ทำไมต้องจำนวนแบตฯเลขคี่

#1 · February 4, 2026, 09:09

Quote from nongferndaddy on February 4, 2026, 09:09
ผมน่ะขี้รำคาญมากๆ เวลาซื้ออุปกรณ์อิเลคฯจีน มันชอบออกแบบมาให้ใช้แบตฯเป็นจำนวนคี่ โดยเฉพาะ 3 กับ 5 ก้อน แต่เวลาร้านบ้านเราขาย ดันขายแพ็คเป็นจำนวนคู่ เช่น 2 4 6 ก้อน ซื้อมาแล้วก็เหลือเศษ ไม่รู้จะเอาไปยัดใส่อะไร

ผมก็ไม่รู้ว่าผมคิดเองเออเองหรือเปล่า วันนี้ว่างๆเลยถามเอไอสัญชาติจีน

ได้คำตอบมาประมาณนี้

------------------
หนังสือ ครอบครัวตึ๋งหนืด ฉบับ ซุปเปอร์ตืด รวมตอนเด็ด 14-15 มือสอง สภาพ 90%

https://raka.is/r/ArrrW
------------------

That's a very insightful observation! The use of 3 or 5 batteries in many Chinese-made (and indeed, most) consumer electronics is not arbitrary, but a direct result of the fundamental electrical design requirements. The reason boils down to one key concept: Voltage.

Here’s a breakdown of why odd numbers are so common:

1. The Core Reason: Standard Battery Voltage

· A standard AA, AAA, C, or D battery has a nominal voltage of 1.5V when it's a common alkaline or carbon-zinc type.

· If you connect batteries in series (end-to-end, the most common configuration in a simple battery holder), their voltages add up.

· Therefore:

· 3 batteries in series provide 4.5V (3 × 1.5V).
· 5 batteries in series provide 7.5V (5 × 1.5V).

2. Why These Voltages? The Role of the Voltage Regulator

Most modern electronic devices (LED lights, toys, radios, etc.) don't run directly on 4.5V or 7.5V. Their internal chips and components (like microcontrollers, amplifiers, and LEDs) typically require a stable 3.3V or 5V.

This is where a crucial component called a voltage regulator comes in. Its job is to take the higher, fluctuating voltage from the batteries and convert it down to a clean, stable voltage the circuit needs.

· A 3-battery pack (4.5V) is an excellent, efficient source for a 5V regulator or a 3.3V regulator. The regulator has just enough "headroom" (difference between input and output) to work efficiently without wasting too much power as heat.

· A 5-battery pack (7.5V) is often used for devices that need a bit more power (like some motorized toys or brighter lights) but still regulate down to 3.3V or 5V internally. It can also be a design choice to ensure the device works well even as the batteries drop to around 1.2V each (a common end-of-life voltage for rechargeables), giving ~6V, which is still enough for the regulator.

3. Why NOT Even Numbers?

Using an even number of 1.5V batteries creates voltages that are less optimal for the standard 3.3V/5V electronics world:

· 2 batteries = 3.0V: This is too low to reliably feed a 3.3V regulator (it needs input higher than 3.3V). It might only be used in very simple devices (like some LED flashlights) that run directly off the battery voltage without complex electronics.

· 4 batteries = 6.0V: This is a somewhat awkward voltage. It's too high for a simple 3.3V circuit (wasting more energy as heat in the regulator) and not meaningfully better than 4.5V for a 5V circuit. It's less efficient and offers little advantage over the 3-battery design.

· 6 batteries = 9.0V: This is common in a different form factor—the 9V battery itself (which is internally made of six AAAA cells). It's used in devices like smoke detectors, older guitar pedals, or higher-voltage applications. For standard 5V electronics, 9V is quite high, leading to significant energy loss and heat in the regulator unless specifically needed.

Important Nuances:

· Rechargeable Batteries: NiMH or NiCd rechargeable batteries have a nominal voltage of 1.2V each. So, a 3-pack of rechargeables provides 3.6V, and a 5-pack provides 6.0V. Device designers often account for this, ensuring their voltage regulators can handle the range from fresh alkalines (~1.6V each) to depleted rechargeables (~1.0V each).

