Something is eating my battery

[Steve Graham]

I left my car for 4 days and on my return, the 2-year-old Battery was completely flat. Rapid charging for a few minutes allowed the car to start and drive.

When I got home, I put my multimeter in series with the Battery, and with the car turned off, I found a drain of around 350 milliamps. I haven't had a chance to exhaustively test everything yet, but I did find that when I removed the fuse labelled "HAZ", the current fell to a much more expected value, around 50 mA.

"HAZ" as you might guess, protects the indicators and hazard warning flashing. The odd thing is that when I put the fuse back in, the excessive current drain didn't come back immediately. I re-tested some time later, however, and found it back up to 350 mA. I can't remember if I did anything significant in the interim.

When you pull the HAZ fuse, the car beeps several times. I don't know why this fuse alone has that effect.

Obviously, I've checked for cabin lights, lighter sockets etc! Any ideas?

[craggle]

Not sure what size Battery you have but assume it's a reasonably large one, 70ah Battery perhaps?

So if you were drawing 1 amp from the Battery it would be flat in 70 hours but as you are only drawing 0.35 amps I think it will take 200 hours to completely drain the battery. 
Might be worth getting the battery load tested and the charging circuit tested to make sure that is all up to speed. I have seen car batteries fail when only a year old so age isn't always a good guide.

I used to own a Range Rover and that had an issue that the key fob worked on a similar frequency to wireless door bells and wireless routers. If I left it parked close to certain buildings the signal would wake the vehicle up as it thought you were nearby with the key but it didn't unlock the doors. You could watch the battery drain going up and down as the vehicle went to sleep then press the door bell and up the load went again. I was told once that airport radars can have a similar effect?

Have you parked there before?

Craig.

[mickburkesnr]

What brand of Battery did you get, and what was the warranty given with it?

Sometimes a cheap Battery can let go alot sooner than you'd think. I wouldn't think a 350mA current would drain a Battery like that in 4 days to be honest. 

[Steve Graham]

The current drain is definitely about ten times what it should be. (At all times, remote from wireless sources -- good suggestion though!) The standard capacity for a petrol RAV4.2 Battery is just 45 Ah so although it's a decent make and not too old, it would be totally discharged in 5 days.

The alternator etc. is working fine, since the Battery does get fully recharged when driving. 

I'll have time tomorrow to investigate further.

[alan333]

I'm not familiar with your particular car, but the hazards should be a different fuse to the indicators, since the hazards are live with the ignition off but the indicators require the ignition on.  The haz fuse might cover other things which are live with the ignition off, like perhaps the interior lights and cig lighter (as you already mentioned), and maybe even the alarm (which might explain your beeps)?

[IanML]

The Turn Signal Flasher Relay is supplied by the 10A HAZ fuse and also has a feed from the 10A ECU IG fuse, which explains how it caters for the above conditions.

There must be a partial short to earth somewhere is the wiring.  I suggest progressive disconnection to find the spot.