dead battery

[c.routhier]

Hi, I have a 66 912, which left me stranded a bit last night. I think I have it solved but wonder if anyone can help. Here's the story, will try to keep it simple.
1] don't drive it much,
2] has new regulator, rebuilt gen, new starter, 1 y old battery.
3] took it out at night, drove it for about 20mins, went to start it few mins later, and just a 'click'
4] waited 5-15mins, got tiny bit more juice but not enough to turn over, then 'clicks'
5] guy jumped me and it started right away. red light working fine, belt is okay seems a bit loose, but not too bad?
6] drove it home, turned it off, went to try seconds later, nothing, just 'click'
whew. here's what i did.
a] next day, put in another battery, fired right up. drove it around, stopped and started just fine.
b] charged the regular battery, put it in fired right up. so checked gen belt, tightened it up one washer.
c] used a multi-meter on battery, got 12v at idle, about 13 at 2500rpm or so. I figure my gen belt was loose and not charging the battery but was good enough to put out red light?

any thoughts? and sorry for long message.
Chuck

[wastintime]

Chuck,
You have to remember that you have a generator on the car, and not an alternator. It sounds like you started out with a near dead battery and only drove it for twenty minutes. After the battery charge has been lowered to a certain point, it has a very hard time "catching up" so to speak and will take a very long time to recharge. Especially with a 66 which has the smaller generator, if you start with an almost dead battery, then you're not going to be able to make up what you took out of the battery starting it in twenty minutes of driving. Probably not even after three hours of driving, especially at night when you have the lights on and drawing electricity.
A loose fanbelt will definitely affect your entire electrical system especially at high RPMs, and if it's loose you should tighten it. Other than that your best bet is to keep your battery charged. Fully charge the battery and then drive the car around for a good while, let the engine get up to speed and stay there for a while. If the battery is still fully charged when you turn off the ignition then you're probably just not driving it enough to charge the battery with the generator.
If it still isn't charging you might want to check out your electrical system. Check the water in the battery, the regulator, etc... From what you descirbed though I doubt you have any problems with your electrical system, and if your battery's voltage output is going up with RPMs it sounds like it's trying to charge.

[adot]

Hey Chuck

Just mea. 13 VDC at Idle and 14.5 at about 2.5k(9 yr son, OK Dad, ITs there) at the battery. I had nothing but trouble with rebuilt generators(3). Went with 68 69 large dia. generator(NEW)

Good luck

Brett

[jac912]

One more piece of advise...check all electrical connections for corrosion and consider replacing battery cables and cable to the starter. Old cables develop resistance.

[c.routhier]

hi, thanks for input, i took the car to a local porsche shop and had them check charging system - all is fine. did find a loose spade connector on starter and battery ground was loose. looks like a combo of loose gen belt and ground? anyway, i just got back from a 500 mi trip to New Hampshire and didn't experience any problems at all. what a great ride.
regards,
Chuck