2002 Rav4EV Li conversion in 2017


Greetings all.

Many, many folks on this list have asked me for a “write up” of my LiPo conversion of my 2002 Rav4EV. I’ll take a first crack at it here, and I will attempt to be concise. Please understand that this was a years-long project that cannot be described in a few sentences.

The most common question - and the one I cannot and will not answer - is “how much does it cost?”  I don’t know the answer, so I cannot give you the answer. In big, round figures: It costs a lot. Certainly more than replacing the NiMH pack. And that’s because the Li batteries are expensive AND because of all the labor to put the square peg in the round holes, AND because an onboard charger needs to be added, as well as a BMS. And then all the work in having everything talk to everything else reasonably well. The car has to be fooled into thinking a few things to make it happy. Lots of cutting, gluing, wiring, fiddling.

When a conversion like this is done, there are many things that don’t work as they did before. The car becomes something that you can’t just operate with wild abandon. You don’t get to just hop in with the key, glance at the SOC meter and be on your way. You have to pay attention to when you can use the brakes normally (not above 80% SOC any longer!), and you don’t get to drive it down into the lower SOC just because you’re “in the green.” The dash gages are tricked into showing something that’s roughly accurate, and a new device is used to display the real data (via bluetooth). Without the new data display, you are driving blind, and destruction of the pack can come quickly and without warning. That’s a biggie: There is NO negative feedback when you do something wrong…. right up until you let the magic smoke out of the pack. If you slam on the brakes at 65 mph when the SOC is high, there will be no indication that you’re severely taxing the pack by trying to stuff 150 A into a bag that can old only one.

The great news is that the car is now noticeably lighter weight. I’m guessing about 450 pounds lighter. It sure stands higher on the springs. And when that lighter weight is coupled with higher Voltage (now 360V nominal) the acceleration is noticeably more snappy. Sadly - even though I have a bit more capacity in the pack, the range isn’t what it was with the NiMH pack. I have about 80 miles of range now. But at least those 80 miles are more fun!  

My car now sports a 5 kW elcon charger under the hood. I can charge from any J1772 EVSE - 110V-240V just by plugging in… like a new car! I can even simply charge directly from any electrical outlet of any flavor if I wish to bypass the J1772 for whatever reason. The Pilot signal and all that had to be added to the system to make it J1772 compatible. Natively, it just wants to be plugged into an outlet. Taking a portable charger (really, and EVSE, of course, as the charger is onboard)  along is now a dream! First, it will happily, automatically charge from 110, up to 240V without any modification. I can plug it into any outlet and get a charge. And it weighs maybe a couple of pounds. Yay! My car no longer has an SPI inlet, and my J1772 inlet is now where my SPI inlet used to be - behind the grille. To charge, the car must be in the “ready” mode. This is done automatically on my car when the J1772 connector is plugged in (through the use of relays to the ignition, so the key doesn’t need to be left in the car). The good news is that when charging, I can use ALL accessories if I wish. Heat, AC… anything. Because the car is truly ON. The bad news: the car is on and fully driveable when it is being charged. The overhead current consumption is about 0.7 A at idle, so that is subtracted from what the charger can supply to the battery pack. The car takes on charge at a nominal 13A, and in general charges more efficiently than it did on the SPI. The batteries take on charge more efficiently as well. So in the end, my 5 kW charger takes on about as much range per mile as the 6+ kW SPI charger offered.

I have 88 modules of Enerdel LiPo cells in series for 360V and 105 Ah. I have an Orion BMS in the battery tray. This means that my car has TWO BMS’s, and the Orion needs to always be booted first, or the OEM BMS will try to take control of batteries that no longer exist. This means that my Orion BMS is “always on” - so I leave a battery tender on my Aux battery 100% of the time now. The benefit is that the Orion is then allowed to always be balancing the pack - which it does amazingly efficiently.

My car still appears stock in almost all ways (though I removed the charge controller, because it is no longer relevant). It drives better than it ever has due to the lower weight and higher power. But much care needs to be taken in both charging and driving. One loose wire connection, in the hundreds of new connections that have now been made, can cause complete failure to charge or drive.

So… what else would you like to know? Do I recommend doing this? No. No, I don’t. I’m happy that I did it *now*, and I wouldn’t do it again. There are several shiny new EVs that I could have purchased for what this cost me - that would have had more power, more range, and turn-key simplicity, as well as modern safety equipment. But… like many of you… I really do love this car for many reasons. Sentimental value should not be dismissed - silly as that sounds. The EV1 meant a lot to me, and so does this car. The last EV we could purchase in that era. My car was abused each of the multple times it was transported, and that troubles me greatly. Before all this, my car was all but perfectly “straight.” I don’t think I’ll ever ship a car again if I can help it.

Nobody made money on this, and I was fortunately to have such expert help along the way. All told, this process took well over four years.

If you made it this far, and you want to see how good these car can still look - take a peek at photos that I took last week - after celebrating my car’s return with a multi-day detail session both inside and out. In these shots you’ll see the blue phone display that is my new BMS data. And of course you’ll see my dog. And a bunch of new LED exterior lighting.