riredale

No, not related to each other. Brand-new owner of a 2010 450h. This morning I was curious about the holding power of the parking brake (the one on my old Mercury Mountaineer was a bit of a joke) so I gently applied the foot pedal while moving about 1mph. Wham! The car stopped as though it hit a brick wall. So I wondered, is this brake a friction device or some sort of locking device?

Regarding the 12v battery, I understand that it is in charge of everything except for the big Nimh pack that powers the drive motors. So does this mean the 12v battery also handles steering, brakes, and A/C? The reason I am curious is because I would assume that, for example, the A/C requires a major load on the electrical system. Maybe a deep-discharge battery (as for boats) would make more sense than a "starting" battery that can't discharge very far but can provide a gigantic current flow for a few seconds.

Oh, and I suspect that using 87 gas in this car will reduce mpg's by a few percent but otherwise make little difference to this Atkinson-cycle engine. Yes?

Anyway, love the car

vlad_a

Welcome to the forum!
There's nothing special about the parking brake, other than it having its own dedicated drum and shoes.
A cable connected to the pedal pulls the shoes apart, which in turn create friction.
That's a pretty standard implementation for rear disk brake systems.
This functionality is shared when only drum brakes are used in the back.
Latter self-adjusts with each parking-brake pull to compensate for wear.
Former does not and may need a manual adjustment over time.

I used to engage PB all the time on our RXh... until I found one of them stuck in the middle of a road trip.
I was able to let it loose and no problem was found by a tech later on. I only engage it on inclines now and check wheel temp when driving on long distances.
Our parking brakes are prone to get locked after a car wash.

12V battery is used for the same type of operation as in a conventional vehicle. No, it does not power the AC, traction battery does.
All main ECUs are indeed 12V, which is why the RXh needs a boost to start if the battery is low.
Once it is "started", 12V power is supplied via a DC-DC (DC-AC-DC?) converter. Engine does not need to be spinning for this.

I also noticed degraded performance and MPG when running 87 gas.
I'm not sure what the story is with Lexus rating same engines for 91 when Toyota counterparts are rated for 87.
Is it only to achieve better power and mileage figures, or is there a different tuning?
There's a huge MPG thread that you can subscribe to for detailed information.