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Hi all. It's my first time posting so I apologize in advance.
I have an 89 C4 with 69k that I just purchased 3 months ago. The battery was replaced about a year ago but I'm sure it sat in a dealer lot and had to be resurrected a few times after dying. I have checked all my switches in doors, glove compartment, bonnet, engine lids and they are functioning appropriately. About half the time I start the car the battery warning combination of lights comes on and goes off only when I hit 2k RPM as it should. I brought the battery to the local NTB and the 680 tested at 800 and is good. I measured the charge once and it was at 12.45 and then the next day at the same time it was at 12.1. The warning lights mean the battery was below 9.9 when cranking. I did the fuse check with my multimeter and no parasitic drain issues surfaced. I also used a multimeter and disconnected the ground and didn't get a reading on DC Current. I'm so confused. I even disconnected one of the wires on the positive cable and found that was for the stereo amp. Even with that disconnected the warning light popped on later that day. I would say the warning shows up about 40% of the time. I ordered a 1.5A battery tender but won't that just mask the issue? What do you think is going on? BTW thank you for letting me post to your community. I am excited to join as a member.
Did you break continuity when you pulled the neg lead to test for parasitic drain? You need to keep the multimeter lead on the neg post while removing the car earth or else all is reset.
What is the voltage at idle and at 2k rpm?
Does your interior light always come on when you open the door?
Tracking down battery drains is a process of elimination. As Nick mentioned, first confirm that your alternator is putting out the right voltage at both idle and with the engine rev'ed. Next put a VOM in line with your battery, cycle the key to turn everything on/off. With the key off, what is your current drain? If all is right, it should be between 40-60ma. If your battery is going down that quickly, I suspect you will be much higher. Now, with the VOM still attached, start pulling fuses one at a time until you isolate the circuit. If none of the fuses impact the draw, look for non-standard wiring that may be the source.
Note: The CCU will stay powered for a while after the key is off. Its on fuse #1. Also, be sure to put a clamp on the hood light switch (turn off) while you are testing, as that will turn on both the frunk and engine compartment lights.
What should the voltage be at idle and 2k RPM? Is there a standard target? I will say the voltage rises
from 12.2 to 12.58 volts after a quick 3 minute ride.
Also, I've attached a couple photos of the non standard wiring that is powering my amp. There is a 15 fuse on that wire right next to the ring (about 3 inches off) that is connected to positive. This is the same wire I disconnected however and still had the warning come on.
I should also add that I, of course, didn't keep the Multimeter on the ground post as I was disconnecting and will be sure to do that and report back. I believe what you are saying is disconnect and then attach both, turn the key to on without starting and leave it for 10 seconds or so and then turn it off. Is that right? I also didn't realize that the bonnet and engine bay lid trigger both lights.
With your car turned off and doors shut after exiting, you should read about 12.4 to nearly 13 volts on a good battery. When the engine is running (****), you should read no less than 13.2 for a fully charged battery and 14.6 for a battery needing charging.
**** after starting the car, you need to rev the engine to 2000+ rpm's if you have a single belt RS kit. The higher rpm's will trigger the voltage regulator on. Sometimes with a single pulley system, the regulator will not trigger unless you reach about 2000 rpm. If you have the two pulley system (stock) configuration, you should have the charging voltages of 13.2 minimum to 14.6 maximum depending on the current state of charge on the battery.
Ok. So I tested the levels. I read the voltage after a day of no activity and the battery was at 12.23. I started the car and the voltage dropped as low as 10.5 and leveled off at 11.79. Then when I cranked the RPMs up to 2k the voltage increased to 13.7 and stayed there. What do you think?
I've just had my alternator refurbed - was putting out around 12.9v-13.1v range but is now up to around 13.7v - Indy was expecting it to be up to 14v for his own peace of mind. He thinks there may be an issue with the wiring loom. Battery is brand new as well.
06-21-2017, 12:43 AM
Darned battery warning light
