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Hobby King Battery Monitor 3S

Hobby King Battery Monitor 3S

Hobby King Battery Monitor 3S
This unit will give a warning buzzer when the Lipoly pack drops below 9v.


Weight: 30g
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Price  $3.99

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 Customer rated
Total of 42 discussions.
DooGZ  78 points - 10/3/2015
detects all/total cells voltage, NOT individual cell, much better to add a diode or 2.
Skylanders  97 points - 3/9/2015
Useless! You should never run a cell below 3.2V!!! You should always land immediately when at 3.3V! If you discharge below 3V per cell and charge it later, puffing the battery will be a high risk! This is stupid, why are they selling this as a "safety" device? It is dangerous to trust this alarm. DON'T use it!
 anikeev 1410 points
Once it believes that voltage is too low (when I take-off my quad) the only way to stop buzzing is unplugging it and connect again. Absolutely useless. But I use 2S monitor for my car and it really helps.
faqcya  8 points - 11/17/2014
Isn't 9v way to low for a warning on 3s?
 mouchadino 562 points
if your lipo 3 s voltahe <=9v the buzer will be cry out :p
 faqcya 8 points
That's understandable. But again I ask isn't 9V way to low voltage for a warning on 3s? Shouldn't it be more like 10.2V? 3.4V per cell. This is the way I understand Lipos at least If you wait to 9v more then likely at least 1 of the cells will be less then 3V which is lower then the lowest voltage a cell should go. And you will destroy your batteries like that. Not to mention the fact that you're not going to even be able to stop the voltage instantly if you did wait til it reached 9V. Could somone please clarify this for me.
 MistyFuture 14 points
hi there, i bought it before and it sounds not too much, so i am not using it anymore because you cannot hear it when the plane or heli on sky.. you should buy the other one with two speaker..
 Ivars 2 points
I don't know about5 anyone else, but my q
 Ivars 2 points
Sorry, hit enter at wrong time... anyway, my quad will fall to ground way before the battery drops to 9v (somewhere in the neighborhood of 10.5V), so I question the usefulness of a monitor that only signals at 9V.
Sergeev  2 points - 9/23/2014
The monitor controls the entire battery or each element separately?
 anikeev 1410 points
It controls the entire battery.
Dmitry  20 points - 5/20/2014
What dimensions of this device L x W x H (mm)?
 anikeev 1410 points
PCB lengh is 26mm, but with speaker it's 30mm, W is 11mm and H is 1 or 2mm just PCB and H with speaker is 11mm. Hope that helps.
Customer Reviews
Overall Rating
53 thumbs up!
Works well. Nice to know when your battery is running low.
This is a very cheap insurance to protect your large investment into the plane and batteries.
Keep you, your plane and spectators safe.
You do need to solder your own connectors it comes as you see in the picture with no manual. Just solder the 2 wired to the two outside pins on the connector matching plus and - and you are ready to go.

It is of a limited value if you have an EDF plane or fly in the area where EDF plane is preset. The signal is just no loud enough to pick up over the roar of the EDF. You'll have to do a no power, low altitude fly-by to pick up the siren.
The warning LED is small and unless you fly in the evening or have eagle eyes you will not see it in flight unless doing a slow fly-by.

It is very good for small GWS or 3d Planes that fly quiet or very close to the pilot.

I also found the plug to be fragile and it broke with in 3 uses so I just plug the wires directly into the battery.

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Overall Rating
Sam I Am
41 thumbs up!
This is a great item. It works great and is at an amazing price. I would defiantly recommend this to everyone. It is a must have for all hobbyists. No one wants to lose their plane just because their batteries were to low. I did once and learned from my mistake. I bought this and it works great.

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Overall Rating
37 thumbs up!
Good lipo monitor I have one on my every model. Why 4 stars only? Small differences in alarm level. But it's a must have for every LiPo user

3 comments. Reply..

Overall Rating
Panayotis Pantazopoulos
28 thumbs up!
In my opinion this is a good accessory for all the electric slow fly planes and 450 size helis.
You can see and hear the warnings, so you know when you have to land.
The led is not very very bright and the buzzer not so loud, but for the price is the best you can have. For helis and foam planes i think is best.

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Overall Rating
Blue Angel
21 thumbs up!
The Maxpro Battery Monitor is a good device to monitor your lipos.
But i think it is a little bit too quite to use it in an airplane or helicopter. So, you have to fly near to hear the beeps.
I uses this monitor in series with an diode to monitor my 3s transmitter lipo. So it beeps at about 10,5 V.

There is a led on the monitor.
above 11,0V its lighting blue
10,0-11,0V its blinking blue
under 10,0V its lighting red
under 9,8V its beeping and blinking red

current draw is really small, about 5mA.

so, because of the not so loudly buzzer => 4 stars

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