Dynamo v Alternator

[svenedin]

Oh absolutely this debate has been going on for ever! I first considered the switch to an alternator 33 years ago but since I regard radios as a distraction and undesirable I never saw the need to change from the original set-up. Now I would find a charging port for a mobile phone useful (for navigation and traffic) but there are ways around that with rechargeable mobile phone accessory battery packs or even solar chargers. Something stops me from wanting to change over to negative earth. It just wouldn’t be my car if I did something so radical to it.

[oliver90owner]

Oh absolutely this debate has been going on for ever! I first considered the switch to an alternator 33 years ago but since I regard radios as a distraction and undesirable I never saw the need to change from the original set-up. Now I would find a charging port for a mobile phone useful (for navigation and traffic) but there are ways around that with rechargeable mobile phone accessory battery packs or even solar chargers. Something stops me from wanting to change over to negative earth. It just wouldn’t be my car if I did something so radical to it.

Radical? It still only charges the battery and drives the power requirements of the car. BTW, are you aware that positive earth alternators were once more common than those using negative earth (but not for long)? Likely still available if you search long and hard enough.

[svenedin]

Well I consider it radical. Every time I open the bonnet I would be disturbed to see the battery connected the wrong way round and it would just play on my mind too much so I will leave it original. Yes I knew about positive earth alternators. Didn’t some of the very last Minors manufactured actually have an alternator? Or was it the van? I thought they were negative earth though.

[les]

Each to their own but to describe changing to negative earth as radical is going a step too far ! Maybe changing the engine to a V8 would qualify.

[svenedin]

Watchmaking is one of my hobbies. In watchmaking the wrong type of screw would be considered an outrage!

[Chief]

Each to their own but to describe changing to negative earth as radical is going a step too far ! Maybe changing the engine to a V8 would qualify.

My plan is to switch back to a Dynamo, but I'll keep the negative earth (because I'm a rebel apparently! ) - unless anyone knows how to make a towbar bypass relay work on positive earth.

[geoberni]

Well I consider it radical. Every time I open the bonnet I would be disturbed to see the battery connected the wrong way round and it would just play on my mind too much so I will leave it original. Yes I knew about positive earth alternators. Didn’t some of the very last Minors manufactured actually have an alternator? Or was it the van? I thought they were negative earth though.

Positive Earth Alternators (Lucas 11AC) were fitted to some late Minors, but unlike modern alternators they still had a separate Control Box (Lucas 4TR)
https://www.holden.co.uk/p/4tr_alternat ... 4_terminal
You only have to check the diagram in the Workshop Manual, the last wiring diagram in it is entitled 'Models with Alternator'.

I've read it on several websites relating to Police Vehicles, that Alternators became the Spec for all Police cars, including Pandas, irrespective of whether Minor or not, simply because of the Police early experience with Dynamo equipped cars not having enough power when left idling at accidents etc, and draining their batteries.
The MOD overcame the same problem by fitting military vehicles with hand throttles if they were needed, such as Radio equipped Landies. Although they fitted Alternators as well....
https://fft-keymilitary.b-cdn.net/sites ... k=jccn0X59

[oliver90owner]

Positive Earth Alternators (Lucas 11AC) were fitted to some late Minors, but unlike modern alternators they still had a separate Control Box (Lucas 4TR)

By then, positive earth alternators were history! I doubt that many, if any, positive earth alternators were actually used/installed in the UK - they were the first generation of automobile alternators in the US - and were soon discarded for the negative earth variety.

Back in the late 60s we replaced our dynamos with either ACR 16 (or maybe they were ACR 14?) alternators. These were understood to be ‘derated’ versions, removed from some tractors of that era. Diode packs were not that reliable back then (replacements were £8 IIRC) and several sets were changed, into the 1970s.

My 1970 Escort was fitted with an alternator at manufacture. ACR18 alternators then became the norm and I cannot recall changing a diode pack on any of those. The increase in diesel engined vehicles likely later encouraged the use of 80A alternators, along with more power hungry items being fitted as standard or extras.

It may, to some, be interesting to note that most automotive alternators were (maybe still are?) probably less than 50% efficient after initial warm-up.

[geoberni]

By then, positive earth alternators were history! I doubt that many, if any, positive earth alternators were actually used/installed in the UK - they were the first generation of automobile alternators in the US - and were soon discarded for the negative earth variety.

That's a rather speculative and emotive statement....
Given that the Minor was never produced as a Negative Earth vehicle, they hardly produced the wiring diagram never to use it!

If they were so rare, and indeed you speculate that they were never used... why do ESM find, as a business, that they are worth offering on their website? https://www.morrisminorspares.com/elect ... ls-p829759

[oliver90owner]

Bernie, you may be right but my Mk1 Escort (ex-panda) was definitely negative earth. But, BL was always way behind the US automotive industry in these respects…

The last positive earth vehicle I can remember (that we had) was a 1960s landrover. I thought that all the manufacturers had followed the change,from positive to negative earth, by the late 1960s.

[geoberni]

But the Mk 1 Escort was a '68 launch if I recall, the Minor was 20 years old then.
During the 60s, many manufacturers has older models on Positive Earth and newer ones on Negative Earth.
Some changed over when they updated their model such as Ford changing the Cortina from Mk1 to Mk2 around 1966.
The original Mini started off as Pos Earth, changing in the latter half of the 60s with the Mk2, if I recall correctly, or possible the Mk 3.
The MGB change in 67 when the Mk2 came out.
But the reality was they never really changed anything after the 63ish update to the Minor unless they had to; it was on borrowed time after that. Why change the polarity, with all the potential confusion for garages and owners, plus the expense of altering drawings?

I'd not be surprised if the alternator upgrade was only because some Police Forces wanted it, hence why they kept them Pos Earth to be in keeping with the rest of the cars.
You only have to look at images of Panda Minor engine bays to see many/most of them are running dynamo systems, because there was no 'standard' Panda spec across the 140 odd Constabularies that were sourcing cars.