chewg

Over the last couple of months, I've had my battery die on me numerous times. Since my last battery was more than 5 yrs old, I decided to replace it. Having had the new battery for a month now, I am still having my battery die on me. Here is what I have tested so far.

1) Battery drain
On several occasions, I've checked my battery drain (using Adrian's procedure) and the reading has been consistent. The drain is approx 50mA, and from doing a search on this forum, I gathered that this is acceptable.

2) New Battery
I trickle-charged the battery and when fully charged the voltage reading is 12.9V. I can use a fully trickle-charged battery for approx 2 days.

3) Alternator output
I start the engine and let it idle for a while. At idle, I measured the voltage across the battery terminal. I did this procedure on several days and the reading was 13.6V, 13.3V, 13.4V and 13.6V.
On the day that the idle reading was 13.3V, I held the engine rev at 1500 rpm, 2000 rpm and 3000 rpm and the voltage reading across the battery terminal was 13.3V, independent of the engine rev.
Again, my search on this forum says that the voltage range the alternator should be between 13.8V to 14.2V.

4) Voltage regulator
No idea how to check this component.

Do I need a new alternator?

Thanks in advance.

Indycam

"Do I need a new alternator?"
It sure sounds like you do . I just bought one , $214.55 for a bosch rebuilt , $150 core , free shipping .

Bill Gregory

Porsche points out it is very important to check the drain in a certain manner. Although I could have missed it, I don't believe this is described in Adrians book. The process is:

a) Run the engine

b) Shut down and wait at least 20 mins for the CCU to 'release' the electrical system

c) Connect your meter leads to the negative battery terminal and ground wire before disconnecting the negative ground wire.

d) Disconnect the negative ground wire from the battery, with the meter leads still attached. This is important because there may be relays in the circuit that are powered, and by disconnecting the ground from the battery first, they will reset.

e) If high ma draw is indicated, proceed with pulling fuses/relays as described in Adrians book.

chewg

Bill,

Thanks for the procedure. Tried it, and the reading was consistent with previous readings (approx 50mA drain).