Weird battery issue

[prj]

Voltage has very little to do with idle quality...
It's the alternator load. Your voltages are perfectly normal, better than at least 80% cars I tune.

[A80Avant]

So you are saying that no matter what voltage the alternator is giving as soon as its load is reduced by the use of extra electrical equipment its would still have the same effect on idle? Fair enough.

My only concern is if these voltages would still allow for the battery to slowly drain itself and not keep for the amount its suppose to

[prj]

I think your voltage is plenty high enough, I've seen cars charge at 12.8-13.3 volts and the owners reported no battery problems whatsoever. In fact they had no idea the voltage was so low, and their cars still started in -10C winters without problems.

I haven't read the whole thread, but you should probably check your power drain on the car and also maybe you just have a bad battery.
Usually if you fully discharge a lead acid battery, then it will never be as good again.
So if you had issues with it going flat a few times you're gonna have to change it.

[A80Avant]

Yes indeed that was also one of the things we considered.

My drains are measured at 0.08 initially then 0.03amp with the alarm armed so we kind of ruled out the drain.

People on this thread suggested that I should more or less see no less than 14v on most of the times which is what made me worried.

Its reassuring to know that other cars have similar voltages as mine.

[colm9944]

What kind of car is it?

[A80Avant]

Audi rs2

[colm9944]

I've been plagued by this by b4 audis in the last few years, found out by accident a year ago that it was a boot light that was staying on. Not sure about the avant....

[A80Avant]

I had issues with the lids. Now all replaced with leds and they don't draw much current even when they are on.

Only thing mine has is due to the lower after run pump temp sensor the car will often during the summer have the fans working after a drive to keep the temps low. However that has never been an issue in the past even in Greece which was more common to happen due to high ambient temperatures as well.

[Pirvu Eugen]

What do you mean by splice in the cable? For what? In the rs2 the cables goes from the drivers side all the way to the battery well hidden under a plastic cover under the carpet. Due to the engine bay being crowded its hard to see where it goes starting from the alternator but I could trace it while it is in the car.

I also noticed that my + cable is around 0.9mm thick which is rated for 130Amp according to the cables on the market however one shop suggested I got the 170amp rated cable as it seems better for my application.

Now looking at the terminals on the market they are horrible looking and cannot seem to find any that have an additional screw on the positive side for additional cable mounting.

I will try and take a photo of the terminals so that experts in here can shed some light as I feel uncomfortable splicing them out only to replace them with less quality ones. They do seem pretty clean.

So that leaves the variable voltage regulator idea as the simplest one although I do know this is not curring the problem its just compensating for an existing problem.

Given the fact that my cables have been soldered on the terminals what kind of cleaning can I do?

http://www.sjmautotechnik.com/trouble_shooting/elec.html#chg

Look here....maibe is the same with RS2...i dont know..but...worth a check.
All the best!

[A80Avant]

http://www.sjmautotechnik.com/troubl.../elec.html#chg
Look here....maibe is the same with RS2...i dont know..but...worth a check.
All the best!

That is interesting. I will check that. I'm hoping its not the case as the thickness of the cable I measured at the battery is actually one that has a 20mm2 and able.to carry 130Amp alternator. Hopefully that should be near the rear seat drivers side.

Thanks

[Pirvu Eugen]

I cant help you with this..sorry! But...worth a check...and i think... iff is there...should be near the firewall. I think at the wiring instalation in the factory....makes sense to split the wire for easyer install.

[A80Avant]

Hmmm. I will check that once I get a chance

[A80Avant]

This is a photo from audi tradition selling the rs2 battery harness.

If there was a splice, would they be selling it in one piece?

Also etka only has a part number for a 90Amp alternator which doesn't make sense if you are allowed to use a 120amp alternator, you need a thicker cable...

Also is there a part number of a cable from the alternator to the starter?

[A80Avant]

http://www.sjmautotechnik.com/troubl.../elec.html#chg
Look here....maibe is the same with RS2...i dont know..but...worth a check.
All the best!

I got the battery cable from audi tradition today and guess what. Its the same.

A cable to the starter is thinner and joins the main interior cable which is thicker.

I am now wondering if this is the reason for the voltage drop or if there is a need for corrosion to be there in order for the problem to appear.

I will be replacing the entire cable now that I got it and maybe play with the old one to see if I can come up with a joint of a similar width cable to the starter and perhaps reduce the resistance.

[newsh]

Voltage drop will only happen with corrosion or poor connection. I think the thinner cable is the special heat resistant flexible stuff for in the engine compartment. The problem if you have one will be where the 2 cables are crimped together. The ur quatto has one of these joins under the carpet by the driver's foot, in fact it's a T and one leg goes off to the fuse box, caused all sorts of problems on my buddy's car when corrosion got into the crimp, we ended up soldering it.