Yes, the "comercial" kit uses Li-Ion. The manufacturer claims 5yrs, and safe:

http://www.edrivesystems.com/faq.html

Of course, this FAQ comes from the manufacturer, so take it with a grain of salt. I have to search for others out there.

Hymotion warrants their battery for 2yrs now, but may extend that as more durability data comes in:

http://www.hymotion.com/faq.htm

calcars.org has lots of info, and links.

 

Here's another plug-in module manufaturer's faq:

http://www.hybrids-plus.com/ht/faq.html#toc43

Again, this is from a manufacturer, so I dont really know what's the real safety standard. I would suspect that Toyota is or have a solution. They are planning PHEV prius.

 

I love my Fords. Sice 1982 I have owned a 1982 Mercury Lynx Wagon, a 1989 Ford Taurus Wagon and a 1996 Ford Taurus Wagon. All have neared or exceeded 200,000 miles without major mechanical problems and have been maintained impecably.

My Mercury Mariner Hybrid is a technological breakthrough that offers higher mileage than my 1996 Taurus and all-wheel-drive. My average MPG is right around 37 with a daily commute of 94 miles roundtrip on I-15 (Ogden, Utah to Murray, Utah). That saves me about 5 gallons of fuel each week or 260 gallons a year.

It may never pay for irself, but it feels right having bought a vehicle that pollutes less, uses less foreign oil and was designed and built by Americans.

 

Still loving it! What a great car.