Low Voltage Cutoff Switch - Servo City - RC Groups

Low Voltage Cutoff Switch - Servo City

Another RC solution from the folks at Servo City

Splash

Voltage...It must be cutoff!!

Whenever I think of Servo City I envision a whole city built entirely of servos. It's glorious! Here is another product brought to you buy this company that has helping us in our hobby for years...

Protect Your Lipos

It's important to protect your LiPo batteries from being drained below 3V/cell. Servo City's Low Voltage Cutoff Switch does just that.

This switch has 3 modes;

  • 1S
  • 2S
  • 3S

It passes the voltage on from the battery to the load (motor controller, ESC, servo controller, light, etc.) until the battery meets the cutoff voltage.

Whether you are powering a microcomputer like a Raspberry Pi, a microcontroller like an Arduino or an RC vehicle, our Low Voltage Cutoff Switch takes away one of the main challenges of working with LiPo batteries.

Specs

  • Product Weight - 0.35 oz
  • Max Voltage - 15V
  • Max Current (Peak) - 15A @ 3V | 20A @ 6V | 20A @ 9V
  • Max Current (Continuous) - 10A @ 3V | 15A @ 6V | 15A @ 9V
  • Current Drain (ON - 3mA @ 3V | 8mA @ 6V | 15mA @ 9V
  • Current Drain (OFF) 1mA @ 3V | 2.5mA @ 6V | 5mA @ 9V

Learn More

For pricing and the buy link head over to Servo City.

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Dec 01, 2017, 02:08 PM
Registered User
I just attach a battery monitor to my battery and carefully observe the voltage. Such a device is actually quite dangerous: if you lose motor power, you might stall your aircraft and crash. Sure, you will have protected the Lipo by not going below 3v per cell, but your aircraft (which likely costs more than the battery) is gone. Worse still, this particular one seems to remove power even from the servos, which is just plain unsafe. If you're flying and you lose complete control, who knows where the aircraft could end up? And what if it goes through a car window or hits someone? Yeah, this sounds overly sketchy just to protect a battery.
Dec 01, 2017, 02:28 PM
Registered User
Quote:
Originally Posted by FTfan
I just attach a battery monitor to my battery and carefully observe the voltage. Such a device is actually quite dangerous: if you lose motor power, you might stall your aircraft and crash. Sure, you will have protected the Lipo by not going below 3v per cell, but your aircraft (which likely costs more than the battery) is gone. Worse still, this particular one seems to remove power even from the servos, which is just plain unsafe. If you're flying and you lose complete control, who knows where the aircraft could end up? And what if it goes through a car window or hits someone? Yeah, this sounds overly sketchy just to protect a battery.
Yea after reading the description, I came away with a similar conclusion. I might be missing something, but how is this really useful for RC hobbyists (on models)? Complete loss of power when it hits low voltage seems like a bad idea. I'd rather destroy a lipo any day...again I'd like to know if I'm missing something...
Dec 01, 2017, 02:46 PM
Registered User
DaveNH's Avatar
From the description it makes no sense at all to use one of these, as was posted above I'd much rather lose a lipo than the plane. If it does in fact cut all battery power, who thought this was a good idea?
Dec 01, 2017, 04:03 PM
Frankenstein recycled packs
rampman's Avatar
Agreed BUT I had to jump start three 2S lipo's this week for my son's co-worker who has a kid that runs his RC truck down to 2.x volts / cell. he is 4 or 5 years old.

For RC cars/trucks/boats I feel this is a GREAT idea and will pass this along to my buddies with kids and cars.

Rick
Dec 01, 2017, 05:19 PM
Registered User
Quote:
Originally Posted by rampman
Agreed BUT I had to jump start three 2S lipo's this week for my son's co-worker who has a kid that runs his RC truck down to 2.x volts / cell. he is 4 or 5 years old.

For RC cars/trucks/boats I feel this is a GREAT idea and will pass this along to my buddies with kids and cars.

Rick
Cars and trucks, yes. Boats... well, maybe not . I guess one wouldn't be too happy to fish the boat from the middle of the lake.

