This is a great question. Some companies do replace; no questions asked but some don't. I know Pedego considers depreciation on the battery even during the warranty period.
The warranty for replacement batteries will be based on the original battery purchase date, as identified on the original battery purchase sale receipt. Under no circumstance will a replacement battery have a warranty date different than the original battery purchase date. If a replacement is necessary due to a defect in materials and/or workmanship, then upon return to PEDEGO ELECTRIC BIKES: The battery will be replaced free of charge if it becomes defective during the first year. After that, a new battery replacement discount will be offered based upon the following formula:
Battery Replacement Price (New Battery Price at the Time of Return) divided by 1,905 (three years in days) times the number of days left on the three year warranty; For example: The battery was purchased new on Jan, 1, 2013 and a valide claim is made on December 31, 2015. The Battery Replacement Credit is $212 and is calculated as follows: $635 (List Battery Price for 2015) divided by 1,095 (3 years) = $0.5799 per day X 365 (365 = 1,905 – 730) where 730 is the number of days that the battery has been owned. In this case, a new battery can be purchased for $423 because the old battery had one year left on the pro-rata warranty.
Very interesting... Thanks for the the feedback and great attribution here Ravi. More and more ebike manufacturers are including water strips and other measuring devices inside their battery packs to determine who was at fault when a battery is returned. I think that's fair given some of the outrages returns these guys can get (it ends up costing all of us more money in the long run when they get away with a questionable return).
Visiting ProdecoTech once I was told about a bike that had been ridden through salt water in Florida and I've heard similar things when visiting Currie Technologies. BionX is working on a diagnostic network that will check the system over the internet (if you bring it into a shop and plug it in) and this allows them to diagnose issues and even de-activate the original pack if they determine it's unsafe or are sending a replacement. This is neat because it still allows them to replace the part but limits what might go wrong with the faulty pack. Neat stuff...