Fortress Power

Well, I found the Fortress battery warranty policy buried on their webpages, under the warranty claim page ... 10 year warranty in both USA/Canada.  Only 5 years for marine installations or installations outside of USA/Canada. They indeed do not specify any user meaningful performance metric.   It's a pro-rated warranty.  Note that they don't state how it's prorated years or cycles - based on whatever is more favourable to them in each case?

The Fortress Power Lithium Ferrite Phosphate Batteries LFP-5/10, eFlex, and eVault (“Product(s)”) as supplied and distributed by Fortress Power, LLC, (“Fortress Power”) a Pennsylvania corporation, are warranted (the “Limited Warranty”) by Fortress Power, LLC against manufacturing defects in materials and workmanship. Within the United States and Canada coverage is on a prorated basis for a period of ten (10) years (“10 Year Limited Warranty Period”); or for 6,000 cycles, 80% DOD; or for 2000 cycles, 100% DOD; whichever comes first. Outside the United States and Canada coverage is for a period of (5) years (“5 Year Limited Warranty Period”); or 3,000 cycles, 80% DOD: or for 1000 cycles, 100% DOD; whichever comes first. All installations of Fortress Products worldwide on marine vessels or mobile vehicle applications are covered by the 5 Year Limited Warranty Period. To be eligible, all Fortress Products must be installed by a licensed professional using the Fortress Power Installation Manual and the Fortress Power Integration Guide (both available at www.fortresspower.com/resources) 

This warranty policy is open to mis-interpretation or dispute as they guarantee lifetime energy throughput at various cycle drawdowns (Depth of discharge DOD) levels of 80%, 90% and 100% - with dramatic drop in capacity at 100%DOD).  But they don't state how the cycle history is determined or how these projected capacities are related to the warranty. 

So if you draw the battery down once to DOD of 100% (i.e. in a capacity test) you automatically only get the lower level of guaranteed lifetime energy throughput??   Also, they don't specify how the warranty claim is evaluated - by internal logging?  There is no mention of guaranteed cycle capacity through the warranty period, only number of cycles vs DOD.   Also, must be installed by "licensed" professional, whatever that means (guy with a driver's license?).