I have 07 justa and last night I took postive battery cable off and it died. Ive never seen this on other cars are minis diffrent ? Ive seen post with people saying that you can and cant was hoping to hear from somone who had personal exp doing this.
Thanks

 

This is how I test for a bad alternator. the car should remain running.

 

Question: Why did you remove the cable?
Usually if a car shuts off after you remove the battery cable, it means the alternator is bad....

 

In my general experience this a great way to damage the voltage regulator...

Where did this practice come from as a test for anything?

 

correct...removing the battery cable is not a valid test for checking alternator integrity....damage to ECU can be done also.....I have had people disconnect the cable from the battery and end up replacing much more than just a bad alternator....and the alternator wasn't even bad to begin with

 

Thats how I have done it for 20 years,that being said this is by far the newest car ive worked on and just because ive dont it that way for ever does not mean that its was right I was taking the cable off because I was trying to disconect this amp that was hooked up.
Thanks for everyones feedback.

 

Flame Flame Flame. He asked a question and I answered. If you looked at my post, the First QUESTION Was, WHY DID YOU REMOVE THE CABLE???????????????
You guys need to CHILLLLLL!!!!! I would use a voltage meter to test if my alternator was charging......SMH

 

I've worked on cars pre ECU/Electronics (Points/Condenser). Yes, that was one of the ways that alternators were tested on the cars to see if they were charging, how do I know this, because I was an autorebuilder (Starters/Alternators/CV Joints/Carburetors/Rear Ends) On today's cars, removing the battery terminal is not the correct way to test to see if the alternator is charging,but it still yields the same results despite what the pundits here state. To make this clear, Removing the battery cable is not the correct/Ideal way to check if your alternator is charging, it may cause issues on the other electronic and possibly burn them out. Get a voltage meter and save yourself some headaches.

 

To do a "field test" of your alternator -- turn on the a/c, radio, high beams to create a good load. with the rpms at 2000 you should get 13.5 volts or more across the battery. If the alternator can't produce, either the alt is weak, worn, or the wiring is creating too much resistance -- ie: bad ground etc...

Back in the daze of auto generators pulling the battery cable while the car was running guaranteed blowing the integrated fuses of the voltage regulator...
Now with more delicate and complicated electronic everything -- the idea of creating voltage spikes by pulling a battery cable while the charging system is operating is...

 

Back in the daze GM and Chrysler were the only American units that had integrated voltage regulators, the regulators nor the alternators had fuses, they still don't. Those unit have not much changed in the past 40+ years