# Calarin prototype buy list — 2026-04-12

## Buying philosophy
Do not let battery sourcing stall the whole prototype.

Order in two lanes:
- Lane A = real product direction
- Lane B = schedule hedge for bring-up

## Lane A — real product-direction battery
### Primary battery target: 302540 retail pack
Recommended retail-style options:

1. Ecocell 302540 LiPo 250mAh
- URL: https://ecocell.com.au/product/lipo-250-302540/
- Price signal: ~$6.95 inc GST
- Stock signal: 379 in stock
- Geometry: 40 × 25 × 3 mm
- Connector: JST-PH 2.0 preattached
- Protection: yes
- Notes:
  - easiest clean 302540 candidate found
  - low-drama buy for immediate testing

2. 99Tech 302540 LiPo 250mAh
- URL: https://99tech.com.au/product/lipo-250-302540/
- Price signal: ~$6.95
- Stock signal: 35 in stock
- Geometry: 40 × 25 × 3 mm
- Connector: JST-PH 2.0 preattached
- Protection: yes
- Notes:
  - same class, same basic proposition
  - good fallback if Ecocell stock moves

### Vendor/custom path: LP302540
- URL: https://www.lipobattery.us/lipo-battery-lp302540-3-7v-260mah/
- MOQ: 5 pcs
- Lead time signal: ~1 week if in stock
- Geometry: 3.0 × 25.0 × 40.0 mm
- Capacity: 260mAh
- Connector: none by default, 50mm wires only
- Protection: yes
- Notes:
  - use if we want custom connector / wire choice
  - slightly more friction, more flexible

## Lane B — bring-up hedge battery
### Fallback battery: 402030 retail pack
1. PMD Way 402030 LiPo 200mAh
- URL: https://pmdway.com/products/lithium-ion-polymer-battery-3-7v-200mah-402030
- Price signal: £15 single, cheaper in 5x / 10x packs
- Geometry: 40 × 20 × 3 mm listed on page
- Connector: JST-PH 2.0 preattached
- Protection: yes
- Notes:
  - easiest pure fallback option on the list
  - use only if 302540 sourcing delays battery-dependent bring-up

2. LiPol Battery LP402030
- URL: https://www.lipobattery.us/product/lp402030-3-7v-200mah-0-74wh/
- MOQ signal: 100 pcs on listing
- Geometry: 4.0 × 20 × 30 mm
- Connector: none by default, wires only
- Protection: yes
- Notes:
  - not ideal for prototype purchase unless we actually want a vendor run

## Core electronics to order now
### Must-buy prototype core
- ESP32-S3-WROOM-1 class module
- MSM261DGT003 microphone
- W25Q128JVSIQ flash
- IP5306-I2C power path parts
- ME6210A33M3G LDO
- USB-C connector in the chosen footprint family
- WS2812-class LED / chosen LED variant in schematic
- passives / switch / headers already represented in schematic

### Buying note
The battery choice should not hold the board-side parts hostage.
Order the core electrical set now.

## Recommended ordering move
If we want the cleanest next step, order:
- 2–4x Ecocell 302540
- 2–4x 99Tech 302540 only if we want a second retail source hedge
- 2–4x PMD Way 402030 as a bring-up hedge

That gives us:
- the right product-direction battery in hand
- a fallback if shipping or polarity weirdness bites us
- no excuse to keep debating batteries instead of prototyping

## My recommended exact move
Buy now:
1. Ecocell 302540 packs
2. PMD Way 402030 packs
3. core board parts

Only escalate to LP302540 vendor/custom ordering if:
- retail packs disappear
- we want connector changes
- we decide to optimize wire length / custom integration immediately

## Why this is the right order
- Ecocell 302540 = closest to the actual product vision
- PMD 402030 = schedule protection
- board parts = already de-risked by schematic/ERC closure