NemesisUK

I have left my RC300h for up to 21 days without any sign of problem. When you measured the battery drain did you allow the car to fully go to sleep? It can take a significant number of minutes. Also the entry/exit system shuts down to sleep mode after ~10days that basically stops the car listening for the key fob signal. When parked up the 12v battery is only powering the entry system and the alarm

Many marques will recommend maintenance schedules for low mileage cars. The likes of Mercedes will recommend one purchases a trickle charger (at a vastly inflated price over the unbranded version) for their £100k+ cars because they know they will only be driven infrequently.

Not sure you are quoting the correct person?

How many miles over what time and what type of trips have you done in the IS300h?

Lexus recommend turning off the function if expecting icy weather, so there must be an Off position. Have you checked the handbook?

That's the beauty of the hybrid over normal ICE cars. My Mercedes had a Rest function that, with the engine off, it would keep the heater going to keep the car warm. BUT it wouldn't cool the car and even in winter wouldn't dehumidify the recirculated air resulting in badly steamed up windows (ok they cleared very quickly once the engine was started) and the radio would shut down after a short period of time. I can sit for absolutely ages (wife 'just popped' into shops!) in the RC300h car in the Ready state and in Park. The hybrid battery lasts and lasts and eventually the ICE kicks in and recharges it in a matter of moments. 👍

When you say you can't get hold of one in the UK do you mean Lexus dealers can't?

Not a design fault, more a lack of use as designed or lack of maintenance? Have a read of the attached Lexus-tech.eu document. It includes Lexus' recommendations on 12v battery maintenance Maintenance of hybrid battery.pdf

Off

Service

Convalescence

Healey

Limits

Cathedral

Chaucer

Brie

Singularity

How old is the battery?

Coen

Brooks

Dear

Sugar

Square

Diophantus

Lagrange