Gen 2 Prius Lithium Titanate (LTO) conversion

[bravest_bradley]

Hello! This is my first post on the forum. I have a gen 2 prius and I was doing some investigation on the hybrid battery. It uses 28 NIMH 7.2v 6.5AH cells. From what I understand, lithium Titanate is almost exactly double the nominal voltage of the nimh cells. My question is, would this be possible to diy a pack to replace my battery? I've seen some articles about the use of this chemistry written in 2008.
Is there anything out there that would work for this kind of project? Where would I start?
Thanks!

 

[snoobler]

Welcome to the forum.

There is already a Lithium conversion option using 5S LFP blocks. I expect it to fail miserably in terms of longevity due to poor design and implementation; however, it will enjoy a few years of popularity due to the perception of improved performance. This performance improvement will come at the cost of longevity.

Can you? Sure. Almost anything is possible, but to properly do it you need an exceptional skillset that includes fluency in CAN bus communication and the ability to spoof data to the hybrid control computer.

 

[curiouscarbon]

@bravest_bradley welcome to the forums

i really like your idea to use LTO cells in prius. so cool!!

do you have a CAN bus interface or logger? if not i can recommend OBDlink MX+ or OBDlink LX. it relays CAN messages over bluetooth to an ios or android app. be sure to look up what OBD port your prius has to ensure compatibility with accessory plug

i suggest that you try monitoring and reverse engineering the communication on the canbus and become comfortable with how the values and message types change depending on situation

for example, it’s very important to know what messages are sent when the battery is low, when it’s fully charged, when it needs to do this or that or temperature etc.

ensure that the voltage range over the entire 0-100% charge is acceptable. LTO and NIMH might have significantly different voltage droop curves over discharge

consider the situation where your DIY battery disconnects mid drive. what behavior do you expect from the vehicle. the brakes ought to work? just food for thought. make sure you can safely stop if it breaks or disconnects while driving

i think it’s totally possible but the CAN message imitation seems important for success

looking forward to see how your project goes

cheers and good luck

 

[donaldbitterman]

IMO, this is not a worthwhile path. Hybrids (including the beloved Prius (I have a gen 2 as well and love them) are a dead end. If you are going to spend the time/money on a project like this just go all in with a BEV build (maybe an old VW bug conversion.

Keep the thing running for as long as possible. You can rebuild the packs yourself, or there are outfits that do it (I found someone on yelp who did it for ~ 350 and it has held for several years). We are coming to the end of the ICE age, buy as much time as possible with what you have until you go EV.

Not trying to trash your thread BTW, I have played with the same types of ideas and went down the rabbit hole of non like for like replacements for the battery packs.