Battery Monitor,Discovery Buzzer,Signal Loss Alarm – 3 in1

Out of production and stock since May.2018, There are many fakes in market.


More Info


It is a 3in1 gadget with LiPo Battery monitor, Discovery buzzer & Signal loss alarm functions. Buildin ultrahigh brightness LED & twin loud buzzers


  • Working voltage: 5.2~26V DC, 2~6Cells LiPo
  • Standby current less than 10mA
  • Working current, Max 120mA (blinking & beeping)
  • Voltage threshold setting: 3.4~3.7V/cell (Red LED)
  • Twin loud buzzers, 85db each
  • Ultrahigh Brightness LED, 20lm, 0.2w, Blue
  • Size: 20x30x6mm,
  • Weight: 7g

【How to use】

1. Battery monitor function (F1)

  • It can monitor 2~6S LiPo voltage status & notify you once the cells reach the defined voltage.
  • The voltage threshold of alarm & flash can be customized between 3.4V~3.7V/Cell.

1.1 If the LiPo voltage is in the range of following, The BM3in1 will detect the cell numbers automatically when the LiPo is connected.

  • 7.4~8.6V: 2cells LiPo
  • 11.1~12.9V: 3cells LiPo
  • 14.8~17.2V: 4cells LiPo
  • 18.5~21.5V: 5cells LiPo
  • 22.2~25.8V: 6cells LiPo

The BM3in1 will alarm “Be” & the voltage threshold red LED will be shown.

  • Hold the button 3 seconds to enter the setting of the voltage threshold.
  • Press button to set the alarm threshold between 3.4~3.7V/Cell(red LED) .
  • The value will be saved & exit if no action within 10 seconds.

During the using of LiPo, BM3in1 will detect the voltage always.
If the total voltage is below “threshold * cells”, the alarm & blink will be triggered with “Be..Be..Be……”
If the total voltage rise again, the alarm & blink will be suspended.

1.2 If the LiPo voltage is out of the aforesaid range. The BM3in1 will alarm “Be..Be..Be” & 4 red LEDs light. Pls check if the battery total voltage is below 3.7V*cells

2. Discovery buzzer function (F2)

It is easy to use the function, Just plug it in one Aux channel(e.g. Gear).
Move the toggle switch to one side or another side, the BM3in1 will alarm “BeBeBeBeBe” & blue LED blink.

3. Signal loss alarm function (F3)

It can warn you if you turn off the transmitter first by mistake, if you have trouble finding a model in the long grass…

Turn on the transmitter first. Hook BM3in1 to the receiver THRO channel, then plug battery into model. It will detect the loss of TX signal, and emit a loud alarm “BeBe…BeBe…BeBe…” & the blue LED blink.

RX power on, the alarm & blink will be triggered as following

  • Turn off the transmitter first. and keep one minute.
  • The radio power on, but no action of stick or no signal change within one minute.



  • 工作电压范围:5.2~26V DC, 2~6Cells LiPo
  • 静态功耗:10mA
  • 最大工作电流:120mA (LED闪烁并蜂鸣时)
  • 输入电压截止设定:3.4~3.7V/cell (红色LED指示)
  • 双蜂鸣器,85db+85db
  • 超亮蓝色5050 LED, 20流明,0.2w
  • 尺寸和重量:20x30x6mm,7g


1. 电显功能 (F1)
可以监控 2~6S LiPo 使用中的实时总电压,一旦电压降到所设定的截止值, 即触发报警提示。电压截止值可设定范围:3.4V~3.7V/Cell

1.1 当接入LiPo电池时,如果电池组的总电压在下列范围, 三合一会自动判断电池组单元数。

  • 7.4~8.6V: 2cells LiPo
  • 11.1~12.9V: 3cells LiPo
  • 14.8~17.2V: 4cells LiPo
  • 18.5~21.5V: 5cells LiPo
  • 22.2~25.8V: 6cells LiPo

三合一会发出一声 “Be” ,并且红色LED会点亮,指示之前保存的截止电压值。

  • 长按按键3秒可进入截止电压值设定
  • 短按按键可在3.4~3.7V内选择合适的截止电压值(红色LED指示)
  • 10秒内无按键动作,自动保存当前值并退出


  • 如果总电压低于“截止值×单元数”,将触发报警,蓝色LED闪烁,蜂鸣器持续 “Be..Be..Be..Be….”
  • 如果总电压回升到“截止值×单元数”之上,报警暂停。

1.2 当接入LiPo电池时,如果电池组的电压不在上述范围. 三合一会提示 “Be..Be..Be” 并且4个红色LED全亮,请检查此电池组电压是否过低不适合继续使用。

2. 追踪器功能 (F2)

不管向任何方向拨动通道开关,蜂鸣器会叫五声 “BeBeBeBeBe”,并伴随蓝色LED闪烁。

  • 此功能必须要求接收机有信号,人为主动触发报警提示。

3. 失控报警功能 (F3)



  • 先关了发射机,一分钟内没有打开,接收机没有收到信号,会触发报警。
  • 发射机打开时,一分钟内没有检测到摇杆动作,或者没有信号变化,会触发报警。

报警提示为持续的 “BeBe…BeBe…BeBe…” 并伴随蓝色LED闪烁。

  • 报警触发后,如接收机收到号变动,会自动解除。


  • We foung some fake BM3in1 in the market from Sept.2015.
  • The fake 3in1 copied our packing, including logo, manual & Head card. and they also copied our pictures.
  • Pls pay attention to the font difference.



BM3in1 introduction video / 使用介绍视频

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