Well designed. The alarm is quite loud. It beeps twice when you plug in your battery. I hold my meaty finger over the buzzer to muffle it so I don't startle everybody around me. You can adjust the voltage at which the alarm goes off, which is just fantastic. Instructions for making the adjustment are printed in tiny tiny lettering on the back. The display is very bright, easily visible from short distance depending on your eye sight. The display cycles between showing the total voltage of your battery pack, then each individual cell. The display changes too quickly for my liking. It measures 39 x 25 x 11 mm, and weights 9.6, lets say 10 grams, which should be no problem for an under-powered 4-channel 400 size helicopter and probably still manageable for a 200. If they used smaller 7-segment LEDs, a single buzzer, and it only had the ability to read 1S to 4S packs, it could be a third of the weight. There is very little to complain about.I bought 3 of them - should have bought 12!

Well designed. The alarm is quite loud. It beeps twice when you plug in your battery. I hold my meaty finger over the buzzer to muffle it so I don't startle everybody around me. You can adjust the voltage at which the alarm goes off, which is just fantastic. Instructions for making the adjustment are printed in tiny tiny lettering on the back. The display is very bright, easily visible from short distance depending on your eye sight. The display cycles between showing the total voltage of your battery pack, then each individual cell. The display changes too quickly for my liking. It measures 39 x 25 x 11 mm, and weights 9.6, lets say 10 grams, which should be no problem for an under-powered 4-channel 400 size helicopter and probably still manageable for a 200. If they used smaller 7-segment LEDs, a single buzzer, and it only had the ability to read 1S to 4S packs, it could be a third of the weight. There is very little to complain about.I bought 3 of them - should have bought 12!

Well designed. The alarm is quite loud. It beeps twice when you plug in your battery. I hold my meaty finger over the buzzer to muffle it so I don't startle everybody around me. You can adjust the voltage at which the alarm goes off, which is just fantastic. Instructions for making the adjustment are printed in tiny tiny lettering on the back. The display is very bright, easily visible from short distance depending on your eye sight. The display cycles between showing the total voltage of your battery pack, then each individual cell. The display changes too quickly for my liking. It measures 39 x 25 x 11 mm, and weights 9.6, lets say 10 grams, which should be no problem for an under-powered 4-channel 400 size helicopter and probably still manageable for a 200. If they used smaller 7-segment LEDs, a single buzzer, and it only had the ability to read 1S to 4S packs, it could be a third of the weight. There is very little to complain about.I bought 3 of them - should have bought 12!

This li-po battery voltage checker is a very valuable tool for your rc helicopter. It can test the voltage of any battery anywhere. I checked it's accuracy against my VOM and it is right on. But the real value is when you use it as a low voltage warning system to protect your li-po's. You can set the voltage limit with the button on top of the unit. Then with a small velcro dot you can mount it, and plug it into the balance plug on your heli. When the set voltage is reached, the alarm will sound and you can land. You can hear the alarm across a large field. It will keep you from running your li-po voltage too low thereby extending the battery life. This is a very useful tool and very accurate. A great buy.

This li-po battery voltage checker is a very valuable tool for your rc helicopter. It can test the voltage of any battery anywhere. I checked it's accuracy against my VOM and it is right on. But the real value is when you use it as a low voltage warning system to protect your li-po's. You can set the voltage limit with the button on top of the unit. Then with a small velcro dot you can mount it, and plug it into the balance plug on your heli. When the set voltage is reached, the alarm will sound and you can land. You can hear the alarm across a large field. It will keep you from running your li-po voltage too low thereby extending the battery life. This is a very useful tool and very accurate. A great buy.

This li-po battery voltage checker is a very valuable tool for your rc helicopter. It can test the voltage of any battery anywhere. I checked it's accuracy against my VOM and it is right on. But the real value is when you use it as a low voltage warning system to protect your li-po's. You can set the voltage limit with the button on top of the unit. Then with a small velcro dot you can mount it, and plug it into the balance plug on your heli. When the set voltage is reached, the alarm will sound and you can land. You can hear the alarm across a large field. It will keep you from running your li-po voltage too low thereby extending the battery life. This is a very useful tool and very accurate. A great buy.

