ai:::ignore

title:::

set:::object_name jacket-design-v3

ai:::object get:::object_name

## AI convo

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Objective: To build a smart winter jacket with a lithium battery and 320 cm of heating wire.

ai:::completed watts Imagine an adult person who is wearing a normal jacket in a -10-celsius  winter. To make them feel warm, how many watts of energy should we add, so to speak, inside the jacket? This is the heat that is generated by this device.

ai:::ignore
- an adult at rest in extremely cold conditions (-10°C) loses about 100–150 watts of heat.
- 30 – 50% efficiency -> 200-350 watts
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ai:::completed current If we use a battery-capacity::: li-ion battery, connected in series, what is the nominal current that is drawn from the battery?

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- 5C x 5000 mAh -> each cell can supply 25 A
- 200 W == 18 A
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ai:::completed operation-time For how long can we keep this device on?

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- at 200 W: ~ 1 hour
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ai:::completed resistance What is the range of resistance per meter for heating wires?

common alloys:
- Nichrome: ~1.0 × 10⁻⁶ Ω·m
	- 5–10 Ω/m, for diameter=0.5 mm
- Kanthal: ~1.5 × 10⁻⁶ Ω·m.
	- ~6–12 Ω/m, for diameter=0.5 mm
- Carbon fiber: ~1.0 × 10⁻⁵ Ω·m

## summary

- n parallel heating wires, totaling $L$ meters -> each is $L/n$ long and with a resistance of $R$ = $L\rho/n$ (Ω).
- total power: P (w)

$$P=n\frac{v^2}{\frac{L\rho}{n}}=n^2\frac{v^2}{L\rho}$$

or,

$$\rho=\frac{n^2v^2}{LP}$$


at $P=100$ W, $L=3.2 m$, $v=3*3.7=11.1 V$, $n=4$ -> $\rho=6$ Ω/m ⭐️

## build

```bash
@sbc build_README \
	ai,root=shelter/jacket/design

@upload - get:::object_name
@upload public,zip get:::object_name
```

object:::get:::object_name

ai:::signature