Leave the bonnet up, tape or depress the bonnet button, lock all the doors either with the key or the fob, take the batt off, shut the bonnet.

When you get back to the car, open it with the key in the hole, open the bonnet, replace the batt, bob is your uncle.
 
there’s no criminals in Australia:confused:

All reformed!

As I said, battery is fine with starting and everything else, and is only a few months old - just a bit surprised with the static voltage I measured - 12.3V; with alternator running it seems around the correct mark - 13.9V. I read somewhere that it should read 12.7V for a 12V battery (just over 2.1V per cell). As someone said, it could be DMM inaccuracy? I am going to buy a pulse-type charger (C-Tek) later to replace the hand-me-down, ancient, no-frills basic charger I have at the moment - I suspect one or two "flat" batteries I had in the past could have been "recovered" with a more high-tech charger?!
 
I have just checked mine. Yesterday I measured about 12.2V but the car starts fine every time and was used regularly for 30-40km trips. I have a Ctek charger with Recond mode so I put the battery out for the night and made a recond program on it. Today morning I measured 12.6V, put back the car, started, measured after 12.4V.
I will take the car now for a longer run and see after how much it has recharged itself.
Note: my measure equipment could be a bit inaccurate as on my wife car (which has new battery) I also measured only 12.4V (so maybe 0.1-0.2 down).
 
Those voltages are not very relevant, as long as the voltage doesnt drop below 11V(minimum 10.5V) while cranking that battery is up to the job cos even if it has 12.7V in the morning it can drop below 10.5V while cranking as it can have low CCA and then it's weak.
 
Battery is 1100 CCA and 130 A/h - so maybe the static/resting voltage thing is a non-issue? I did read where it said if the static voltage is 12.0V then the battery is considered to be fully charged or "flat" (think it might also have said 12.3V is 50% discharged!). Anyway, will stop worrying for now!
 
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the resting voltage gives you an idea of the state of charge of a healthy battery. if its connected to the car and the ECU is awake, it will be artificially low as a result.
if the battery is unhealthy, its possible to have a good resting voltage, but a dead/dying cell will drop off as soon as you connect a load, thats why drop tests are useful, eg measure the voltage while the starter is engaged
 
So use DMM and get someone else to start the engine - should try that and see how far it dips! Thanks. I have another vehicle that seems to be very susceptible to small voltage drops - one issue was the rear electric brake - had me scratching my head - nothing wrong with the brake, all fine when a new battery was put in!
 

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