D
I never really did get to the bottom of this - if a phone charger is plugged into a cigarette lighter socket which is wired and insulated so that it behaves as if it's positive earth, what will happen to a phone plugged in if it comes into contact with the car's metal work..?
Re: Positive earth
Posted: Thu Oct 07, 2021 2:20 pm
by mk1
gs.davies wrote: ↑Thu Oct 07, 2021 2:14 pm
Dearg1275 wrote: ↑Wed Oct 06, 2021 9:35 pm
If you want to charge your mobile phone on the move safely negative earth is the way to go. If you are happy to walk to the next phone box positive earth will get the job done.
D
I never really did get to the bottom of this - if a phone charger is plugged into a cigarette lighter socket which is wired and insulated so that it behaves as if it's positive earth, what will happen to a phone plugged in if it comes into contact with the car's metal work..?
Nothing. A mobile phone is not a car. All cases on mobile phones are insulated from the works inside. The biggest issue with doing what you describe is an accidental short between the charging socket & the car's body which could be quite an issue unless it is correctly fused.
