Some of you may remember that years ago I installed an Enginer (yes, that is actually spelled correctly)
PHEV kit in my 2004 Prius. This was actually a different Prius than I have now as the previous one was totaled by an inattentive driver that I t-boned. When I replaced the car, I never swapped the kit into the new Prius because it frankly never worked that great. I was still working bugs out, and didn't want to deal with it anymore. So, I sold it to another EcoModder.
However, I'm thinking I would like to give the PHEV Prius another try. With finding
Battery Hookup, lithium batteries are all too reasonably priced. If you wait for deal you can find cells for as low as $100/kWh! I think building a kit for around $1k could give some decent range, and I don't need a ton for my purposes.
This time I would not go for the Enginer type setup. It just didn't work well and I'm not willing to give it another go. However, there is a pretty snazzy device out there called the BMS plus 2. This BMS plus 2 is a computer that intercepts the CAN signals from the OE BMS ECU and alters them to suit our desires. This allows you to basically run a lithium pack in parallel with the OE nimh pack for additional capacity. It then tricks the SOC to use more assist than it normally would allowing some decent EV mode use, and also providing assist while in normal hybrid mode. I've still got a lot of reading to do on this thing, but thats the general idea in a couple sentences. It’s also basically what
Planetaire here on EcoModder uses in his PHEV Prius that is averaging some crazy mileage.
With the BMS plus 2 in place, all you really need to do is wire up a lithium pack in parallel with the OE pack and figure out a way to charge it. This parallel pack splits the current with the OE pack and should make life a lot easier for my OE pack.
The main issue I am having is that the BMS plus 2 is no longer in production. Thankfully, when the designer closed up shop he put out all the info you needed to make your own! So, I have been looking into this. There have been a few people that have made them since. I've been contacting them to see if they have a parts (it does require a custom circuit board) or are willing to make one. Right now I have a guy in Belgium who says he will make and test one for me, or just sell me parts.