Converted 1993 Stumpjumper to have Bafang BBS02  750 W with Hailong 48 V battery

Symptoms:

Mostly: surging/deceleration at level 2 (or any other level). Charge level drops, increases without heavy loading – even at coasting.

Occasionally: powers off when coming to a stop.

Noted: powering up: display sometimes takes long time (10+ secs) to indicate full charge.

Actions taken:

Tested Battery: full voltage

Cleaned: Connectors with topical fluid cleaner

Mounted on bike stand for testing after cleaning connectors: power up normal, stepping for 0-5 ok.

After bike stand test, road test. Fails with surging/deceleration, and charge level drops, increases without heavy loading.

Suggestions????

Additional questions: is there an inexpensive controller tester that can test Bafang’s controller such as

Amazon.com: ZHANGLI E-Bike Tester 24V/36V/48V/60V/72V Brushless MotorTester with Indicator, Portable Riding Quick Battery Powered Spared Device Tester Controller : Sports & Outdoors