It is seven years old and measures about 12.1V, so I think it may be time to replace it. Worth trying to desulphate it?

But basically looking for some guidance on the auxiliary battery replacement. It appears to be different from the 450h models probably because of the 3rd row seating. it is rotated 90 degrees and very close the rear quarter panel.

Two questions:

1) Will a size 47 fit? Or should I go with the 35?

2) How to undo the nut that holds the bracket down, it is not accessible easily compared to the 450h in videos I have seen.

Thanks!

 

The RX350 use group size battery 24F.

 

He does not have an RX 350 he has an RX 450 and that is quite a difference when it comes to parts. He could easily call his local dealer service dept. and ask them for the correct size. It could very well be a 24F.

 

You are right. He should have posted in the Hybrid section.

But anyways to answer the OP's question, it calls for Group 47.

https://costco.interstatebatteries.c...option=2463394

 

I did not realize there was a hybrid sub-forum. Will ask there. Thank you!

 

Here are some pictures of the battery

 

You've likely solved this problem but wanted to post here in case anyone from the future decides to search.

The 450hL 12V battery is not commonly available at most auto parts stores (Auto Zone, O'Reilly's, Napa, Costco, etc.). You'll likely have to go to Lexus to get a replacement battery because it's a special Japanese format. If you're in a bind (middle of nowhere) and a normal H5 AGM is your only hope, I'm sure the electronics will work--it's just that the H5 won't fit nicely back into the rear corner without rattling and/or cutting some of the bottom bracket. The vent tubes from a 450hL also don't fit an H5 AGM battery.

The 450h does use an H5 AGM but I think the 3rd row seats require a smaller battery in the 450hL.

 

Thanks for your response. I wound up with a slightly larger battery that has more power. It did not quite fit, so I had to make some adjustments to the bracket that held it in place. Yes, had to use a largish hammer to bend the metal into the size it needed it to be.

Went to ACE and got a barb that fit into the battery I bought. Sealed the sides with some silicone.

But it works so I'm going to leave it alone for the next 5 years or so and make any adjustments that I need to at that time.

 

Your decision helps me, bc I have a same situation for battery replacement of my 2018 Lexus RX450HL.
I like to know exactly what battery you replaced and how you did connect the vent hose to the new battery.
Thanks in advance for your useful information.

 

Yeah, the L model battery setup is definitely tighter. You'll want the Group 35 battery, not the 47. The 47 is for the standard length RX. For that nut, a small socket wrench with a universal joint or a flex-head ratchet is your best bet to get in there at an angle.