Category: Electronics Workbench

Electrical & Electronic gadgets

Amber Side Marker Light Hackery

Start with the amber side marker light sporting a cataract and distorted beam:

Side Marker – beam test – E

Part off the lens:

Side Marker E – cutting case

The cut is just in front of the PCB and went slowly to avoid clobbering the SMD resistors very near the edge.

The cataract turned out to be crud adhered to the LED lens:

Side Marker E – LED cataract

Brutal surgery removed the LED and installed a replacement:

Side Marker E – replacement LED

The PCB had two 150 Ω SMD resistors for use with 12-ish V automotive batteries. While I had the hood up, I removed one and shorted across its pads to make the LED work with the 6 V switched headlight supply from the Bafang motor.

In round numbers, 6 V minus 2.2 V forward drop divided by 150 Ω is about 25 mA. The original LED ran at 35-ish mA, but it’s close enough.

Glue the lens back in place:

Side Marker E – clamping case

The bubbly stuff is solid epoxy from the original assembly, which is why removing the PCB is not an option.

The new LED is no more off-center than any of the others:

Side Marker E – new LED – front

It does, however, sit much closer to the lens, due to the ring of plastic I cut away to get inside. As a result, the beam is mostly a single centered lobe with only hints of the five side lobes; there isn’t much waste light from the side of the LED into those facets.

Replace the one I originally put in the new fairing mount:

Side Marker E rebuilt – installed

However, it’s still not much more than a glowworm in the daytime, so we need more firepower …

2021-07-22
Bafang Charger Cord Anchor

The Bafang battery charger uses an AC line cord “binocular” connector with what must be the weakest spring contacts ever made, which finally annoyed me enough to fix:

Bafang charger – AC line cord anchor

Also, the case now sports four thick fuzzy felt feet to keep it from sliding around quite so easily.

Another customer-does-the-last-ten-percent product …

2021-07-20
Power Outage

A gusty thunderstorm knocked out power across Dutchess County, including half the service to our house. Being glad the refrigerator and freezer were on the live phase, I shut off the affected breakers on the dead phase, as well as all the 240 V breakers, and, with the living room darkened, we skipped our evening storytime.

By the next morning, a quick lamp test showed the recloser out on the pole had worked its magic, so I flipped all the breakers back on. The living room remained dark, prompting an investigation of the fuse box feeding the original house wiring:

Blown 20 A glass fuse

Yup, another blown fuse.

Given what happens while wind and falling branches knock power lines askew, anything is possible. I have no idea where the fault current went, but replacing the fuse brought the living room back to normal.

None of the various UPS / lamps / phones seem damaged; I admit not peering inside the outlets to check for arc damage.

2021-07-10
Side Marker Beam Patterns: FAIL
The truck side marker lights I’m thinking of using as daytime running lights have a pentagonal lens, so they should have a pattern with a bright central beam surrounded by five lobes. The one on Mary’s Tour Easy produced an oddly shaped blotch on the garage wall, so I ran the others though a simple test setup:

Side Marker – beam test setup

The lights sit horizontally in a small vise to keep them level and in the same position, although in no particular rotational orientation, and 100 mm from the graph paper. It’s running at 6 v to keep the brightness down enough to avoid blowing out the image. All of the images were exposed based on the central spot, so the surrounding paper gives some idea of the relative brightness: darker paper = brighter LED spot.

The front view of the lights comes from the stereo zoom microscope, with the wires gripped in a Third Hand and rotated to put the (inverted) TOP label where you’d expect it. They’re all roughly at the same position and pretty nearly lined up with the lens axis. The bubble-looking thing behind the central pentagon is the lens on the Piranha LED package, which should be centered but rarely is. You can see the dark orange square of the amber LED chip in some of the pictures.

Without further ado, the nine truck side marker lights that aren’t on her bike:
- Side Marker – beam test – A
- Side Marker – beam test – B
- Side Marker – beam test – C
- Side Marker – beam test – D
- Side Marker – beam test – E
- Side Marker – beam test – F
- Side Marker – beam test – G
- Side Marker – beam test – H
- Side Marker – beam test – I
Side Marker Light – Beam tests
Side Marker E has a blob that looks like a cataract atop the LED lens, but it might be a mold imperfection.

Obviously, paying a buck a light doesn’t get you much in the way of build quality these days.
2021-07-08
Tour Easy: Amber DRL Internal Resistor

Plotting current against voltage for the amber truck side marker lights produces the expected straight-ish line:

Side Marker I vs V plot – with fuse

The slope suggests a 330 Ω resistor, but the internal PCB sports a pair of 150 Ω SMD resistors.

I don’t believe the X-axis intercept for a moment, but 1.5 V seems about right for an amber LED.

Oh, and the DMM fuse doesn’t have a ceramic body. You’re seeing the vaporized remains of a 315 mA fuse neatly deposited over the inside of the glass tube after being shorted across a 3 A bench supply.

I hate it when that happens. Replacing it emptied the little bag of those meter fuses; next time it’ll get a half amp fuse.

2021-07-07
Tour Easy: Amber Running Light
Having seen a few bikes with amber “headlights” and being desirous of reducing the number of batteries on Mary’s bike, this seems like an obvious first step:

Fairing Mounted Side Marker – First Light

It descends from the fairing flashlight mount with an entry to suit a 15 mm truck side marker body:
```
LightBodies = [
  ["AnkerLC90",26.6,48.0],
  ["AnkerLC40",26.6,55.0],
  ["J5TactV2",25.0,30.0],
  ["InnovaX5",22.0,55.0],
  ["Sidemarker",15.0,20.0],
  ["Laser",10.0,30.0],
];
```
The rest of the code gets a few cleanups you’d expect when you compile code untouched for a few years using the latest OpenSCAD.

The markers are allegedly DOT rated, which matters not for my use case: SAEP2PCDOT.

The mount is grossly overqualified for a wide-beam light with little need for aiming:

Fairing Mounted Side Marker – test light

Eventually, the marker should slip into a prealigned cylindrical holder, with a dab of epoxy to keep it there.

The lights are a buck apiece, so there’s no reason to form a deep emotional attachment. They are the usual poorly molded and badly assembled crap, although the next step up from a nominally reputable supplier is a factor of five more expensive.

It’s generated for the left side of the fairing, although I think having a pair of them would improve conspicuity:

Fairing Mounted Side Marker – installed

Being automotive, it runs from a 12 V supply, which comes from a boost converter driven by the Bafang 6 V headlight output. The absurdity of bucking a 48 V lithium battery to a 6V switched headlight output, then boosting it to 12 V to drive a single amber LED with a 1.5 V forward drop does not escape me.

It’s possible to slice the lens off (using a lathe), remove / replace the resistor, then glue it back together, which would be worthwhile if you were intending to drive it from, say, an Arduino-ish microcontroller to get a unique blink pattern.

Given the overall lack of build quality, it might make more sense to slap a condenser lens in front of a Piranha LED.

Bonus: contrary to what you (well, I) might expect, the black lead is positive and the white lead is negative.
2021-07-06

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%

Bafang BBS02 on Terry Symmetry – actual voltage

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%

Bafang BBS02 on Terry Symmetry – nominal voltage

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.

Terry Symmetry - Tour Easy — Terry Symmetry – Tour Easy

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

2021-07-01

Category: Electronics Workbench

Amber Side Marker Light Hackery

Bafang Charger Cord Anchor

Power Outage

Side Marker Beam Patterns: FAIL

Tour Easy: Amber DRL Internal Resistor

Tour Easy: Amber Running Light

Bafang BBS02: Assist Power Levels