6v Battery Conection

[StuartA]

Good evening all, 

I recently purchased a 1935 Austin 7 Ruby, can anyone advise if the car has a positive or negative earth, as I believe it changed around 1935/1936. My car currently has two negative clamps on the leads so unsure as to which way round to connect the new battery as the car didn’t have one fitted.

["Slack Alice" Simon]

archive.a7ca.org › collections › handbooks-and-parts-lists


Handbooks and parts lists are available at the above site.

The handbooks do not show the battery poles until 1936, and in that case it is positive earth.

So I would try that first.

[Bob Culver]

Provided noone has introduced any new fangled electronics it is of little consequence and quite simply adapted for either. (Diode for cutout, electronic voltage regulator etc) The ammeter discharge will show how the last owner had it set up. Positive earth cars invite reverse connection by garages, and many in recent years have adopted neg earth to avoid. A prominent marking is prudent.

[Renaud]

When very young I had an old mini. Neg ground which was very inconvenient because i was a licenced "radio amateur" and my home built transmitter was neg grounded. So I simply inverted the battery. I was informed of terrible consequences by plenty of people but of course it worked fine. The dynamo simply changes it's remanent magnetism on the spot and that's it. Of course the ammeter moves backwards, just remember that or change the connection.
Now apart from my radio equipment the was not a bit of electronics in the car!

[Bob Culver]

Seven dynamos sometimes seem a bit coy about a establishing remnant magenetism and the wrong advice in the Williams Specials book confuses many.

[John Mason]

My March 1935 Mk1 Ruby is negative earth (neg connection to the body). It has been like that all the time I have had it but of course a previous owner may have changed it.

John Mason.

[Rick F]

It would be interesting to find out if any components are marked "+ve earth", so that a "doubtful" car like Stuart's can be positively identified (Sorry, couldn't resist that).

["Slack Alice" Simon]

I think Austin realised the car's system could cope with either, since they didn't bother to label the battery terminals in the earlier Ruby handbooks.

[AustinWood]

The +ve terminal of the battery is larger than the -ve. If the leads haven't been disturbed the battery will only fit one way.

[Rick F]

Unfortunately Stuart's leads have - two negative connectors and no battery, which is the origin of his query