VS V6 battery wont hold power for any longer than 3 weeks.

[1Match&5litresOfUL]

For 12 months,i've had the problem of the battery losing power.Every 3 weeks i have to recharge the battery and since Christmas have gone through 2 new batteries.I've checked all the usual culprits,ie glove box light,interior light to no avail.3 weeks ago i replaced the alternator(brand new in the box) and today i noticed that the 3rd SuperCharge battery again, needs recharging.I've checked all the connections possible(for a novice) and am now starting to wonder if there's something else in the electrical system that is evading me.Hoping someone can advise me of a solution,short of getting an auto-electrician to take a look.Best wishes.

[drewVHSS]

A problem more common on the 5.0L v8 harness but sometimes crops up on the v6 harness is the main charge feed wire from the alternator can break contact after it's warmed up from resistance in the wire/connections due to old age, perished and cracked insulation with ingression of moisture and or oil/contaminants.

Add an extra cable from the B+ terminal on the alternator to the battery (you'll get away with 8 gauge car audio amp wire and two decent ring terminals from repco or supercheap etc if your only adding this wire as an extra to run parallel to the original with an 80 amp inline fuse else run 4 gauge if you intend to remove the original cable)

You'll find on initial startup and for a few mins of running time the battery will recieve charge and then after a while... it'll stop getting charge from the alternator and drain from the battery.

This problem also isn't helped when your main earthing points aren't clean and tightly mounted.
All the earthing straps, main current cable from alternator and main current cables to and from the battery pull alot of current through them, any corrosion or loose contacts increase "resistance" which creates heat in the cabling causing joins to fail.

VS commodores are getting on a bit... you'll find all sorts of electrical issues cropping up more and more.

HTH Drew

[Jonno]

with your bonnet open
all ur doors and everything you can think of turned off

take the negitive terminal off the battery and then tap it back on, if it sparks.. somethings on

[wamboin23]

with your bonnet open
all ur doors and everything you can think of turned off

take the negitive terminal off the battery and then tap it back on, if it sparks.. somethings on

i'd suggest you don't do that anymore than what is a result of taking the terminal on and off.

1. 90% of the time it will spike and you will get a big draw, that will instantly drop to nothing.
2. you'll end up blowing out diodes in all sorts of places if you do this.

[1Match&5litresOfUL]

A big thank-you to all those made the effort and were willing to share their expertise.I'll have a look during the week when i get some time.Best wishes to all.

[Jxw]

a better method is to use a multimeter, a cheap digital will do the trick.

as previously stated, make sure everything is off, doors closed etc etc
disconnect the -ve terminal
now with the DMM set to DC amps range usually 10A, if you're unfamiliar with how to read amp draw and the multimeter has an auto range function, switch it off so it only reads amps and not milliamps etc. With the leads plugged into the correct sockets (DO NOT place the probes across the battery in amps range), place 1 probe on the -ve battery terminal and the other probe to the now disconnected -ve terminal for the car, check how much is being drawn.

Ignore the initial spike as it's most likely the ecu and/or radio drawing an initial charge for their memory, which is also what can cause the initial sparking when you reconnect a battery, wait a few seconds and then read how much current is being drawn.
Also obviously don't try to start the car with the dmm in place, you'll blow it's internal fuse.

If it's an excessive amount of an amp or more then you'll have to find the culprit.

The easiest would be to connect the battery back up normally and take the dmm to the fuse box.

1 by 1 remove a fuse and place the probes on either terminal until you find which circuit the current draw is on, from there it's a matter of tracking down what is causing it, most likely you'll have the door open and the interior light will be on, if you get a reading depress the door switch to turn the light off, if the reading goes away then move onto another fuse, at least you should now have a direction to look and not just blindly look at globes, faulty switches etc.