6 replies to this topic

[duirace]

I just bought a 1963 Morris Mini. The battery was installed with the positive connected to the long insulated wire and the negative connected to the bare short wire. The bare short wire is connected directly to the body of the car. I was looking at an electrical diagram in the manual and i believe it is saying that it is vise versa. So I switched the wires according to the diagram and everything worked the same.

Is this correct? How is it on your Minis?

Thank you in advance!

[Bungle]

a mini of that age should be positive earth

has some one converted it in the past ?

do you have a modern head unit in it ?

[Big Guns]

Hi there. As above, that "should" be + earth but, if someone has played with the dynamo you can reverse the polarity. Has it got a radio fitted? If so it's a dead give away by checking the radio earth.
Cheers.....Dave

[duirace]

after i switched the polarity to be + earth, the radio stopped working. it's and old analog cassette radio. should i just switch the battery back to - earth or should i modify the radio connections to work with the + earth connection? and i have no idea which radio wire is the ground because the wires are all spaghetti.

ps it has a 998cc engine, if that makes a difference...

Edited by duirace, 17 October 2009 - 11:34 PM.

[Bungle]

if you have a raido fitted i would guess someone has converted it to negative earth in the past

[Dan]

At the risk of insulting you, which is not my intention, I'm going to suggest that if you thought it was a good idea to swap your battery polarity without first knowing what was involved you should not be working on the electrical system of your car. There is plenty of oppertunity for starting a very serious fire or even causing an explosion when working with your car's electrics and this kind of thing is exactly where the danger lies. Has the car been updated to have an alternator rather than a dynamo? If so that may have been quite thoroughly damaged by doing this. Are there any other electronics fitted to the car? In future, please ask before you do anything like this, there are people here who can help you.

[dklawson]

Dan has already voiced my concerns but I do want to take a moment to point out a couple of related things.

The fact that your car has/had a cassette player (along with the boot wiring) indicates that your car had it's earth converted. Your tape player is likely "dead" after hooking the battery up the way you did. You have given it a power enema. If your car has a dynamo, it's likely you have done the same to it and/or the control box. IF the car was also converted to have an alternator, you HAVE damaged its internal controls.

See this article at Mini Mania on polarity conversions:
http://www.minimania...81/ArticleV.cfm

If you do not have a multimeter, go buy one. Read the article above and put the wiring back the way it was. Replace any damaged fuses. Measure the battery voltage both with the engine off and with the engine running and let us know what you find. Fortunately there is little to damage on the early cars. However, you now need to make sure the car is fully operational and correct any damage that has been done.