Electronics > Projects, Designs, and Technical Stuff

Electric car battery upgrade


I'm installing new batteries in my electric car, so I though I'd make some videos.

This is a converted Pontiac Firefly which I did about 5 years ago with a friend. It used to have 120V of 78Ah lead acid batteries. The old batteries were about 5 years old and in need of replacement, so I though I'd get some lithium ion batteries (144V 60Ah) instead of lead acid, to greatly increase the range and reduce the weight. The old batteries weighed 250kg, the new ones weigh 100kg and have about twice the energy storage.

Even though the Ah rating of the lead acid is higher than the lithium ion, the full capacity of lead is only achievable with lower discharge currents, the effective capacity goes way down with high discharge currents seen in an EV. Lithium keeps its capacity at much higher discharge currents. In this car, I was getting only about 30-35Ah real world out of the lead acid, while the lithium should maintain near its full 60Ah capacity.

I also had to modify the motor controller and DC-DC converter to work on the new 144V battery, they were 120V rated parts. Luckily there's enough margin in the design to handle the higher voltage.

Stay tuned, more videos are on the way too.

Controller/DC-DC Mods

Batteries and Busbars

Cell board installation/wiring



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