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.
Source:
https://www.pedegoelectricbikes.com