· Lithium Batteries: This logic changes with Lithium-based batteries (like 18650 cells or Li-Po packs), which have a nominal voltage of 3.7V. Here, you'll see even numbers (e.g., 2 in series for 7.4V, 3 for 11.1V) to match the needs of higher-voltage devices like laptops, power tools, and electric vehicles.

· Form Factor & Cost: Using 3 or 5 standard cells often creates a convenient, ergonomic shape for handheld devices (like a long, thin flashlight or grip) and is the most cost-effective way to reach the required input voltage for the regulator.

In summary: The prevalence of 3 or 5 battery slots in Chinese-made electronics is a global design standard driven by the need to efficiently generate a voltage (4.5V or 7.5V) that is optimally suited to be regulated down to the 3.3V or 5V required by modern electronic components, while also accommodating the characteristics of both alkaline and rechargeable batteries.

ผมเช็คกับเพื่อนที่เป็นเซียนเรื่องนี้ มันก็บอกว่า จริงนะ โดยแถมให้ว่า จีนรู้ว่าเดี๋ยวนี้คนไม่ใช้แบตฯก้อนที่ชาร์จกันแล้ว เฮียเลยออกแบบมาให้ใช้กับแบตฯปกติ (1.5 V) อย่างเดียว แต่ถ้าจะออกแบบให้ชาร์จได้ เฮียจะทำแบบ build in ลิเทียมไอออน เลย

พ่อน้องเฟิร์นและน้องภัทร
.
ถ้าจะซื้อของใน shopee หรือ lazada อยู่แล้ว เข้าทางนี้ (gate way) เลยครับ ผมจะได้ค่าคอมฯ ถือว่าช่วยผมจ่ายค่าเช่า host server ไม่ใช่คลิ๊กดูดเงินแน่นอนครับ ไม่ต้องกังวล …. ขอบคุณครับ
.
Shopee
https://raka.is/r/gP7GV
Lazada
https://raka.is/r/qlzXR

ผมน่ะขี้รำคาญมากๆ เวลาซื้ออุปกรณ์อิเลคฯจีน มันชอบออกแบบมาให้ใช้แบตฯเป็นจำนวนคี่ โดยเฉพาะ 3 กับ 5 ก้อน แต่เวลาร้านบ้านเราขาย ดันขายแพ็คเป็นจำนวนคู่ เช่น 2 4 6 ก้อน ซื้อมาแล้วก็เหลือเศษ ไม่รู้จะเอาไปยัดใส่อะไร

ผมก็ไม่รู้ว่าผมคิดเองเออเองหรือเปล่า วันนี้ว่างๆเลยถามเอไอสัญชาติจีน

ได้คำตอบมาประมาณนี้

------------------
หนังสือ ครอบครัวตึ๋งหนืด ฉบับ ซุปเปอร์ตืด รวมตอนเด็ด 14-15 มือสอง สภาพ 90%

https://raka.is/r/ArrrW
------------------

That's a very insightful observation! The use of 3 or 5 batteries in many Chinese-made (and indeed, most) consumer electronics is not arbitrary, but a direct result of the fundamental electrical design requirements. The reason boils down to one key concept: Voltage.

Here’s a breakdown of why odd numbers are so common:

1. The Core Reason: Standard Battery Voltage

· A standard AA, AAA, C, or D battery has a nominal voltage of 1.5V when it's a common alkaline or carbon-zinc type.

· If you connect batteries in series (end-to-end, the most common configuration in a simple battery holder), their voltages add up.

· Therefore:

· 3 batteries in series provide 4.5V (3 × 1.5V).
· 5 batteries in series provide 7.5V (5 × 1.5V).

2. Why These Voltages? The Role of the Voltage Regulator

Most modern electronic devices (LED lights, toys, radios, etc.) don't run directly on 4.5V or 7.5V. Their internal chips and components (like microcontrollers, amplifiers, and LEDs) typically require a stable 3.3V or 5V.