Does he use one of these:
https://www.readymaderc.com/store/in...oducts_id=2598 ?
Dec 01, 2017, 05:39 PM
Registered User
DaveNH's Avatar
Quote:
Originally Posted by rampman
Agreed BUT I had to jump start three 2S lipo's this week for my son's co-worker who has a kid that runs his RC truck down to 2.x volts / cell. he is 4 or 5 years old.

For RC cars/trucks/boats I feel this is a GREAT idea and will pass this along to my buddies with kids and cars.

Rick
Good point, I wouldn't use one on a boat, but probably a good idea for ground vehicles.
Dec 01, 2017, 06:47 PM
Frankenstein recycled packs
rampman's Avatar
Quote:
Originally Posted by FTfan
Cars and trucks, yes. Boats... well, maybe not . I guess one wouldn't be too happy to fish the boat from the middle of the lake.

Does he use one of these:
https://www.readymaderc.com/store/in...oducts_id=2598 ?
No. Kid is 4 or 5 years old. My guess is that is too much hassle and too much for him to understand.
Be the time pops got home on Tuesday the kid had 2 packs reading under 3 volts. Also, that cell checker will not read cell V if much under 3.0 volts.

Rick
Dec 01, 2017, 08:16 PM
Registered User
Quote:
Originally Posted by DaveNH
Good point, I wouldn't use one on a boat, but probably a good idea for ground vehicles.
Yep ground vehicle makes sense...
Dec 01, 2017, 09:28 PM
Registered User
Also, don't most ESC:s have a low voltage cutoff feature? Some can even be programmed to reduce power to give a warning before shutdown. And servos will still be operational so it' s at least possible to glide down in case of a plane.

On helis and multis a battery monitor of some kind or telemetry is of course the only sensible option. Even a timer will do but no "hard" cutoff as losing power mid-flight will almost certainly cause a crash.

But for ground wehicles and non-RC applications sure. This would be just the ticket for the kid's truck if the ESC does not have a cutoff feature. I personally would not allow a child under 10 years to handle LiPos unattended though.
Dec 03, 2017, 07:23 PM
Professional UAV Services
Redemptioner's Avatar
Well it depends on what you are using it for, say you are using a Lipo to charge other batteries, great little device to prevent you killing the main lipo, would be better though if you had direct control over the exact cut out voltage and the time it needs to exceed that voltage before cut off.
Dec 08, 2017, 05:28 PM
AMA 1242

Batteries


Quote:
Originally Posted by Redemptioner
Well it depends on what you are using it for, say you are using a Lipo to charge other batteries, great little device to prevent you killing the main lipo, would be better though if you had direct control over the exact cut out voltage and the time it needs to exceed that voltage before cut off.
I have not seen any in a long time, but there was a unit out years ago that hooked to the balance tap & esc . It had a adjustment on for low voltage on cells. Would cut esc out on motor only. I believe it was called a CELL PRO or cell ck. .
Last edited by jerseyhank; Dec 08, 2017 at 05:29 PM. Reason: a
Dec 08, 2017, 05:40 PM
ancora imparo
jj604's Avatar
Hm.... that should be extremely simple for the DIY crowd to adapt from one of the LiPo cell checkers that have adjustable voltage. Use the buzzer output to drive a transistor across the ESC signal lead to ground.

Connecting the signal to ground stops the control pulse and stops the motor.
Dec 09, 2017, 06:36 AM
AMA 1242
Best part about this thing it was just a little larger than a postage stamp. I have one I will have to hunt it up.
Dec 09, 2017, 07:18 AM
ancora imparo
jj604's Avatar
Gearbest sell this version of the typical 1-8S LiPo alarm for about 2 bucks with free delivery.

https://www.gearbest.com/multi-rotor...8aAppCEALw_wcB

I suspect it is trivial to pick off the Buzzer drive and add a transistor or MOSFET to act as a shorting switch across the throttle signal.

Hmm... I feel a project coming on - as though I didn't have enough already.

John


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