napaul

alright here is the back ground....this past saturday went to go start car to pull out of garage to wash and it started and then radio went out and little at a time started shutting down till it started idling rough and died.iI placed a charger on it for about 45 min and it fired up and i took it for a drive and has been ok till this morn. Exact same thing happened.Only difference is yesterday i was installing my blue porsche led kit on instruments and had the park lights on in cabin to see when each light bulb lit up.Tried removing dme relay and re installing it in case it was stuck although it is a new one also.

on saturday after being on charger for 45 min and then starting it up i did place a multimeter on the battery posts as it was idling and was showing 12.9-13.1v as it was running. Could it be my battery is shgot and won't hold charge very long anymore i can bring it to work and do load test on it to confirm but if not what should the alternator output be at battery posts during idle and engine rev up to see if alternator is shot cause it has a new rebuilt one?

Rocket Rob

I would do some basic trouble shooting to try to isolate the problem. First check the battery voltage with the engine off. It sounds like the alternator is charging. If the battery is 12-12.5 with the engine off then you have a current drain some where. Look for simple problems like a trunk or engine cover light being stuck on. Once those are eliminated, then put an ammeter in series with one of the battery terminals and then start pulling fuses until you find the culprit. The current draw should be 40-60 milliamps. Remember when doing this test to turn off or unplug the trunk light.

RSAErick

The voltage across the battery with the engine idling should be between 13.8 and 14.4 vdc.

Try increasing the RPM's, and if you can not get the voltage to 13.8 volts by 1200 rpm, then the alternator or regulator may be failing.

napaul

where is this regulator and where \can i find it to test.
also rocket rob i will try doing the basic trouble shooting tonight when i get home....

so at idle when it reads 12.9-13.2 that is not a normal reading at idle at the battery posts? will have to check with a better meter tonight cause the one i used was a cheap and not the most accurate....

is there any value in replacing old fuses with fresh ones do they deterioate over time and build up extra resistance?

Rocket Rob

Its on the back of the alternator. Not easy to access.

I would say not.

Another thing to check, is your battery and ground connections.

napaul

hey rocket i was going to ask you in your original post you said with engine off if i have 12.5 v then i have a drain but shouldn't the battery read 12v anyways if charged and reading across the terminals.Hooking up an ammeter in series i see the logic but is 40-60 milliamps acceptable for an older car or should it be less than that yet. It should only be alarm and constant power to radio that should put out minimal amperage when car is off correct

KaiB

Another thing to check, is your battery and ground connections.

This is the very first thing you should do; not just check, but pull off, clean and re-do. Without proper connections (ground is often the culprit), most other work is futile.

Rocket Rob

The 12 volt batteries should have about 12.5v without a load. See wikipedia article http://en.wikipedia.org/wiki/Lead_acid

Yes, the 964's will have a 40-60 ma drain at all times. According to Adrian's book this is normal. I had a battery going dead problem a few years ago. The faul was my CCU. The best I could get was 50 ma. I suspect the radio, clock and DME are always pulling little bit of power.

napaul

So here is what I did tonight got home and straight to the garage to try and figure out mydead battery issue.....

Checked my ground and 12v wire from battery even took the ground wire off to clean the terminals they are ok now.....hooked up a meter in series by disconnecting ground off battery and putting one lead on ground cable and other on positive terminal with cable still attached put to milliamp setting and only got 0- 0.1 mA so ithink I did something wrong as rocket said 0.40 should be normal.....

Performed a load test and battery rated for 585 cca and it measured 516 cca.....checked charging system with tester and with out load on it 13.31v with load being placed on it which was high beams and heater fan on high it was 13.21v so said charging system ok....

Left battery charging all day and battery had 12.8v so it started fine took for a drive and got a check engine light....checked with durametric and said code 11 dtc and o2 sensor circuit open to b+.....cleared codes and drove light hasn't come on again yet.....took out my ccu to change lights to matching blue led and again battery discharged.....don't know what it is but everytime I've touched anything to do with intrument lighting battery has discharged maybe just coincidence.....this is really starting to suck as I'm beginning to be afraid to drive car and be left stranded with dead battery....

Any body have suggestion to try next I apologize for the rambling on.....

KaiB

Put the meter in series with the ground: Discon the gnd cable and set the meter btw that and the neg post.

Note drain - if its parasitic, start pulling fuses and checking for the circuit at fault.

Not parasitic: Go have a large drink.

napaul

I have to ask cause I was thinking last night is there any wire or component under the engine or near engine I can check for possible cause of not wanting to turn over as though a dead battery cause last friday I put car up on hoist and and sprayed underneath with engine shampoo and then pressure washed off near and around transmission. Could have I loosened some wire or damaged a wire that vibrates loose now....

Where is the starter wire could something around the starter cause these symtoms?

wf758

napaul - did you ever figure this out?

18T_BT

5 years ago? Is he still on the forums?

wf758

You never know if you don't ask...

Andy Roe

He was last on Rennlist yesterday from looking at his profile. Perhaps send him a PM to be sure he sees your post?