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[Blue]

Hi all, why does my battery on odd occasions go completely flat overnight?   To my knowledge everything is off apart from alarm light!  Your help appreciated, and thanks for your time! 

[flyer 0712]

Take it to a battery supplier and ask to have it dropped tested and then it will tell you whether it is your battery or trouble elsewhere..normaly free to test it as well..

[TheBoy]

Usually a duff HRW relay, powersounder or something else causing high drain. Assumign the battery isn't toast.

[2nddaniel]

http://www.omegaowners.com/forum/index.php?topic=132429.0
 
Have a read, see if it applies.

[zirk]

Apart from posting you drive an Omega (from your profile), model, spec, year, etc would help. 

[ronnyd]

Have heard from someone that a battery drop test knackers it. Is this true?

[flyer 0712]

No it doesent...all it does is to put a high electrical draw on the battery to see if it is ok or not....if it isnt it shows up the faulty cells by them fizzing....or the the needle drops simply because the battery cant handle the voltage required when starting the engine...like everything in life it gets old lol 

[zirk]

Have heard from someone that a battery drop test knackers it. Is this true?

As said, a drop test is just a high current load, not much different to a Starter Motor turning over a cold engine.

[Terbs]

I think the terminology 'drop test' is a bit misleading. It would not suprise me in the least if some plonker has dropped it from a great height.
The info in Maintenance on here by Kevin is spot on.

[johnnydog]

I have had previous problems with batteries being flat only after a few days of inactivity. In each case, the battery was fine. The problem was a faulty powersounder battery. Changed it, and problem solved every time. Presume it was draining the main car battery.
An easy way to check the power sounder battery is to disconnect the negative lead with out switching the ignition on first (the 15 second procedure). If the alarm goes off, then generally the battery is ok. If there is no sound from it, then it is knackered and needs replacing. Another indication that it is shot at, is if it beeps at you 3 times when locking (or is it unlocking?) the car.
There is plenty of info on here about this issue, by the way.

[Kevin Wood]

Yep, power sounder charges its' internal battery at a high rate until it reaches a certain voltage, so it's possible that this could cause excessive drain if the battery is in poor condition. Corrosion across the PCB from a leaking power sounder battery can also cause excessive current draw, sometime to the point that it catches fire.

If the power sounder doesn't work, it's better off in the bin.

[omega2018]

drop test is just a brief (few seconds) heavy drain on the battery while monitoring the voltage.  rac have a laptop that does it using the car's starter as the heavy drain, software then decides how good the battery is based on how much the voltage went down (plus some extra margin to sell you a new battery even if yours is still reasonable).