Is300 won't start - continuous problem

[Vincento]

We have a '19 reg is300. It only gets used at weekends as we WFH or commute by train.  So far this year it has failed to start on 6 weekends out of 9.  The dealership say the Battery is fine and we should expect this from a hybrid.  I find that hard to believe. Our last car was an early Prius with a similar weekend only pattern of use and it was fine. Can anyone advise if this is normal for a Lexus? 

[ColinBarber]

It isn't normal but just sounds like you never full charge up the Battery so discharges too much before you use it again and cannot start, and if you get cycling like that it will get worse and worse until you need a new one.

A fully charged Battery should last 3 weeks without the vehicle being used.

[cruisermark]

Perhaps its the keyless entry that it using the Battery - it might be an an idea to run that off?

[ColinBarber]

1 hour ago, cruisermark said:

Perhaps its the keyless entry that it using the battery - it might be an an idea to run that off?

It will help but it should still be ok for three weeks with it enabled, and that system goes into various power save modes after a few days of being left alone.

[m4rkw]

It could simply be that you're not driving it enough to charge the Battery, do you do a lot of very short trips on the weekends? On most cars the Battery subsidises the alternator at an idle, you need to drive it for a while to get the Battery to charge. This probably varies from car to car but I'm told it's more significant on newer ones.

Or it could be something is actually wrong, like a parasitic draw. There are probably videos on how to check for this one youtube, just be careful to find one that's hybrid specific (I don't know much about hybrids), there's probably stuff that's unique to them that you need to watch out for.