Reasoning
Cross-source evidence shows 450 mAh as the common, corroborated value: OscarLiang lists 450 mAh with high confidence, and Betafpv.com includes 450 mAh at high confidence alongside 550 mAh. Since the manufacturer-domain data appears alongside a trusted review, and 550 is not consistently supported across sources, 450 mAh is the most credible single value.