Why battery goes flat?

racex, Sep 14, 3:58pm
My battery only 1 year old and charging system fine. After car sits for 2 days I have a flat battery so there must be something drawing current. Any idea what this might be? Cheers
jmma, Sep 14, 4:07pm
Make and model of car may help, has it got an alarm?
Have you had the battery checked?
racex, Sep 14, 4:14pm
Honda HRV. Yes the battery has been checked and tested fine. It did have an alarm but has been disconnected.
m16d, Sep 14, 4:23pm
Yer boot light is stuck on. ?
To check this,put one of your kids in the boot and shut the lid.
brapbrap8, Sep 14, 4:25pm
No real way of knowing without putting a good multimeter on everything to find out what has power when it shouldn't.
Could be the ignition barrel is worn or faulty so isn't turning off everything when the key is turned off.
sterid01, Sep 14, 4:26pm
one fix is to install a isolating switch on the + under the hood .
or go around cleaning plugs and earths and try find something thats on like
stereo , interior lights , boot light , foot lights , key light , rear de fogger thingy , alarm etc
racex, Sep 14, 4:39pm
Any heard about disconnected alarm may still draw current?
clark20, Sep 14, 4:48pm
Batteries can go bad after one year, go to an Auto Electrician, get it properly charged and tested.
ema1, Sep 14, 5:01pm
Glove box light could be staying on when shut or boot lamp staying on. similar thing possibly. If you can't work out what the cause is , take your car to an auto electrician and have hem check what the source of current drain is.
tony9, Sep 14, 5:23pm
This. Alternative test is to open the boot and touch the boot light. If it is hot, then it is on all the time. Same for the glove box.
tgray, Sep 14, 5:26pm
Walk out tonight and look at it with a torch.
tiny15, Sep 14, 5:52pm
possibly corrosion in your alternator
catwoman1974, Sep 14, 5:55pm
I knew someone that had a stuffed battery after 3 mths from new
ruby2014, Sep 15, 5:04am
Do you turn the key to off and remove the key.
If you leave it in accessory position, that could be the cause of the battery going flat.
Go to an auto electrician not a mechanic. The can check batteries better.
bjmh, Sep 15, 5:48am
an old guy told me years ago. gremlins came in the night,they take the amps and leave the volts !
kazbanz, Sep 15, 6:44am
Racex--I'd suggest starting with the very simplest thing. Check the age of the battery. Then check of any lights being still on. -that includes dash lights.
bwg11, Sep 15, 7:19am
Simple things first. Check for current draw with a multi-meter, then systematically remove fuses/breakers until the circuit drawing current is located, then trace the individual component causing the draw.

But as others have said, it could be something very simple like boot or glove box light staying on.

EDIT: Just Spelling
sr2, Sep 15, 7:32am
Spot on advice, we're usually only talking milliamps here so your average multi meter meter in series with the battery will suffice.
captaink, Sep 15, 7:46am
How many times have you found the battery 'flat'. Remember a battery will not keep coming back to life indefinitely, and will do so fewer and fewer times depending on the degree of discharge. take advice as above and take it to someone with a really grunty charger to give it a really good boost. Good luck finding the current draw. I believe batteries are of the feminine gender, 'bloody finicky' unless you treat them real right!
elect70, Sep 15, 1:05pm
I had this with a new nissan bluebird , would do it at irregular intervals & never discovered why even dealers wksp stumped , sold the POS as is once warranty ran out .
danchop, Sep 15, 4:53pm
thought mine was stuffed,but it was the starter motor
socram, Sep 16, 8:37am
LOL. Probably why my 2002 Cooper S is still on its original battery - and I still have the same lovely wife!
yz490, Sep 16, 5:56pm
Had a similar problem with my 2.5 "95 Honda Vigor. Sat for a week though--not over night. Hooked my good ammeter [amp meter] between battery earth terminal & earth lead [don't even think of using the starter the starter! ] then went looking. Ended up being boot lid had been off the catch but barely noticeable as just sits up a fraction till you lift it. Has an electrically activated catch. Other 2.0 Vigor, which has a stuffed battery, will go off the boil overnight so unhook the battery & ok for a week. Only has a fraction of a fraction discharge on a 5 amp scale so assuming it's the clock but might be wrong. Was going to fit an isolating switch somewhere handy & would be a good anti theft device? but then again who would want to nick a Vigor--when i've got a Lada they could have! .
macman26, Jun 20, 12:11pm
Had a Nissan patrol back in the 80's. Just randomly flat battery. Take it in and get it tested nothing ever found. Battery less than 12 months old. After the 4th time and 3 months later I pulled off the vent caps.(can't do that now). Got mate to hold the starter on and lo and behold 1 stuffed cell bubbling. Push started it and put a new battery in that arvo. So even sometimes new batteries can play up and be intermittently faulty.