Alternator overcharging

[KS]

Open to experience-based suggestions!

Parked the 914 in October in lock-up after final event. Retrieved it couple of weeks ago and discovered that when running, it was showing close to 16 volts on the voltmeter. Checked across battery terminals to confirm. I had a spare regulator (it's the same external voltage reg as used on early 911s etc), swapped it over but still showed close to 15 volts, which didn't change when driving.

This side of electrical systems is a mystery to me - why might it start overcharging after doing nothing for three months? As it's not just one but two regulators, both of which I know to have been OK and one of which was stored indoors, I am at a loss as to why after a period of inactivity this problem has arisen.

Am I overlooking something obvious? I'd welcome any input from electrical gurus out there in DDK-land!

[middlefour1]

When mine did that it was the alternator that was at fault. Its not an easy job to replace but in my case it solved the problem.

[KS]

But what i don't understand is that it was perfect until laid up for several weeks. Hmmm...

[Lightweight_911]

.

Have you checked the state of your battery when disconnected ?

If your battery is defective (eg has a dead cell) it could cause the alternator to overcharge in trying to compensate.

.

[KS]

Engine off - 12.6v across terminals.

[911hillclimber]

Measured my 2 12V 911 batteries, neither exactly 'young' and both had 12.6V out of the car on the bench.

[Nine One One]

Are all the earths clean
Others have said they had to replace the circuit board the Voltage Regulator plugs into - appears the earth prong if pushed too hard into the board can push through it causing an issue?

Others have reported dodgy new regulators (Chinese copies)

This thread may help
http://www.914world.com/bbs2/lofiversio ... 66557.html

[KS]

Are all the earths clean
Others have said they had to replace the circuit board the Voltage Regulator plugs into - appears the earth prong if pushed too hard into the board can push through it causing an issue?

Others have reported dodgy new regulators (Chinese copies)

This thread may help
http://www.914world.com/bbs2/lofiversio ... 66557.html

Yes, I've been scouring the 'World' and have come to the same conclusion. Time for some checks with an ohmmeter... Cheers.

[KS]

Looks like I might have sorted it. First removed original voltage reg and sprayed the terminals (both male and female) with contact cleaner, which helped slightly. Replaced VR with modern solid-state aftermarket unit and voltmeter now shows 13.6v charging.

Half my electrical gremlins can be traced to living in Cornwall, I'm sure. Damp salty air causes everything to corrode or rust in short time. The RH headlamp suddenly stopped popping up and down. Removed relay on that side, sprayed the terminals and hey presto, it works perfectly once more. Cornwall may be god's chosen county, but it does have its downside...

[misteralz]

Invest in a tube of dielectric grease, Keith. Dow Corning used to be the go-to offshore.

[KS]

Invest in a tube of dielectric grease, Keith. Dow Corning used to be the go-to offshore.

Thanks for the tip!