The Sono Sion solar-supplemented electric car still hasn't started production, but on Thursday Sono Motors announced a larger battery pack for the vehicle, claiming longer range, more charging power, and a longer lifespan.

The new 54-kilowatt-hour lithium iron phosphate (LFP) pack replaces a 35-kilowatt-hour lithium-ion pack in the Sion. In a press release, Sono said it polled reservation holders (the company claims to have accepted more than 13,000 down payments so far), and over 90% voted for the more powerful battery.

Sono Sion LFP battery pack

Sono Sion LFP battery pack

Perhaps that's not surprising. With the new pack, Sono estimates 189 miles of range, up from about 160 miles before. Charging power has also been increased from 50 kilowatts to 75 kw, and the LFP pack has a longer lifespan of about 3,000 charging cycles, according to Sono.

The Sion is also covered with solar panels, which can provide up to 4,600 miles of driving range per year, Sono has claimed. That figure is unchanged by the new battery pack, according to the company.

Sono Sion solar assisted electric car

Sono Sion solar assisted electric car

Sono plans for production at the former Saab factory in Trollhättan, Sweden, under contract with National Electric Vehicle Sweden (NEVS), the entity that bought the factory and Saab's intellectual property after the automaker's 2011 bankruptcy. Sales will likely be limited to Europe. Sono has shown the Sion in the United States, but has no apparent plans to offer it here.

Both the Sion and the more upscale Lightyear One aim to virtually eliminate charging in vehicles that, at least somewhat, resemble normal cars. But solar-supplemented EVs face challenges, mostly stemming from the relative inefficiency of solar panels.