Lexus GS450H Li-ion PHEV (?)

[Kelju]

I stumbled upon an old 450h with around 375 000km on it.
Got it for cheap as it has (according to the fault codes) a defective aux oil pump of transmission and a single cell block failure of the NiMh battery.
The car is driveable, but goes into some safety shutdown every now and then.
I was planning on trying to replace the battery with Li-ion and include a charger.
Also, it would be great if one could drive 80km/h speed in EV-mode.
Here is a picture from Dr. Prius app. Cell block #5 is weak.

I also took some data logs in the hopes of spotting that lower voltage cell block as a starting point of the can hacking.
I think I need to play back that recording to the OBD Bluetooth dongle and take out messages one by on. This way I'll hopefully see what messages are used by the app (battery data).
Or does somebody already have the 450h battery CAN messages hacked?

[blackjmyntrn]

It's my understanding, you should be able to take out the NiMh cells and replace with Li-ion. Long as you don't go lower in Volts than the original battery is, itll work! Now this is in the Prius world, lots are switching-over to Li-ion.

After upgrading my 2013 Plug-in Prius HV batteries to double the capacity from the factory(I get more EV range than a 2018 Prius Prime) I decided to work on using the factory Li-ion cells in my 2008 Gen 2 Prius! I'm waiting on wire now and hopefully, this should work out nicely for me. Ill let you know how it works.

[rstevens81]

An Interesting and potentially challenging project although i am quite tempted to do similar with an LS600H if they ever become cheap.

By the way I mean none of this in a discouraging way, it is going to be difficult and you are going where no one has gone before but it could be achievable as long as you realise it will take time & frustration but it will be quite a cool project/sofa on wheels:)

As far as i know no one has done any can hacking of the battery so your going to need to get yourself familiar with saavycan (need arduinio due/3.3v can chips also or just get an evtv due), from that your going to have to try and interpret the existing battery so later you can spoof things.

You are going to need to get one of tousle obd toyota modules off fle bay to reset error codes (would recommend an old laptop of virtualbox as software maybe virsused).

Toyota do manual access by subscription, your going to need to grab as many wiring diagrams and manual bits as you can.

The battery connects though a HV dcdc to boost it from 288v upto 650v when used in car mode however it is only rated for 30kw, so your going to need to bypass the HV DCDC (contactor??? to join both sides together) on demand and shut down the DCDC all whilst sending enough can messages to the car doesn't get upset (this is probably be the hardest part!!!) in addition to sending the motor torque compands over serial sync

battery wise (don't worry you wouldn't need it for quite a while ) i would pick an existing phev battery for at least testing that can be broken down into an 80-96s configuration 288v nominal is about 80s for lion battery however if you can get it to work at 96s would be better, based on screen grab at 55% soc its 16.7vx20=334v/3.7=90s so 96s might work ??? i would go with a later 330e battery as thats 96s from 6x16s modules so you go either 96s or 80s depending on what works.
WHATEVER YOU DO DON'T CONNECT A LION TO NIMH IN PARALLEL THINGS WILL GO BOOM CHEMISTRIES ARE TOTALLY DIFFERENT!!!

This is by no means an exhaustive list this is just what comes to mind and tbh you probably want to source a new module for the weak cells so that you can have a working car and mainly as a fall back plan as this is quite a technical challenge that no one has even tried yet and might not even be achievable as there might be too much vehicle integration.

[rstevens81]

I did some thinking and its probably easier to go full ev than its is to go PHEV.
all you have to do to make a full ev is to spoof enough commands that the car thinks its idling so that you can use ac etc.
Then just use zombie to power the gearbox.
Although there allot of technical hacking and general ev building .... a full ev with the gs450h is probably alot easier

[blackjmyntrn]

you know.. the 2013 Prius PHEV... the PHEV system is on its own seperate ECU. I wonder if you could use the PHEV ECU to make your dream a reality.

[Kelju]

Been slowly repairing the car every now and then.
When making a loading test with an electronic load, the NiMh battery turned out having 7 defective modules out of the total of 40. I managed to get some (9pcs) replacements and redid the test. I balanced all modules (over night) to the same voltage first and then made a load test. Here you can see the combined result of all remaining original modules (33pcs) and the replacements (9pcs). Two of the replacements are bad, but luckily I had 40pcs "relatively" equal quality modules, i.e. just enough for the full pack. The odd looking spikes are induced by my DIY measurement setup.

Next item to fix was the transmission oil pump. The most common failure in these is seized bearings, so I dismantled the unit only to find out that the bearings where not that bad. Replaces the bearings anyway, but the pump was still not working. Apparently the problem is in the rotor position sensors. All HAL sensor lines are sitting at 5V all the time. Might try to repair the internal PCB at a later time, but at this point I purchased a replacement pump and finally got the pump related DTC erased. After this, there was still the issue of fixing the rear brake lines that where rotten through and leaking brake fluid.
After all of this, I finally got working car and actually passed the MOT today.

I feel like I've been working on the car for quite along time already. Now I finally have a working car that I can start reverse engineering.

[j2digital]

This may be something I am interested in as well! I also picked up a gs450h with high mileage (360,000+ miles) for dirt cheap with the idea that I'd gamble on at least parts of it being salvageable for my EV swap. Turns out it starts up just like any other Toyota wants to (after I swapped out the 12v battery). The only check engine light is for the catalytic converter and I've driven it probably 200 miles. The possibility of swapping out its NiMh for Li-ion to boost its hybrid range would be awesome! Even more awesome if we could use it in "EV mode" for a while before plugging it in or going back into hybrid mode. Sorry I can't be more than encouragement ATM but I do think it's a cool idea! Good luck man! If I gain any amount of useful knowledge or experience I'll try to help if I can.