Majek

I just replaced my OEM 12V battery on a 2007 GS450h. It was the original battery dated from 2007 so after 9 years it deteriorated to the point it would not hold charge after 2 days of sitting and require a boost. Our original battery is a Panasonic S65D26L AGM located in the trunk. I replaced this with an Optima Yellowtop SC35DA D35 AGM deep cycle battery which is a direct fit since the OEM battery was far too expensive at the dealer. You should always replace with an AGM battery and other brands/models should work.

I taped off the end of the vent hose so nothing gets in. The temperature sensor was taped on the side. The battery came with a yellow bracket that I placed under. The only concern here is that the vent hose is no longer being used so the battery has to vent in the trunk. However, if you read up on AGM technology you will see that it is a sealed battery and venting only occurs in case of rare overcharging. You may disagree and insist on having a vent hole by purchasing a new OEM battery.

REMOVING OLD BATTERY
1. Remove fuse clip from metal bracket
2. Remove vent hose from elbow
2. Remove temperature sensor wiring clip and the actual sensor which is under the top label of the old battery held together with glue. Pull it slighty and it will slide away from under the glue
3. Unscrew and remove metal bracket holding battery
4. Remove negative lead from terminal first and then positive lead
5. Lift and remove battery

INSTALLING NEW BATTERY
1. Place battery in holder
2. Screw metal bracket
3. Install the fuse clip to metal bracket
4. Tape off end of vent hose
5. Tape temperature sensor to side as shown in picture
6. Connect positive lead to terminal first and then the negative lead

RESULTS
1. Car started up right away without any error messages even though the car was without 12V power during installation.
2. Only settings I had to do so far was the window/sunroof initialization (see manual) and change units from miles to km. Everything else seems to be retained.
3. I have driven almost 100km on highway and city since installation. Hybrid battery charges fine and MPG seems to be improved but I'll have to look further.
4. You can monitor your current battery voltage by going into diagnostic mode (hold INFO button and flip headlights on and off 3 times). I need to do further testing to see how the voltages hold after hours or days of sitting with this new Optima battery. AGM batteries hold charge longer than regular lead acid batteries.

Good luck!

Pictures of NEW VS OLD with labels:

Drift King

I did the same thing a year ago without issue... =)

LovezLexus

Wow great post! How much did this end up costing you?

Drift King

I paid $205 at Sam's Club for mine... Sure beats the $600 Lexus wanted for the Panasonic battery! =)

Majek

I paid $250 for mine. I did a resting battery voltage measurement with the new battery. After 18 hours of the car just sitting, I turned on the accessories (without turning on engine) and went into diagnostic mode (hold INFO button and flip headlights on and off 3 times) and the voltage was 12.6V.

Drift King, have you done a similar test?

bolido

I tried using the Optima yellow top, but the battery just wouldn't hold the charge if the car sat for more than 2 days. Also, when the battery was charged, the start up of the engine felt much "rougher". I ended up getting the OEM Panasonic after 2 weeks, and I think it was around $350-400. Just FYI for anyone thinking of using the Optima.

Majek

It's possible you had a defective battery or another issue. I tested mine again over the weekend. After about 60hrs (2.5 days) of the car sitting, I checked my voltage and it was 12.5V.

dayjob3

Love these little tricks. Keep-em coming.

KoSC300

I used the same Optima battery shown here and like bolido, the Optima would only hold a charge for 2-3days. I then went with a Kirkland #3 battery and it seems to hold a charge longer than the Optima, 4-6days. But still not long enough. Not sure what the issue is. I'll try the voltage test you guys mentioned.

Drift King

Forgot all about this post till the bump... I had to find the right menu to check the voltage, but mine reads 12.7-12.8V. Over a year and a half and no issues. I wonder why it is not working for some of you... A battery, is a battery, after all.

Majek

That's strange. Sounds like something else is draining the battery. I've left the car sitting outside for 2+ weeks at a time and it read about 11.2V after firing it up during this cold and snowy winter months. The battery has been working great since I installed it.

energie8

I searched on a few sites for batteries and even on optima/interstate sites for 08 GS450h but it says non compatible, I recently bought a battery for my 06 GS300, would it fit over on my 450h?

Cashish

Probably not. As mentioned before, the OEM battery has a port for the vent tube to vent gases externally.

Nikoloz

Hello folks, would anyone have any ideas to where may i buy the temperature sensor shown in pictures? Got gs450h 2008 myself and the sensor is missing with P0517 code. I am pretty sure it is the reason. I tried many places to look up the parts but google search gives me nothing for "battery heat sensor lexus gs450h" in many variations. Please help.
Thank you.

Swaganomic

For anyone reading this in the future, I did the same installation on a 2011 G450H. I got an Optima YellowTop D35 swapped for the OEM 12V and seems to be working fine so far. It's only been two days, but I'm driving constantly due to Uber Eats, errands, visiting people, etc. and have had zero issues so far. In fact, startup seems to have improved. Will try to update if changes for the worse in the long run. Installation went fine. The battery itself is shorter in height than OEM, but it comes with a spacer that makes it perfectly compatible with the original tray and bracket. Only other thing is the lack of a vent tube (which isn't needed anyway), and having to remove the temperature sensor from previous battery, which is easy to do (literally peel it off old battery, and tape it onto new). I got it from Autozone for same day pickup at $289.

AMZ: Autozone: https://www.autozone.com/batteries-s...d35/605893_0_0