Re polerising a dynamo

[daverclasper]

 Hi. I have read that this should be done, every time the battery's disconnected (which I do frequently, to give a trickle charge, as battery not charging properly, at the mo).

Is this correct, do you know, never heard this before?.

Also. is it just a second or so, battery pos, to field terminal, will any longer cause harm?.

Also read that, if this done too often, it doesn't work?.

 

Just looking to get the original set up working if I can with my time/free/cheap, before going to the prince of lightness (alternator).

Actually, found the genuine Lucas stuff pretty reliable on my car (In 5 years, only electric problems (apart from occasional modern plug and one bulb, original indicator switch) have been nil.

Never broke down, apart from 2 modern failed condenser's early on (NOS one since then).  

Lucky?, or very impressed.

Mind you I think the wiring was replaced  at some time and appears correct and in good nick and the the connections are maintained to prevent oxidization with AC 50.

I'll shut up now, as could start to feel smug and car will prob break down tom, now I've said all that.

PS. Maybe don't get distracted, (If I should be so lucky) by all my rambling, as would appreciate any answers about the dynamo, please.     

Thanks, Dave

  

Edited September 20, 2019 by daverclasper

[Guest]

31 minutes ago, daverclasper said:

I have read that this should be done, every time the battery's disconnected

Hello Dave,

Personally, I have not heard of this before. My understanding is that once re-polarised that is job done.

You only need to brush the terminal two or three times to reverse the polarity.

Could the battery be on its way out ??

Regards.

Richard.

[daverclasper]

Thanks Richard. I pretty sure it's a charging problem (separate post, just before this one, at the mo).

Have read, it's only once to touch the terminal, though will try that.

Cheers, Dave

[Guest]

You need to see a distinct spark, Dave - if so, that is job done.

Regards.

Richard.

[Pete Lewis]

Agree , only need polarising when first fitted , any activity in afterlife wont affect it .

Pete

[AndyTV8]

Yep, just needs doing once, then job-done

....... Andy 

[Prince Brainier of Meccano]

Yep.  Just one "flash" from battery "live" to the field coil.  This sets the residual magnetic field in the pole pieces the right way for your car. When the generator first spins up it self excites so its important that it starts off in the right polarity.

DON'T DO what I did and due to the close proximity of the battery and the generator, and not having a bit of wire nearby I carefully bridged the gap with 2 spanners.  All ok, didn't short the battery to frame, but when I separated  the spanners the back EMF from the coil nearly chucked me off the wheel!