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@@ -14,7 +14,7 @@ Nighttime bicycle rides in the summer are ideal:
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- 🚘 little traffic
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- 🦝 nocturnal wildlife
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But it is not easy to see in the dark, so I bring a headlamp and okay, fine, this works. With my current head lamp I can see and be seen just fine. But there are some limitations. I see wonderfully directly ahead of me in the narrow cone of light provided, but at the edges of this light cone I see practically nothing at all, as though I am looking through a paper towel roll. The beam pattern is optimized for riding in a straight line, with little regard for what lies in the periphery. I would like a greater field of view, so I will need a lamp with a wide beam pattern.
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But it is not easy to see in the dark, so I bring a headlamp and okay, fine, this works. With my current head lamp I can see and be seen just fine. But there are some limitations. I see wonderfully directly ahead of me in the narrow cone of light provided, but at the edges of this light cone I see practically nothing at all, as though I am looking through a paper towel roll. The beam pattern is optimized for riding in a straight line, with little regard for what lies in the periphery. **I would like a greater field of view, so I will need a lamp with a wide beam pattern.**
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## 🔦 Headlamp
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I start by selecting the headlamp. This is the most important component, and everything will revolve around it. My selection criteria is simple. The light must have these features:
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@@ -41,19 +41,7 @@ I had to settle for the **OPL5 Motorcycle LED Headlamp**:
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{{< image src="images/opl5-motorcycle-led-headlamp.png" >}}
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## 🔋 Battery Sizing
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Since the headlamp consumes 48 W, I need a battery that can sustain this load for a couple of hours without totally draining the battery. I can see how long a given battery will endure.
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- $t$ = run time (hr)
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- $E_\text{battery}$ = battery energy (Wh)
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- $p_\text{load}$ = LED headlamp power (W)
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$$
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t = \frac{12.8 \text{ V} \cdot 16 \text{ Ah}}{48 \text{ W}} = 4.27 \text{ hr}
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$$
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✅ **This will work**. It is a comfortable, if not excessive, amount of energy for the headlamp.
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---
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## 🧰 Case
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I selected a cheap weatherproof case from *Harbor Freight Tools*. It will be large enough to accommodate many sizes of batteries, since battery packs of the nature I seek are almost always composed of a bunch of even smaller batteries, typically the 18650 type batteries. The dimensions of this battery type are also its namesake: **18 mm dia. × 65 mm l**.
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@@ -67,24 +55,40 @@ I mention all of this because the height dimension of the battery packs are almo
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{{< image src="images/apache-1800-case.png" >}}
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---
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## 🔋 Battery
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Since the headlamp consumes 48 W, I need a battery that can sustain this load for a couple of hours without totally draining the battery. I can see how long a given battery will endure.
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- $t$ = run time (hr)
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- $E_\text{battery}$ = battery energy (Wh)
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- $p_\text{load}$ = LED headlamp power (W)
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$$
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t = \frac{12.8 \text{ V} \cdot 16 \text{ Ah}}{48 \text{ W}} = 4.27 \text{ hr}
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$$
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I selected a cheap, unremarkable 12 V battery with a capacity of 16Ah.
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✅ This will be fine.
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{{< image src="images/nermak-12v-16Ah-LiFePO4.png" >}}
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✅ **This will work**. It is a comfortable, if not excessive, amount of energy for the headlamp.
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---
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## 🔌 Switches and Ports
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I splurged on a nice weatherproof SPST switch and mounting bracket.
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{{< image src="images/bss-contura-iii-spst.png" >}}
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{{< image src="images/bss-contura-iii-mounting-bracket.png" >}}
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The port that will feed power to the headlamp power is some kind of 'SAE' connector, which as far as I can tell do not actually comply with any official standard. They are used for a lot of things in weird cheap Chinese electronics, and I could have selected a better connector. I selected this mostly because it matches the connector on my battery charger and it is cheap and ubiquitous.
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The port that will feed power to the headlamp power is some kind of 'SAE' connector, which as far as I can tell do not actually comply with any official standard. They are used for a lot of things in weird cheap Chinese electronics, and I could have selected a better connector. I selected this mostly because it matches the connector on my battery charger and it is cheap and ubiquitous. It will be adequate.
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{{< image src="images/SAE-connector-socket.jpg" >}}
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---
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## 🔩 Parts List
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| Part |
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|-|
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@@ -94,9 +98,22 @@ The port that will feed power to the headlamp power is some kind of 'SAE' connec
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| SAE Power Socket Port |
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| Inline Blade Fuse Holder + 5 A Fuse |
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| Blue Sea Systems Contura III OFF-ON SPST Switch + Mounting Panel |
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| Double-sided adhesive tape |
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| Spade connectors |
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| Shrink tube |
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---
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## 🛠️ Assembly
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All that remains is to do final assembly. This is all very simple and I ran into no issues. Here is a **wiring diagram** of the circuit.
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Now for final assembly. This is all very simple and I ran into no issues.
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- Applied double-sided adhesive tape to fasten the battery enclosure to the box
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- Soldered on spade connectors to wires between switch and battery
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- Installed inline fuse
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- Sealed the power port and switch mounting holes with silicone
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- Removed the battery enclosure lid since the battery terminals were ≈ 1 mm proud of the battery box lid. The battery box would still close, but it was straining the plastic and the weather sealing would be compromised.
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Here is a **wiring diagram** of the circuit.
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{{< image src="images/bicycle-headlamp-wiring-diagram.svg" >}}
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@@ -107,17 +124,17 @@ All that remains is to do final assembly. This is all very simple and I ran into
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| SW1 | SPST Switch |
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| LED1 | 48 W |
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- Applied double-sided adhesive tape to fasten the battery enclosure to the box
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- Soldered on spade connectors to wires between switch and battery
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- Installed inline fuse
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- Sealed the power port and switch mounting holes with silicone
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- Removed the battery enclosure lid since the battery terminals were ≈ 1 mm proud of the battery box lid. The battery box would still close, but it was straining the plastic and the weather sealing would be compromised.
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I strap the battery box to the rear cargo rack with hook and loop straps.
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That is all.
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--
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## 🚴 Test Drive
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All that remains is the test drive.
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{{< image src="images/headlamp-night-test-drive.jpg" >}}
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🎉 **It works!**
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✅ Done.
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