I have this same problem with my early '09 MacBook Pro 17" and new battery.
Although it ran on the AC adapter fine, my 2+ year old battery was not charging, and the magsafe charge indicator never showed amber before, during or after boot up. After replacing the battery the problem persisted, even after resetting SMC and PRAM multiple times. The new battery has gradually gone from showing 100% to 0% charge., and the macOS status shows "battery is not charging".
Do you thing the after market battery is the issue?
MacBookPro5,2 \ Mfg 2009-2-23 \ OSX El Capitan
Current Charge 46mAh
Full Chg Cap 16500 mAh \ bar meter shows 0.3%
Design Cap = 16000mAh \ bar meter shows 100%
mfg date 2018-12-23 \ cycle count 80
macOS Batt status Good \ Batt temp 21.1 C
Charging with 0 Watts \ Power Adapter Connected
MFG Simplo \ Age 61days \ Load cycles 80
macOS batt stat Good \ Batt temp 21.1C
Battery failure none \ Poweradapter 85Watts