So, we've made a lightweight 4 pound starter battery for gas cars. Took us several prototypes before we got to our final working configuration. Issues like power, charging, casing, configuration, balancing, hookup terminals, etc, had to be figured out. But in the end, it was worth it! We've saved almost 45 pounds from the BMW M3. Notice the lack of a spare tire in the M3, there's run-flat tires and an air compressor instead, to save weight. The stock 3 series has a spare.
This is the battery we are replacing! Notice how much smaller it's going to be.
A size comparison versus the stock M3 battery. The battery in front is from the Scion xA, and was hooked up so that we wouldn't lose our settings from the car.
Installed battery. We needed to use a one foot extension cable because the stock positive clamp on the M3 wasn't flexible enough to reach the positive terminal of the battery.
This is the battery we are replacing! Notice how much smaller it's going to be.
A size comparison versus the stock M3 battery. The battery in front is from the Scion xA, and was hooked up so that we wouldn't lose our settings from the car.
Installed battery. We needed to use a one foot extension cable because the stock positive clamp on the M3 wasn't flexible enough to reach the positive terminal of the battery.
