Over the past year I have been tossing around the idea of extending the electric range of my Cadillac ELR. I have wanted to build a large scale lithium battery system for some time and this seemed like a great way to learn about the technology.
I had originally started with the idea of charging the ELR hybrid pack while driving. The plan was to use a 48V to 390V (96S) lithium battery charger. Accessing the high voltage bus in the car proved to be challenging and made this approach too difficult for my taste. This made me decide build a portable L2 charger using a 240V inverter and an OpenEVSE instead.
Cadillac ELR Charging at Sierra Trail Head, No L2 Chargers for Miles
I used four battery modules from an old Enginer PHEV Conversion Kit, with a design capacity of more than 2kWh each. The total capacity is around 7kWh now as the cells are several years old and have seen some use. The results so far have been great with the system capable of charging the car to more than 60%.
In addition to being a great portable car charger, this has proven to serve well in powerwall applications. I am able to shift on-peak loads to off-peak, thus saving money and reducing reliance on dirty sources of power.
PortL2 Before Transferring to the Car
I used an Orion Jr. BMS to monitor the pack, perform cell balancing and monitor temperatures. The video above has a complete build log and you can find more details in the rest of this article.
