Car has intermittent starting problems as if it has a dead battery. No dash lights while running.
backstory - a few weeks ago while sitting with the engine off in accessory mode with the HU & radio on after about an hour of this the engine wouldn't start - steering wheel shuddered when it presented itself, starter ticked. I got a jump, spent a couple hours on the highway & about 1,500rpm while driving around town. Had the battery and charging system checked, everything is fine.
mind you thanks to covid I'm hardly driving, maybe a few miles around town each day. Didn't happen for weeks, today my BIL who is watching our 6yo son while we are in the hospital having just had our second on the 24th, has the same issue. Thankfully he has a car and moved my sons seat into it.
At this point I'm going to jump it again when we get home & I'll probably replace the battery out of piece of mind as it is the original 2015 battery.
terminals are clean, connections are tight. I don't think my son left the rear dome light on, but he has before.

I Will be able to assess better when I get home today, but if any of you have any thoughts in the mean time please post them.
Happy Thanksgiving!

 

I would say at this point the battery is the most likely cause.
If your vehicle is a 2014 production for 2015 model year, then the battery is probably just about 6 years old, or older.
You have definitely gotten the life out of the battery and then some.
If you've had no other issues, I would feel confident a new battery will resolve the issue.

 

Why are you sitting in accessory mode with the radio on for an hour? Of course you’re draining your battery when you do that. If you have to sit that long just run the engine, or shut off the car and listen to something on your phone. If your engine is not running, your battery is not being charged, and this all gets worse the older the battery is.

 

Definitely the battery. I just replaced mine on my 2016. When it died the first time after a day of not driving, after jumping, it would die within 15 minutes of engine off.

 

My 2015 with original Panasonic battery from factory just died today. 5-6 years on a battery isn’t to bad at all.

 

My battery tested weak when I had a tire repaired, on my 16. I replaced it soon thereafter.

 

what battery brand do you recommend for us in Ontario? My understanding is there is only 3-4 manufacturers of batteries and retailers simply rebrand them.
Where should I go? Canadian tire has a “Motomaster eliminator AGM” for $233 its a rebranded East Penn Manufacturing comes with 5 year warranty....
Costco has “Kirkland signature series” for $129.99 with 4 year warranty I don’t know who actually makes the battery though.

 

I used the OEM in my Lexus when the battery was replaced, comes with an 84 month (7 Year) warranty.
All battery warranties will be pro-rated...if it fails before end of warranty, you pay the difference on years used vs years left.
I'm pretty sure the batteries Toyota uses in Ontario come from East Penn...it's a direct to dealer item, meaning when they order it the battery doesn't come from a Toyota parts depot, but directly from the manufacturer.

 

To the "why ACC mode" comment my son and I were waiting for a drive-through covid test - he had my phone and was playing games on it. I try to have as minimal an impact on the environment as reasonable, so I don't like to idle if I can avoid it. Prior vehicles have had no issues starting after running the radio for an hour+, even vehicles still on the original battery (my FIL's 07 Frontier, my wife's former 07 yaris & my former 06 wrx wagon to name a few). The Lexus just has more of a draw due to more electronic stuff (steering wheel presenting itself, auto headlights & HU screen for example). Replaced the battery, started fine, let the HU/system boot & I'm confident it will be fine now.

 

Can someone plz help...what friggin size does a 2015 Lexus is350 take?
Group size 24? 24F? 35?
Can’t find a clear answer...I bought a group size 24F and polarity is wrong but everything I see says that’s the right size...
can someone plz help!

 

The IS takes a Group 24 battery...if you bought a 24F and the poles are reversed, then you need the regular 24.

 

group 24 will have the correct poles - I bought a 700CCA model, stock is 580CCA. New England winters and all that.

 

im in Canada, OEM from dealership is 169.99+tax=$192.10
not seeing very many other options, wanted to get something with lots of CAA as it hits -40 Celsius where I live.

 

If the OEM battery lasted 5-6 years and served you well doing that time, then it seems like a good candidate for the replacement.
While more CCA is nice, at what point is enough, enough.
If OEM is 580CCA, that's pretty good already...700 is cool, but we're not trying to start a diesel engine, let's be honest.
Plus anything bigger and better then gets into possibly modding the battery tray and/or hold-down.
And if you can find an aftermarket one with a 7 year warranty, I'd be surprised.

 

I’m worried about those super cold Ottawa winters, plus working from home she does sit a lot.
OEM is Panasonic from factory in Japan but dealers sell a rebranded generic from exise or Johnson I think...plus it’s 2 year replacement warranty 5 years pro rated...AND they have to install for $50 plus tax or u get no warranty...so dealer is $220+tax...I’m just gonna grab a motomaster eliminator from crappy tire as Costco does not carry group 24...only 24F.
Crappy tire is $135, 3 year replacement warranty.