This may be somewhat of a silly question, but this car is my first hybrid. Are there separate engine & hybrid batteries? If so, when & how should it be replaced? I’m asking because mine is a 2016 & it’s about time for the battery to start acting up whenever it hits 100+ degrees outside.

If the batteries are separate, what’s the correct procedure? I just got an offer from Lexus for $50 off a battery…

 

They are separate. batteries.The hybrid battery aka traction battery is located under the rear seat. The 12v battery is located under the rear storage area floor next to where the spare tire resides. This is only on the hybrids. It is a AGM Battery and costs a bit more than a non-hybrid RX.

 

Awesome! Anyone know if there is special procedure to replace the battery? I read on another thread that folks that got a new battery, fried their infotainment system.

 

Not sure about losing settings and resetting items on the car?

 

Re. the YouTube video showing how to replace the battery.

I noticed that at around 3:35, the guy attached the negative terminal - unsafe practice.

The negative terminal should be attached as the LAST step. This is for safety reasons. Let's say you attach the negative terminal first. Almost every point in the vehicle is negative. Then when you work on the positive terminal, if the wrench in your hand slips, one end still on the bold of the positive post, the other hitting the body of the vehicle, creating a short circuit. Besides other possible damages, you can burn yourself.

Please, gals an guys, negative terminal last.

If you disconnect the battery from the vehicle, work on the negative terminal first.

If you're concern about losing settings (no serious harms done, just annoying), get something like this:

 

I noticed that also, but forgot to come back & point it out. Thanks for doing that.

So, the device you linked to, saves all of your settings before you remove the battery & cut the power? It’s powered off a lighter plug & that would not be working if the battery were disconnected.

 

No, it doesn't save anything. All it does is providing power to the vehicle's memory so that the memory does not lose the contents (settings).

It's powered off another device, say, a 12V power pack such as
(Note: I don't have that particular model, just randomly picked one).

 

You can hook up a charger to the cars cables and then remove all the cables from the battery, with the charger cables still attached to the car cables. The car will still be have input like the battery. Then install the new battery and the cables with the charger still attached. Then remove the charger cables. Just use a trickle charger.

 

Ok, first - 12V is not "engine" battery as it does not start engine. It is power backup for various electronics, when system is turned off. 12V is replaced when its state of charge reaches less than 11.7V. It may be few years, it may be ten years. My OEM Panasonic stayed functional, made in 2006, until few years back and, honestly, I just stopped charging it. So there is not particular time to replace it.
Best practice is to have 12V backup power while replacing 12V. My best suggestion is to use power outlet backup, plenty commercially available inexpensive options. Connecting cables to cables and such is awkward and prone to losing connection.
If you do not provide backup power, you take chance to end with expensive array of error codes that refuse to go away. Depends on you luck.
Hybrid, aka traction battery, is proper "engine" battery as it operates power train. It starts ICE and without it, there is no motive force to the wheels.
When it needs to be replaced? Likely, if you DRIVE your hybrid, never or in VERY long time.

 

Awesome, thanks for the clarification. Since my hybrid is a 2016, I was thinking it may be getting close to time to change batteries. No issues that I’m aware of. I’m glad to hear that both batteries should last a while.

 

I know how to log into diagnostic menu on Highlander Hybrid, but it had Info button. Not sure, how to on RX. Just in case there is Info button, do this:
turn system on to Aux position>press and hold Info button>start flipping light stalk full on/off rapidly>after 3-5 flips, diagnostic menu shows on the display. From that on, you can navigate to all kinds of useful infor and settings, 12V state of charge included.