vs ute battery keeps going flat

[elliot.j]

i have a vs commodore ute and the battery keeps going flat. it is a hard problem to solve because it happens really inconsistently. i have changed the battery, changed the alternator, and it kept going flat every few days, sometimes longer than others. i noticed my tensioner was pretty flogged out so i changed that thinking the belt may be slipping on the alternator, and it was good for about a 6 weeks than this afternoon after driving home from work, it was flat again.

can somebody please give me a few thoughts???? could the starter motor possibly have anything to do with it???

[BRAWT_4TH]

do you have a sound system ? sub amp ect

[James39]

The battery should not be going flat while driving lol You might have a bad connection somewhere, I suspect the main wire from the alternator to the battery.

If you have a multi meter you can check the volts while the motor is running, you should get around 14 volts at the battery.

[aussie4life11]

check the wire at the back of the alternator as this wire can burn out sometimes i heard

[RX25SE]

Assuming the battery is in good condition, as above, you may have a charging issue.

Connect one end of a multimeter lead to the B+ terminal at the back of the alternator, the other lead to the positive battery terminal.

Start the engine and turn on headlamps, heater fan, rear demist etc to load the alternator note the voltage (drop), it should be no greater than about 0.2v.

If the voltage drop is too high, there is not enough getting to the battery so the battery will eventually go flat.

As mentioned, the B+ cable is prone to melting causing charging issue.