944 charging problem.

1990 Porsche 944 cabriolet

I've been trying to track down this problem for a while. I have a radar detector that also outputs battery charge (not an exact reading, I know!). The trend in battery output has been decidedly down, to the point where the low volt warning sporatically comes on the car temporarily loses power for a few seconds.

Things I have tried:

  1. Had the battery recharged at the auto parts store.
  2. Replaced the alternator.
  3. Disconnected a faulty digital gauge the previous owner had put in.
  4. Tightened down a loose bolt connecting the ground strap from the battery (it had some yellow corrosion on it).
  5. Checked and cleaned battery terminals.

Right now when running, a voltimeter reading at the battery says 13.5 (no accessories) and 12.9 (AC full blast, headlights on). These readings seem low to me (I've read that the reading should be around 13.8 or more).

I've been told that there is a ground from the engine to the transmission, but I don't see anything like that under the car. Someone also mentioned insulation flaking off and causing grounding problems. Didn't see anything like that though.

What else should I check?

Thanks folks.

Reply to
Mr. Crash Davis
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measure the voltage beween the engine block and the battery neg terminal with all the stuff you mentioned turned on. Meaure the voltage between the alternator output and the positive terminal of the battery under the same conditions - report results

Reply to
Bill

Given that my alternator has a big ole plastic air hose and housing on the back of it, is there another place along that path where I could get a reading?

Bill wrote:

Reply to
Mr. Crash Davis

Reply to
Bill

Somewhere you should have a braided copper wire grounding the engine to the frame. Typically it is at the top back of the engine near the heater valve. You may need to careflly clean the contact surfaces.

Earlier models had problem keeping up with full electical load, light etc. 12.5V at full load is OK. If less then you may have poor output from the alternator.

Reply to
darthpup

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