Charging system woes....what is this component?

[PropellerHead]

Gurus,
I'm chasing charging system issues with my '71 911T. I removed the alternator and had it tested (clean bill of health) as well as the external voltage regulator which was suspect and thus, replaced. I still have an issue however as the voltmeter registers less than 13V when running and the batteries are not charging properly. The next step is to remove and check the batteries themselves, but they are hardly used. They were new Porsche dealer sourced and sitting on a shelf in the garage for the past 2 years. I gave them a fresh charge and they seemed to hold fine.

I noted this component on the console in the engine bay, what is it? It is connected to the voltage regulator.

Help!


Thanks,
Chet

[proffighter]

Here we are (#8):

[PropellerHead]

Roland,
Thanks! It doesn't seem to match perfectly with the rest of the layout (in my case I have several different components due to the year, options, etc) but certainly the #8 component looks like a match!

Next question - I could care less about radio noise suppresion, it seems to be in-line with the voltage regulator, any risk in removal in case it is causing an issue?

Thanks,
Chet

[dicklague]

Load test the batteries before you do anything else. the Battery is the LAST thing people want to think is bad. Batteries are very very unreliable.

A friend who was in the battery industry a long time told me that 10% never leave the factory because they fail final testing.

So be sure your batteries are good. Have someone load test them, or get a tester. I have a Harbor Freight tester and it cost like $20.00 and has been a very valuable tool for me.

My '73 would not hold a charge recently. I charged up the batteries and it was fine for a few days....but if I left it a week it would be down again.

I test both batteries and one would drop to 8 volts under load [after a full charge] I disconnected that battery and the car has been great on one battery. I will replace the other one soon.

[PropellerHead]

Originally Posted by dicklague

Load test the batteries before you do anything else. the Battery is the LAST thing people want to think is bad. Batteries are very very unreliable.

A friend who was in the battery industry a long time told me that 10% never leave the factory because they fail final testing.

So be sure your batteries are good. Have someone load test them, or get a tester. I have a Harbor Freight tester and it cost like $20.00 and has been a very valuable tool for me.

Will do, that's step #1 going forward. I (like you suggest) am skeptical of the batteries since they are essentially 'new', but I will indeed load test them individually to rule it out.
I'd really like to get this sorted out soon. I've been working on the car for months to get it back on the road and this issue has me scratching my head. I figured even with a weak/dead cell on one battery, the running system voltage should still be well above 13V? But perhaps not.

[stlrj]

After you rule out the batteries as the problem, you might try adjusting your voltage regulator.

I've always managed to get 14V with this adjustment. It's a matter of removing the VR cover and bending the metal adjustment tang with needle nose pliers to slightly increase tension while monitoring your voltmeter.


Cheers,

Joe

[proffighter]

Originally Posted by PropellerHead

Next question - I could care less about radio noise suppresion, it seems to be in-line with the voltage regulator, any risk in removal in case it is causing an issue?

Chet

You can delete without any issues

[PropellerHead]

Okay, turns out dicklague's hunch was correct. I have one of the two batteries with a dead cell. I don't personally have a load tester.......but the car works for that too. I charged them both up and connected one at a time. One battery turns the car over fine while the other won't budge the starter. Couple that with a discharge to ~10.5V while disconnected and I'd say it is toast. It still is odd to me that they are so 'young' in use yet one has failed.
I think I'll be converting to a single battery soon. I'm a mechanical engineer, this electrical stuff is for the birds!

I didn't have time to start/run the car last night to confirm that the charging system voltage was correct without the dead cell battery connected. I hope it is since I have a new voltage regulator and a 'good', bench tested alternator.

Thanks for the help!

Cheers,
Chet

[PropellerHead]

Originally Posted by stlrj

After you rule out the batteries as the problem, you might try adjusting your voltage regulator.

I've always managed to get 14V with this adjustment. It's a matter of removing the VR cover and bending the metal adjustment tang with needle nose pliers to slightly increase tension while monitoring your voltmeter.


Cheers,

Joe

Joe,
I replaced the old contact VR with a new transistor type. I presume you're talking about the bottom cover on the original type contact VR?
I still have that unit, perhaps I'll take it apart.
Thanks for the tip.
Chet

[jmohn]

Personally, I prefer the "old" electro-mechanical regulator (they're "servicable") but, when I was a kid, that's all there was and we had to learn how to service them. Remove the cover, clean the contacts and adjust for the amount of charge you wish. I'm not familiar with the unit on your '71, but my '78's voltage regulator has an adjustment screw to set the rate of charge (more accurate than bending the contacts). The default charge rate of 13.1-13.5 volts is, in my opinion, to low, but be careful not exceed about 14.5 volts or you may "fry" some of the electrics including your battery (I have had mine set for 14-14.2 volts for about 6 years with no problems).

Jerry M
'78 SC