The PixHawk along with Mission planner allows us to set battery thresholds and we can make a Quad or plane to do RTL, land etc. if the battery voltage drops below predefined thresholds.
I am wondering if there is an external battery cut of a system that can stop the battery from draining below certain per cell voltage to maximize the battery life for 4S to 6S + Lipo's?
I saw one device on eBay called "Lipo shield"
Not ordered it yet, but wondering if anyone has used any other devices in the past with similar feature functionality and designed for 6S @ 10,000 mAH and higher.
You'll have to explain how a soft cut off is not going to result in a crash with a multi :) I've used Lithium Ion cells that has protection circuits built in, but it's a hard cut off.
Doesn't sound like good idea to me. Why would you want a device to cut power while the aircraft is in flight?
Here is the snippet from the users manual. It doesn't cut off power immediately.
LipoShield is a low voltage cutoff device which enables any ESC to be used with lithium battery packs. It installs easily between your receiver and ESC and provides a reliable 3.0V per cell soft cutoff to prevent over-discharge damage to your expensive lipo packs.
LipoShield is a soft cutoff, so it is appropriate for any plane, even 3D types. The soft cutoff gradually reduces power to the motor allowing you to make a controlled landing.
When you notice the aircraft becoming sluggish, it is time to bring it in. The cutoff can be reset by throttling down to zero, then throttling back up. This enables a "go around" to prevent emergency landings and long walks to retrieve your plane.
LipoShield automatically detects the number of lithium cells in your battery pack at power-up and sets the appropriate cutoff voltage. It then continuously displays the detected number of cells by blinking the "Cells" LED. LipoShield works whether you're running a BEC built into your ESC, a separate BEC such as ParkBEC or even a receiver pack.
LipoShield uses a microcontroller to modify the throttle signal sent from the receiver to the speed control. As a result, it works equally well with older ESCs that have no lithium cutoff settings, and new ESCs that have unreliable cutoffs. It will even work in conjunction with another soft cutoff built into your speed control.
LipoShield works equally well with brushed or brushless ESCs.
LipoShield is intended for aircraft with 0-100% style one direction only throttle.A future product will be aimed at cars.
|Input voltage||1S to 12S Lithium or Lithium Polymer|
|Weight||0.14 oz. (3.5g)|
I don't know what brand/type of ESCs you use, but every ESC I have has an LVC. I use the LVCs for my helis because I never fly them beyond LOS, and even if the LVC cuts in, I still have enough control to land.
My multirotors are a different story. I turn the LVCs off completely. I have telemetry to my X9E, and the Pixhawk battery monitors have been calibrated by yours truly so the charged current vs logged total current used is with +- 100mAh.
When my X9E says I have 30% battery remaining I know I have 30% battery remaining. And, based on extensive flight testing, I know when each aircraft will RTL on low battery to within a few seconds.
So, not only do I know for a certainty that my aircraft are safe to fly, I know exactly how long each of my aircraft can fly which makes mission planning a snap.
But hey, if you feel better with an external LCV, then by all means use it...
@Clifton Hipsher - Good points.
I think the use of this device will come handy for fixed-wing aircraft with no FC of any kind but using LiPO battery and brushless motors with a simple radio setup.
We are working on developing some fairly long range drones. (We have FAA special clearance). We are talking 80 KM range, with live video feed via 4G/5G LTE. So we are simply exploring options and trying to figure out a complete fail-safe system. The Drone is hybrid of gas and brushless motors to achieve long range and some proprietary battery swap system while the drones doing waypoints.
PixHawk doesn't monitor individual cells inside the LiPO battery which has caused problems in the past. Sudden battery death and LiPo battery losing its charge beyond it can be recharged.
I have found one company that has developed a new PixHawk voltage regulator monitoring system
Very interesting product line for sure.