Yesterday I get into my car to find that it's dead. The instroemtn panel would have difficulty lighting up but the engine wouldnt even crank.

I called Lexus roadside, they came to jump my car, I then drove it for 20 minutes, let it sit for another 20 before and after the drive, so the car was on for about an hour. Hoping to recharge the battery.

Today I get it, and once again, it's dead. Had to have the car jumped to start it again. When they ran tests they said the battery is fine but the altinotor is running at 13.90 insted of 14V. According to them it shouldnt be a issue?

What could be the problem?!

And no..I did not leave any lights or anything on, just simply locked the car. (Remote lock/unlock still worked btw)

Are you still on OEM Lexus battery? If you are, check the battery's fluid. There should be an indicator on the battery itself to tell you the health of the battery and instructions on what to do as well. If fluids are low, make sure you use distilled water to fill it up NOT TAP WATER!

If that doesn't fix it, take it to a shop to have the alternator checked.

Sound like me 2 weeks ago. Take it to the dealer and let them test the battery. If you're not under warranty anymore.. take it to autozone and let them test it. They will test your battery for free. AAA said my battery was ok but Lexus checked it and said it was bad. It failed the load test. They replaced it for free under warranty. Good luck.

You need to have the battery load tested.

You can do a crude version of this by fully charging the battery with a charger, turning the car on (double push) without starting the engine, turning the high beam headlights on and leaving the car for 15 minutes in that state. If the car fails to start after 15 mins of drain, despite an overnight charge, the battery is toast.

Just a quick tip when looking for new battery. My IS has a Japanese size battery, not a us or euro size battery. Every single garage or parts supplier I checked lists the WRONG battery for my car. The recommended batteries will not fit. I had to find a parts supplier that sells j-size batteries (matched to the part number on my battery) and even then they didn't want to sell it because "it wouldn't fit". (it was a perfect fit, by the way).

Sounds like me. Recently replaced my battery. Had Toyota order one from Lexus. Cost about 110, and I installed it myself. Those clips on the side are pita . Good luck !

I would go to advance auto/autozone somewhere like that and have them test the battery to see if its capable of holding a charge. Depending on how old it is it might be time to replace it.

Check both ends of your ground, battery and other end, make sure you have an excellent connection. If you have a loose ground battery won't charge. 13.9 on the alternator should be fine.

Machog

Replace it with Gold Top 24-DLG battery from Autozone, $110, 3 year warranty, DONE. No need to repeatedly getting stranded with a dead battery, replace it and get on with life.

make sure you got a clean good connection and how old is the battery?

The magic eye on the battery only shows you the condition in just one of the six cells -- I wouldn't trust it. Speaking as some one that still has the OEM battery in a car that was purchased in early December 2005, I check the electrolyte yearly and generally have to add a bit of distilled water each year.

I'm not sure if the battery is from the factory..It has a sticker on it of 12/10 and the battery says "Lexus on it" with a 84 month warranty. And I couldn't seem to find any indicator as the sticker covers most of the battery.

In that case if the battery is defective it will be replaced for free by Lexus, but you'll have to go to a Lexus dealer to have them analyze what is going on and to see if the battery is defective.

Simply your battery. Time to replace it.