Elite Cdti Alternator overcharging?

[yoda1724]

Vectra Elite Cdti 05 plate died last night on the wife with what appeared to be classic alternator failure signs ie lots of lights on one after the other and then power steering failure.

Went to it this morning and trickle charged the deadish battery via big jump leads for 20 mins and drove her 5 miles home with no problems at all.

Father in law picked up a voltmeter? (has a loop at the top which went around the maind red wire from the alternator to the battery)
Car was charging at around 14 initially and then 19 with lights and heater on. When when revved under load was the pushing out a massive 31.5

Before i spend on a replacement alternator i just want to check that the readings above are signs it is overcharging before looking at other possible faults.

Thanks in anticipation

[Critch]

The hip around the wire is inductive and measuring current flow

Use multimeter in volts mode with wires across batt terminals

best bet take a static batt reading
take a cranking batt reading

take a voltage reading once running at idle
same again with all load. Ie lights, heaters etc

then again at 2000rpm

then take measurements at the back of the alternator
how do they compare to batt readings?

[cont1204]

Clamps normally read amps don't they? Might be worth checking on that. A proper multimeter on the positive and negative terminals will show the correct voltage or failing that, if you have the standard stereo in the car you can use that to see the voltage. Hold down settings until you hear a beep, then press BC to cycle through the test menus. One of them will show the battery voltage. Should be between 13.8 and 14.4 running normally. Probably dropping a bit as things are turned on, then it'll catch up. If it was really kicking out 31.5 volts, you'd be blowing the thing up. The battery wouldn't take it, nor would any of the electrics. Be popping fuses everywhere.

EDIT - if you wanna have a laugh with the clamps, turn the steering wheel from lock to lock and watch. Serious current!

[yoda1724]

Going to take it to an auto electricians Monday to get everything tested, father in law is great mechanic but electrics not his thing to be honest. Have to rely on my RX8 now until next week, talk about irony
Is the power steering pump electric powered then i take it given it wouldnt work last night, seems a tad scary given the engine is till powering the car

[cont1204]

Power steering is hydro electric. Electrics powering the pump. Something isn't right and I'd bet it is the alternator just failing but not overcharging. One of the first things to go when the alternator fails is the power steering because it sucks the most current.

[Critch]

If he's a mechanic then he knows where connections are

and carrys out the above tests then theirs a good chance of finding the fault without paying out any cash