Save the LiPo battery with cut-off manually, when this device alarm. You can set the switching level for arming from 2.7V to 3.8V step 0.1V... Display voltage of any cell, and the total voltage of battery. The buzzer is loud, you can hear good from 100-200m on electric planes, and you can hear the overdischarged receiver battery alarm on gas/glow plane.

Save the LiPo battery with cut-off manually, when this device alarm. You can set the switching level for arming from 2.7V to 3.8V step 0.1V... Display voltage of any cell, and the total voltage of battery. The buzzer is loud, you can hear good from 100-200m on electric planes, and you can hear the overdischarged receiver battery alarm on gas/glow plane.

Save the LiPo battery with cut-off manually, when this device alarm. You can set the switching level for arming from 2.7V to 3.8V step 0.1V... Display voltage of any cell, and the total voltage of battery. The buzzer is loud, you can hear good from 100-200m on electric planes, and you can hear the overdischarged receiver battery alarm on gas/glow plane.

It's a great little thing that can be used to monitor your battery level and can be attached directly on your heli so that you can know the actual battery level on flight. Very cheap from Banggood, just one week to reach my home in envelope. Good job Banggood for the fast service.

It's a great little thing that can be used to monitor your battery level and can be attached directly on your heli so that you can know the actual battery level on flight. Very cheap from Banggood, just one week to reach my home in envelope. Good job Banggood for the fast service.

It's a great little thing that can be used to monitor your battery level and can be attached directly on your heli so that you can know the actual battery level on flight. Very cheap from Banggood, just one week to reach my home in envelope. Good job Banggood for the fast service.

These are the best little insurance package you can buy. Velcro this to your heli plug in the balance plug and set it to beep at you desired voltage. when you fly it will emit a very loud beeping when the voltage level is arrived

These are the best little insurance package you can buy. Velcro this to your heli plug in the balance plug and set it to beep at you desired voltage. when you fly it will emit a very loud beeping when the voltage level is arrived

These are the best little insurance package you can buy. Velcro this to your heli plug in the balance plug and set it to beep at you desired voltage. when you fly it will emit a very loud beeping when the voltage level is arrived

Simple and reliable. Protects the Lipo against deep discharge and your heli from crash on battery run out. The alarm is loud enough to warn you from hundreds of meters.

Simple and reliable. Protects the Lipo against deep discharge and your heli from crash on battery run out. The alarm is loud enough to warn you from hundreds of meters.

Simple and reliable. Protects the Lipo against deep discharge and your heli from crash on battery run out. The alarm is loud enough to warn you from hundreds of meters.

cheap but good quality... does have loud buzzer and shows cells individually . you can set low voltage alarm as well. worth to have.

cheap but good quality... does have loud buzzer and shows cells individually . you can set low voltage alarm as well. worth to have.

cheap but good quality... does have loud buzzer and shows cells individually . you can set low voltage alarm as well. worth to have.

The nice feature is you can select the Voltage threshold between 2.7 and 3.8 volts in 0.1 volt steps. Set to 3.5 volts, it warns me that I have one minute remaining to bring down my helicopter. Very good value for the price.

The nice feature is you can select the Voltage threshold between 2.7 and 3.8 volts in 0.1 volt steps. Set to 3.5 volts, it warns me that I have one minute remaining to bring down my helicopter. Very good value for the price.

The nice feature is you can select the Voltage threshold between 2.7 and 3.8 volts in 0.1 volt steps. Set to 3.5 volts, it warns me that I have one minute remaining to bring down my helicopter. Very good value for the price.

I have seen the same thing sold for US $19.00.This is exactly the same but with a very, very small price tag.I use it to check the voltage of my batteries.Also used as an alarm is one of the best reasons to have.US$3.11 with free postage???????? They are giving it away. The postage cost more than the price.

I have seen the same thing sold for US $19.00.This is exactly the same but with a very, very small price tag.I use it to check the voltage of my batteries.Also used as an alarm is one of the best reasons to have.US$3.11 with free postage???????? They are giving it away. The postage cost more than the price.

I have seen the same thing sold for US $19.00.This is exactly the same but with a very, very small price tag.I use it to check the voltage of my batteries.Also used as an alarm is one of the best reasons to have.US$3.11 with free postage???????? They are giving it away. The postage cost more than the price.

good price alarm battery, display more information if use button.

good price alarm battery, display more information if use button.

good price alarm battery, display more information if use button.