Bafang BBS02: Assist Power Levels

Although Gee’s Terry Symmetry is sized for female bodies, I managed to ride it up and down the driveway while watching the power display:

Voltage		52.5
Rated Current		24
Max current		18
			Power	Power
PAS	Assist	Amp	Calc	Observed	Ratio
0	0%	0.0	0	0	~
1	4%	0.7	38	26	69%
2	6%	1.1	57	52	92%
3	9%	1.6	85	78	92%
4	13%	2.3	123	104	85%
5	20%	3.6	189	182	96%
6	30%	5.4	284	258	91%
7	50%	9.0	473	453	96%
8	85%	15.3	803	675	84%
9	100%	18.0	945	900	95%

The variations in the last column suggest my data-taking is … wobbly, at best.

I think the displayed power does not come from actual current and voltage measurements, because recalculating the power using the nominal 48 V battery value produces an unnatural agreement:

Voltage		48
Rated Current		24
Max current		18
			Power	Power
PAS	Assist	Amp	Calc	Observed	Ratio
0	0%	0.0	0	0	~
1	4%	0.7	35	26	75%
2	6%	1.1	52	52	100%
3	9%	1.6	78	78	100%
4	13%	2.3	112	104	93%
5	20%	3.6	173	182	105%
6	30%	5.4	259	258	100%
7	50%	9.0	432	453	105%
8	85%	15.3	734	675	92%
9	100%	18.0	864	900	104%

The motor controller may measure the actual winding currents while generating the BLDC waveforms, but the values may not be available to the display at the end of the cable. If Bafang documented the commands & responses, we’d know for sure, but they don’t.

Those assist values come from Mary’s Tour Easy, a much heavier bike than the Symmetry, but the first few levels work well in my limited tests. The highest levels may be too peppy for Gee’s normal routes, but having some serious boost in reserve can defang (hah) the worst hills.

IMO, the bike would burn rubber at the motor’s full 24 A current …