Battery drains on long trips

[Pjay]

Hi, this forum was recommended by a brother who's found it invaluable for problem solving.

My VS always starts fine after being only driven short distances, but I have trouble starting after a trip to Bris Vegas (130km or so). Happens every time. No warning lights or other symptoms.
Any clues much appreciated. I did try searching, but most battery probs are the reverse scenario...

 

[6 shooter]

Do you know it is the battery at fault? because it either could be the alternator not charging it properly or the batterys on its way out

 

[Darkness 77]

My VS V8 was doing this and it was the brushes/regulator thingo that screws into the back of the alternator. $50 and prob fixed. While this was my easy fix I'm not saying its the only thing that can go wrong. While you've got your head in the bay check all battery connections for corrosion or loose wired.

 

[aceventura]

I had such a problem once - It was the connector on the back of the alternator that came a little loose. See the sticky thread:

https://forums.justcommodores.com.au/threads/vs-v6-owners-check-out.5910

 

[hako]

Welcome to the forum. I'd be more inclined to check the EFI and start relays first by substitution. It's also possible your starter motor is showing signs of wear - when hot sometimes either the solenoid will jam or be sluggish or the starter itself shows high resistance when hot.
Do a codes check also as your description also leans toward a failing Crank Angle Sensor (CAS). Logged fault codes will confirm this and it's easy to perform. I've attached the link:
https://forums.justcommodores.com.au/threads/checking-error-codes-vr-vs-revised.22307
Good Luck.

 

[VrWagz1]

Define "have problems starting". Does it not crank?, does it crank slow??, does it crank normal but dosnt fire up??????????????

Need a little more info to help. Dosnt start could be a million things.

 

[Pjay]

Thanks for the responses - I've learned so much already! I have a Gregory's manual, which has been useful, but this forum is a mine of info!

The only code I get is a 12, so that's reassuring. Symptoms were no problems with starting while driving around town, short distances. But, after a longer drive, the motor would only just turn over, sometimes not enough to fire up. I've only replaced the battery once in 14 years (bought the car new), so a new one went in today. Alternator checked out fine. My query was about the battery discharge being the reverse of the usual situation (fine on long runs, but discharging after short drives). Hopefully the new battery will resolve the issue...

 

[hako]

If you've only replaced one battery in 14 years you deserve a medal. Batteries have reduced capacity when hot so on a long run the battery will get hot due charging and with your battery being so old it's probably sulphated up or whatever reducing it's cranking capacity.
Just out of interest do you have a list of what you've replaced over 14 years and the mileage plus any problems - a lot of forum members would be very interested.

 

[VrWagz1]

It sounds as if your battery may be due, but it may not nessacarilly be the problem. If it continues then you will need to check the main power cabeling to the starter and your main engine earth + chasis to battery earth. If it is all clean, well crimped, no evidence of burnt/corrosion inside the crimp of the lugs then you can only maybe try swapping the starter out as the heat may have taken their toll on the windings. See how you go.