Battery charging Voltage

[islandjj]

Hi,
my sons just brought a Corsa 2005 sxi
It failed to start the other day, flat battery ? RAC guy said it was a faulty alternator. When I measured the charging voltage across the battery it was about 14 .1 V but fluctuated down to 12 and below !. I wonder if this is a sign of poor earth, bad connections , measured the alternator casing to battery ground .02V. Battery indicator light is on and goes off when started
Any advice would be much appreciated
Also If I disconnect the battery will I lose radio , as I've not got the code for it

Kind regards

[johnny]

It sounds like a failing alternator, what do you mean by charging voltage, as in there was a charger attached or the car was just idling

[coupe77]

I would check the earths as the alternator is charging
Have a look at the alternator see if you have an earth from the body of the alternator to the engine block

[pdrpaul]

yes you will have to obtain code if disconnecting battery if its standard.. fluctuating voltage is normally a sign iv found with a bad voltage regulator at alternator when idling does all lights on the car flicker even slightly??

[ukhozi]

Get a PP3 9v battery with a pair of wires on. Strip the ends back 5mm and then stick the wires into the earth and ignition connection on the radio connection block. This will be enough to hold the code memory while the battery is disconnected for a while.

[ukhozi]

Sorry, that should be 12v live not ignition of course.