LiFePo4 traction battery replacement ?

Why? The benefits of LiFePO4 are in energy density and more deep cycling. Toyota purposefully doesn't discharge the battery pack very much and keeps it between 40% and 80% naturally so the deep cycling becomes moot.

The cost between LiFePO4 and NiMH is pretty large and in the non-Plug-In Prius, it doesn't matter much. There have been experiments with doubling, tripling, and more the traction pack. No benefit in fuel economy with the added cost of extra weight and even suspension modifications.

Where lithium makes sense, is in storing grid energy for all EV us. And yes this has been done! Hymotion was a big one back in the day. So there are packs that exist for GenII Prii that are all LiFePO4 and work. But you won't get any benefit from it unless you add a plug.

 

Well if that's your goal, then some standard LiFePO4 cells to about the same pack capacity would yield a good amount of space inside the pack to do all the other electronics.

The Prius pack works on a large range of voltages because the NiMH cells go up and down like crazy under loads. LiFePO4's are pretty stable. So you really only need a BMS charger and a BMS spoofer for the easiest "transplant". If you wanted to go crazy with EV modes and charging and all that, then you need to fool a lot more computers and turn off the gas line and all that.

You will need to control the state of the LiFePO4's independently of the Prius control.

Definitely possible.

 

This has been done.
It is not any less expensive than Nimh. You have to fool the car in so many other ways to be able to do this. Software, CAN interface, charging, etc. Plus you'd be constantly be tinkering with it.

I could sell you a really nice set of batteries that you could use if you are interested in making it though.

 

Yes it can be done. I'll be doing it on another gen 2 soon. No charger for this one, it will just be meant to replace the nicklemetal modules. I may not even use a BMS this time.

XT1585 ?

 

keep in mind, enginer went out of business, because their product was unreliable, and it was too expensive to make it reliable.

 

we understand that. unfortunately, they would not be drop in replacements. your in for more work than you realize, not to be negative, just realistic. there's a reason it hasn't been done. i wish you all the best.

 

You will need something between the normal battery input and the new lithium pack. The NiMH voltages are not compatible at all with what a LiFePO4 pack will want. The Prius just blasts the pack with high voltage when it wants to charge, and that is perfectly OK with NiMH. But with LiFePO4, they go boom when you do that. You need to convert the big high voltage charge into a lower voltage higher constant current.

 

the way i look at these projects, if you have to ask, it can't be done. now tony isn't asking, so who knows what he's got up his sleeve.
when sparky built his plug in prius a few years back, no matter how much he tried to explain, no one else could understand. that's a huge knowledge/capability gap.

 

You can make it as simple or complex as you want. But often simplicity also affects safety.
I'd you really are considering this project I have blocks of ~20 ah A123 26650 cells. Bigger capacity than the original battery but would be fun nonetheless. Probably cost you around $3,000 for cells and associated wiring

 

The C rate of Lithium is much better than the Nicklemetal batteries. They won't go boom, lol.

XT1585 ?

 

why would someone pay $3,000. for parts, when they can get a brand spankin' new toyota battery for $2,000.?

 

Putting in lithium is not about trying to save money.
For the fun of it. Just like getting cool rims or a different stereo.
In this case it would be a higher capacity battery.
These 13.2v modules are ready to be wired up.

 

We have a couple recent threads of interest...if I understand Grus quotes roughly $1500 for Prius Gen3 NiMH batt from the manufacturer in Japan (PEVE) whereas the sister Li Prius version (used in EU for v) is about $4500.

Re_involt was working on Li replacement for Prius when they were bought out by Dorman. That was the end of that...I had thought I might do that.

 

I just diagnosed a bad dorman battery right out of the box. I repaired his old battery and sent the dorman battery back. XT1585 ? And lots of people (about $5500 customer pay in CT) pay that kind of money to keep their Prius going... I hate seeing people get screwed.

XT1585 ?

 

me too, but what is the alternative?

 

Yes they will die if you connect directly.

The company I work for makes the semiconductors used in the BMS systems of most EVs and we work closely with the auto manufacturers. We have done things nobody else has or thinks is possible yet. We know batteries and charging systems. You will get a boom if you hook up Toyota's NiMH system to any LiFePO4 battery pack with nothing inbetween.