Thanks for your inputs guys. My answers below are interspersed.
Originally Posted by shonty
Maybe you left any of the lights ON or the battery just needs replacement.
Nope, I am pretty confident nothing was left on.
Originally Posted by ilango[speed thirst]
That is the end of battery life. thank it for serving you so well and gift your car a new one.
also note, it must be almost time for the change of the tyres too. OE batt and tyres are crap!
Yeh I guess so. I will have it checked and update. About the tyres, The stock tyres lasted me 39K km without a single puncture throughout but handling took a hit due to wear and tear and then I changed to Yoko A drives.
Originally Posted by shailinder
Did you check the water level of your battery by any chance ? Ideally you should get some signals like lights are getting dim during idling or lately during cranking your engine it is shaking a little before coming into life or something.
As suggested above, battery life generally is 2-3 years and it is time now to get it changed. Even if you want to continue with it. You have to keep a constant watch on battery water level and signals you get.
All the best.
I had no indication of battery down. Never was a time I had to do a full crnak to start the car. What puzzles me is just 2 days of idle killed it. Even now, when I open the doors, teh cabin light is fully lit but when I crank. There is no crank and the power drops completely. Horn sounds very faint and meek too
Originally Posted by freakdude
As everyone has suggested, it's almost a good time to let go of the battery as it is nearing it's end of life. Although battery might go a bit more if taken proper care of. You can do a self diagnose too. Open the battery tops to see if all cells have enough electrolyte in them. Alternatively, take the battery to the battery shop and get it charged. Fit it back in your car and take it to an experienced electrician to get it checked for any electrical leakages (since it got drained when parked for 2 days, so, no alternator support). Just curious, do you have any battery exhaustive add-ons in your car??
I have a suspicion that the elecrolyte levels may be down. I have never opened it to check and refill over the past 2 and half year. My car is regulary serviced at the A.S.S and I presume they would have it in the check list. Howver I feel this could have been an overlook. Coming to add-ons the only add ons I have is My Car Audio - with an Amp and a Subwoofer with 4 components. I use it very sparingly. There's couple of LED strips running under the body.
I had however installed Autocop keyless entry a couple of months back. Would this be a drainer ?
I'm going to check the electrolyte levels in a short while and keep you posted.