Startup Problem!

[Stain]

This startup problem has come back again!

Car has been going great... but then will randomly lose all charge in the battery overnight.
Only thing it can power is the "door open" and "park brake" lights... the central locking doesnt work, the alarm armed light doenst flash... even the horn doesnt work!
I've taken it to a auto electictions and they can't find ANY drain on the battery... But I'll take it for a drive on day, and it wont start the next.

Since I've owned it it's gone thru 4 batteries...
The one it came with was flat
I borrowed a mates, didn't work
Bought a cheap BigW one, worked for a few days
Then got a expensive high qual one, and it's done me for months, until these last few weeks of headaches!

If it was the starter solenoid the rest of the electrics would still work, right?

The car has a 4AGE swap
Using a "BlackWidow" alarm system (installed by pervious owner)
Has a aftermarked headunit and speakers (installed by pervious owner)
A water temp guage w/backlight
And a cabin switch controlled radiator fan - which I have since gotten the leckys to rewire to include a relay. (as before it was just going fan->switch->battery)

[Driftspec]

I'm not sure how useful this will be, but out of the list, it looks like the headunit would be the most likely candidate to cause headaches like that. If you haven't already, try disconnecting it and see if that makes a difference.

Otherwise, it could be a alternator/regulator issue, or something between the charging system and the battery not working, ie not allowing charge. If you have a voltmeter and know where to look, you should be able to suss out if there is a problem. Only thing is if is as intermittent as you say, then there may be no easy fix.

EDIT: I broke up the reply from the original topic, bumping like that is never good.

[Stain]

The auto electics ran 2 new wires from the alternator to the battery to make sure its getting heaps of charge.. tested the alt too.

I'll rip out the headunit later and see if that helps.

[ke70dave]

one thing you could try, is stick an amp-meter inline with your battery (a proper guage type, that can handle large currents)

ie, take positive battery terminal off, and put ameter between battery terminal and the battery itself

see if its drawing any current while engine is off, will tell you straight away if there is any small drain (like cd player etc)

you coudl try it with alarm on/alarm off to see if the alarm is drawing any current, it should draw a little bit, but not enough to flatten it

if you have a multi-meter you could use this and get a accurate measurement, just remember most of them are only rated to 10A, so don't turn your lights on while its plugged in, or you'll blow your multi meter.

[ke70dave]

one thing you could try, is stick an amp-meter inline with your battery (a proper guage type, that can handle large currents)

ie, take positive battery terminal off, and put ameter between battery terminal and the battery itself

see if its drawing any current while engine is off, will tell you straight away if there is any small drain (like cd player etc)

you coudl try it with alarm on/alarm off to see if the alarm is drawing any current, it should draw a little bit, but not enough to flatten it

if you have a multi-meter you could use this and get a accurate measurement, just remember most of them are only rated to 10A, so don't turn your lights on while its plugged in, or you'll blow your multi meter.

[ke70dave]

one thing you could try, is stick an amp-meter inline with your battery (a proper guage type, that can handle large currents)

ie, take positive battery terminal off, and put ameter between battery terminal and the battery itself

see if its drawing any current while engine is off, will tell you straight away if there is any small drain (like cd player etc)

you coudl try it with alarm on/alarm off to see if the alarm is drawing any current, it should draw a little bit, but not enough to flatten it

if you have a multi-meter you could use this and get a accurate measurement, just remember most of them are only rated to 10A, so don't turn your lights on while its plugged in, or you'll blow your multi meter.