My car is the 2014 Lexus IS250.

Replaced my car battery in November 2017 (as the car couldn't start).

Battery specification:
CCA: 447
AH: 60
RC: 108

My car was running well, drove about 100 miles last week. Last weekend, car refuses to start, cranking sounds can be heard, but engine wouldn't start. Used my other car to jump start it.

Next morning, drove to the battery shop, they tested the battery, and they say, it is fine and probably it's the car's fault.

Now, I've tried googling this issue. From dim lights (not sure if 3IS light can dim) to smells from the engine bay. I cant seem to know whether it is the battery or it is the alternator failing.

Please help.

 

I had the same issue. autozone said it was good. I bought a new battery anyways. and now 5 months later its still going strong

 

My battery shop didnt want to replace the battery for me.

 

If you can check the voltage when the car is running and it's over ~12.3V then your alternator is most likely good.

​​​​​

 

When engine is off, should it be 12V?

Then when it is running, over 12.3V?

Would you or anyone be able to advise what's the Voltage for:
Engine off (24 hours of idle): XX V
Engine off (2 hours of idle): XX V
Engine running: XX V
Engine off (straight after running): XX V

That would help me greatly

 

From service manual:
After running the car for a while (after a drive should be suffice)
Check the voltage.
(1) Turn the engine switch off and turn on the headlights for 20 to 30 seconds. This will remove the surface charge from the battery.
(2) Measure the battery voltage according to the value(s) in the table below.
Standard Voltage:
TESTER CONNECTION CONDITION SPECIFIED CONDITION
20°C (68°F) 12.6 to 12.8 V

Do you have blind spot monitoring? There's a big thread about parasitic drain with the gateway module.

 

No Blindspot monitoring equipped for my car

 

Your car is a 2014. Did you ever get the gateway ECU looked at?

Please check out this thread
https://www.clublexus.com/forums/is-...hlight=battery

 

yes, dealer said, nothing is wrong with the gateway ECU.

 

my dealer said the same thing too. do you have the updated ECU? you should insist on them replacing it with the updated part.

 

My readings this morning



The Voltage for:
Engine off (24 hours of idle): 12.55 V
Engine off (2 hours of idle): 12.66 V
Engine running: 13.5 V
Engine off (straight after running): 12.7 V

Any feedback is helpful

 

My 14 leaves me stranded if I don't drive it within 24hrs. New battery, dealer tested said all is good but it is not. I don't have bsm either. ****ing joke.

 

anything aftermarket installed? have you done a parasitic drain test?
I had a battery issue, and it was my remote start antenna that was draining the battery.

 

I would like to see the aternator voltage at minimum 13.8V to be charging the battery effectively. Ideal is around 14.2V.
To test the alternator properly, turn on all accessories: Lights, radio, AC. Leave on for a few minutes.
Have someone rev the engine to 2k rpm and observe the voltage. It should fluctuate between 13.5V and 14.5V. If the voltage stays the same or is dropping, then you may have a bad alternator.

 

Tested again this morning, cold start (after 48 hours of idle)

The Voltage for:
Engine off (60 hours of idle): 12.41 V
Engine running: 13.66 V
Engine running: 13.86 V (with Revs)
Engine off (straight after running): 12.63 V

Any feedback is helpful