Hello, I'm having trouble recharging my battery. On the second to last trip, the battery indicator needle fluctuated randomly. If I remember correctly, it used to always hold steady at 14.3V until now. On the last trip, however, the charging system fault message came on and the indicator was only on lower half, dropping from some 12V to 10.6V within 100km. The car ran without any problem, I only noticed that the wipers were very slow to come on and opening the lights seemed lazy too. It was only at the last junction near the house, when coming to a complete stop at a stop sign, that the charging suddenly recovered and jumped to 14V and stayed there steadily until the engine was switched off. Overnight I had the battery recharged to full.
Today I checked the cables and connectors available from the engine bay, everything seemed to be fine. After starting, the battery gauge stayed around 11.6V. At the alternator I measured around 13V, the reading kept jumping to rather below 13V and the battery was same as the gauge in the car (11.6). After about 5 minutes I suddenly heard something like a whistling sound and the car gauge showed 14V and I measured the same on the alternator and battery. However, it only lasted for a while, before the sound stopped and the alternator was only giving about 13V or less again. The charging system fault message has not lit up since the last trip. Squeezing the throttle didn't seem to affect anything. Batery tester said that my battery should still be good. Is the alternator up for replacement or should I check something else first ? Thank you.

 

Read the sticky post about alternators before you get rid of yours. That post has critical information describing key differences between the original unit any many replacement units that claim to be compatible.

 

To agree with and add to Dads2kconvertible, don't change the alternator, but do take it to a local autoelectric shop and have them evaluate and possibly rebuild or repair it. A good shop -- and that doesn't generally include local parts chain stores -- will be able to spin and load test the original and know if it's brushes or diodes or something else.

 

I agree with advice to have your alternator tested, one thing to check is the connections at the starter solenoid this is where the output cable from the alternator is connected to the battery cable, loose or corroded cables can cause excessive voltage drop.

 

Yes, it looks like it might be caused by loose bolt on starter. I spent last few hours trying to tighten it from top, but theres just not enough room with headers. I give up for today and tomorrow I will maybe try it from bottom.



That doesnt look tight at all...

 

I would remove the cables and clean the terminals, loose connections like those tend to heat the terminals and cause a loss of conductive.

 

Always disconnect the battery before working on stater terminals! You can get some exciting fireworks if you don’t. Fusable links go very quickly.

 

So I tightened that loose bolt, it was awful job but I suceed. Hower when I put everything back together, now that car doesnt start at all.. All it does is just 1 click from starter... My work order was: unplug battery, remove motor cover+air tube+2 spark plugs for better access from top, remove green conector on starter for better acces to that loose bolt, used contact cleaner and slowly and painfuly tightened loose bolt and then reversed that work order. So I think my easiest next steps now should be to check some fuses and try to jump start it / use different battery ? Before I go down to starter again...

 

Make sure your battery is fully charged, one click from starter means not enough power to crank the engine over. Some people who have had loose connections on the starter discover that the solenoid had to be replaced.

 

Battery was recharged overnight, but still no start. Fuses 14 47 50 52 looked ok. Jump start and different battery still nothing, always just that one click from starter.

 

You will have to pull the starter and replace the solenoid, those lose cables on the starter solenoid caused a voltage drop and generated heat which baked the insulator on the solenoid. I know it's probably not what you want to hear as pulling a starter off with headers is a pain.

 

Yes, thats not what I want to hear. But sadly it looks like it so far. Also I noticed, that it might be C6 starter/solenoid in my car, because there is some connecter and I dont see anything like that on C5 starters offered online ? Engine is LS1.

 

There shouldn't be a connector on a C5 starter, most people replace the starter as well. I replaced mine several years ago with a starter that has two long mounting bolts, you might also think of adding a heat shield since you have headers.

 

I checked it again and purple wire is definitely modified for c6 solenoid style. I just dont know, if whole starter or just solenoid is C6 or what model is it at all. Guess I will have to wait until its out, to find more clues about what replacement to order. I begun preparation for pulling starter out, it will be extra painfuly job without lift :/ Heat shield will definitely go on new one, as I dont want to have this problem ever again. I am also thinking about some locknut, because it seems like all that was caused by regular nut going loose.

 

Problem solved. I bought whole starter intended for 2008 base C6 (as my cars purple wire to starter was aleardy modified for plug style) and it fits and run good. Disassembling whole exhaust system because of headers was pain, but car now starts again as it should and battery charging is good again too.

 

Glad to here that you have your car running, and charging.