Apparently my alarm was going off for a few hours today in my '08 IS250. By the time I get to it, the alarm was very weak and quiet and the lights were just barely flashing. I had to get into the car manually as the FOB wasn't able to communicate. I hit the ON button and get nothing. No dash lights, no response, alarm still going off. I'm about 7 hours from home at a hotel in the middle of nowhere, so I call Lexus Roadside Assistance to get a jump. The guy wants to walk me through a few steps to make sure the car won't respond in any way. He has me get in the car again and asks if I hear a rapid clicking sound. I tell him no, so he has me hit the ON button. I tell him I get no response, so he says he'll send someone my way. As I'm giving him my information, I'm continuing to hit the ON button with the clutch engaged just trying to get the damn alarm to shut off some way. Eventually, I kill the battery all the way by doing this, and the alarm stops. I'm still talking to him and about 30 seconds later I hear the rapid clicking under the dash that he was talking about. He says, "Ok, good, that clicking sound is the battery trying to recharge itself."

...... What??

 

lol, not exactly...

In truth, a battery when left alone will regenerate a small amount of its power... It is an electro-chemical device after all. May not be enough for any high current demands, but it will try to recover...
I'm sure someone here can give you the science of it...

V

 

I was holding back a laugh haha. I've had them go from totally dead to maybe getting half a crank on my older cars, but on something with all the electronics of this thing there's no way. And that's definitely not what that clicking noise is haha. Oh well, he sent Triple A my way at least.

I had to call a friend make sure we hadn't discovered a way to make electricity just appear.

 

That clicking noise is actually the sound of your Lexus communicating with aliens from Vega via morse code, who upon receiving the distress call begin transmitting energy to the battery wirelessly, but through a wormhole (because the speed of light isn't fast enough). That's why there's a small delay, opening the wormhole takes approximately 30 seconds to complete.

 

I knew it had to be something like that.