This is where a crucial component called a voltage regulator comes in. Its job is to take the higher, fluctuating voltage from the batteries and convert it down to a clean, stable voltage the circuit needs.

· A 3-battery pack (4.5V) is an excellent, efficient source for a 5V regulator or a 3.3V regulator. The regulator has just enough "headroom" (difference between input and output) to work efficiently without wasting too much power as heat.

· A 5-battery pack (7.5V) is often used for devices that need a bit more power (like some motorized toys or brighter lights) but still regulate down to 3.3V or 5V internally. It can also be a design choice to ensure the device works well even as the batteries drop to around 1.2V each (a common end-of-life voltage for rechargeables), giving ~6V, which is still enough for the regulator.

3. Why NOT Even Numbers?

Using an even number of 1.5V batteries creates voltages that are less optimal for the standard 3.3V/5V electronics world:

· 2 batteries = 3.0V: This is too low to reliably feed a 3.3V regulator (it needs input higher than 3.3V). It might only be used in very simple devices (like some LED flashlights) that run directly off the battery voltage without complex electronics.

· 4 batteries = 6.0V: This is a somewhat awkward voltage. It's too high for a simple 3.3V circuit (wasting more energy as heat in the regulator) and not meaningfully better than 4.5V for a 5V circuit. It's less efficient and offers little advantage over the 3-battery design.

· 6 batteries = 9.0V: This is common in a different form factor—the 9V battery itself (which is internally made of six AAAA cells). It's used in devices like smoke detectors, older guitar pedals, or higher-voltage applications. For standard 5V electronics, 9V is quite high, leading to significant energy loss and heat in the regulator unless specifically needed.

Important Nuances:

· Rechargeable Batteries: NiMH or NiCd rechargeable batteries have a nominal voltage of 1.2V each. So, a 3-pack of rechargeables provides 3.6V, and a 5-pack provides 6.0V. Device designers often account for this, ensuring their voltage regulators can handle the range from fresh alkalines (~1.6V each) to depleted rechargeables (~1.0V each).

· Lithium Batteries: This logic changes with Lithium-based batteries (like 18650 cells or Li-Po packs), which have a nominal voltage of 3.7V. Here, you'll see even numbers (e.g., 2 in series for 7.4V, 3 for 11.1V) to match the needs of higher-voltage devices like laptops, power tools, and electric vehicles.

· Form Factor & Cost: Using 3 or 5 standard cells often creates a convenient, ergonomic shape for handheld devices (like a long, thin flashlight or grip) and is the most cost-effective way to reach the required input voltage for the regulator.

In summary: The prevalence of 3 or 5 battery slots in Chinese-made electronics is a global design standard driven by the need to efficiently generate a voltage (4.5V or 7.5V) that is optimally suited to be regulated down to the 3.3V or 5V required by modern electronic components, while also accommodating the characteristics of both alkaline and rechargeable batteries.

ผมเช็คกับเพื่อนที่เป็นเซียนเรื่องนี้ มันก็บอกว่า จริงนะ โดยแถมให้ว่า จีนรู้ว่าเดี๋ยวนี้คนไม่ใช้แบตฯก้อนที่ชาร์จกันแล้ว เฮียเลยออกแบบมาให้ใช้กับแบตฯปกติ (1.5 V) อย่างเดียว แต่ถ้าจะออกแบบให้ชาร์จได้ เฮียจะทำแบบ build in ลิเทียมไอออน เลย

พ่อน้องเฟิร์นและน้องภัทร
.
ถ้าจะซื้อของใน shopee หรือ lazada อยู่แล้ว เข้าทางนี้ (gate way) เลยครับ ผมจะได้ค่าคอมฯ ถือว่าช่วยผมจ่ายค่าเช่า host server ไม่ใช่คลิ๊กดูดเงินแน่นอนครับ ไม่ต้องกังวล …. ขอบคุณครับ
.
Shopee
https://raka.is/r/gP7GV
Lazada
https://raka.is/r/qlzXR