My 2nd battery is no longer holding a charge overnight. Same thing happened 2 years ago, Lexus said my ECU was fine and replaced the battery. Now same issue. Just wondering if 2 year battery life is normal on this car or should I investigate more? Thanks.

 

I had 2 batteries replaced in 4 years so yeah...not that uncommon.

 

2-3 years is about the average life of a OEM battery from owning lexus vehicles the last 10 years. I started to replace them with the costco/Sam's club battery's that last longer.

 

I still have my factory battery when I bought the vehicle new in 2014, I only have 25k miles though. I probably need to replace it soon.

 

Still on my OEM battery from 2014, purchased March 2014. Once every winter for the past 3 years I have a dead battery in the winter but it only occurs once. I charge it up and it repeats next year, I can handle the once a year inconvenience though

 

Battery life is really subjective to use and climate.
Around me, getting 5 years (give or take a year) out of a battery is pretty much the norm.
The heat really kills the batteries more than anything else that is constant.
You may find that a climate like Florida the battery might only last 2-3 years.
Then there's the actual usage of the vehicle to factor in.
The dealer replaced the battery in my 2014 in 2016...at that point it was 2 years and 10 months old...but the battery was fine. They just replaced it cause.
I've had that battery since then...now over 3 years later and no indications that it's nearing the end of it's life..,still going strong as ever.

To the OP...does you IS have Blind Spot Monitoring or Clearance Sonar?

 

Still on original battery after 4+ years of NE winters. If you are replacing batteries often, have a mechanic test the charging system and for overnight parasitic drain.

 

engine-mounted 4-5 years. standard.

trunk mounted, passenger compartment mounted, etc., 8-10+ years. bmws have been known to go 10+ years on the original. but heat kills smaller batteries in the engine bay. still though, on ANY car, i wouldn't go past 5 years unless you really don't mind getting stranded.

 

But you have to factor in overall cost as well.
A Lexus dealer battery is probably around $200 for the part, and then the labor to change it...let's say 1 hr, so about $120 (I'm guessing on what labor is)...and the battery will last 5 years, let's just say 4 years for sake of argument.
German OEM battery that is mounted inside the vehicle is usually much larger, hence much heavier, and due to construction, will cost about $400 for the part, plus the additional labor to change a battery that's inside the vehicle (so more than $120), plus the reprogramming cost associated with the battery being disconnected (whatever that labor is...likely at least another $120).
The Battery has to be programmed to the vehicle, and the other computers on board have to be reprogrammed. I'm gonna guess the install and programming labor is as much, or more, than the battery...which is average $400...and could cost more in some cases.
So even if you got 8-10 years out of a German internally mounted battery, by total cost comparison, it's still cheaper to replace your Lexus battery twice, maybe even 3 times, before you change a German battery...and that's providing you get at least 8 years out of the German battery.

And hopefully in either case no one gets stranded and usually the vehicle starts to show warning signs of a battery that's at the end of it's life...i.e. slow cranking
At least with a Lexus you are a battery boost and trip to the dealer away from being back on the road.
With a German car you are likely a tow truck ride away from a dealer and a battery replacement/programming before you're back on the road.

 

BMW also use AGM batteries to support its mild hybrid system. The extra cost pays for better mpg. You can also get the battery programmed for much cheaper at local mechanics.