I have (2) Inogen G5 batteries product numbers BA500, serial numbers 24401355 and 24402691....both were charged upon receipt as requested by Inogen"s packaged instructions.... Neither battery was ever used on the G5 portable oxygenator....I purchased these (2) batteries on 1/28/2025....the cost was $814.00 for both.... price is $500.00 for both. If interested, please advise.