Remaining Battery always 100% at start


No matter how much voltage the battery I connect, the FC always interpretate the battery is fully charged. There is any way to calculate that battery porcentage from the input voltage? For example, Im using 6S battery, so the max voltage will be 25.2, that way if I plug a used battery, with 23V, FC could know that is not a fully charged battery.


I believe the percentage shown goes off of the mAh used which is why it always sets to 100 at start, I don’t think there is a way to base it off voltage but I could be wrong. I usually just fly my copters and try to get them back on the ground before the battery reaches 21.5v

Capacity is based on batt capacity parameter, calculating capacity spent using current sensor.
Voltage is not directly translatable to capacity, it depends on battery temperature,load, battery health.

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This behavior is by design. Its not up to a piece of hardware to “know” anything.

As the owner/builder/pilot of this aircraft it is YOUR responsibility to know the battery status.

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Thanks to everyone! Sure I know the porcentage decrease because the amps use, and we as pilots have to know the battery status. But when you sell a drone to a customer, for them is hard to understand a used battery shows 100%

We will have to wait until smart batteries start to show up in the mainstream market for custom drones. At that point we will have percentage shown when plugged in.

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Thanks! Im clear now!

Then tell 'em for crying out loud. Just explain it to 'em.

The irony here is if you are the one selling the drone, why did you have to ask us? You should have known the answer already.

Just to talk a bit about smart batteries, they would be very handy to me too. Sometimes we are out at the field doing some work and some days we have 15-20 battery sets rotating on the aircraft, on the chargers and so on. It happened to me to load the aircraft with a discharged battery.
To avoid any prob i enabled a parameter called ARMING_VOLT_MIN. It is the minimum voltage that will let you arm the vehicle. So if you fly with 6S set it to 24,8-24,9 and you’ll be sure that if the aicraft arms the battery is full. Obviously if you disarm with half battery left and you want to arm again, the system won’t let you do it.
In my case when we take off we never land before the battery is discharged so for me is perfect.

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As the saying goes, you got heist by your own petard. What you really need is to put ONE person in charge of battery management.

Here’s another tip for ya: Get a radio (like a Taranis) that with the appropriate hardware and software (Either Flight Deck or Yaapu ) will give you your current battery status at a glance.

I was an early adopter of Flight Deck, and I have also used Yaapu. You don’t need any stinkin’ smart batteries, or fancy timers, or custom parameters. The LUA scripting does it all including verbal call outs of remaining battery capacity, as well as battery low and battery critical alerts.

ArduCopter already has a parameter set that will prevent arming below a set voltage. Its called the Low Battery Failsafe.

Honestly, if you ask me, I think you are blaming hardware and software for something that humans are doing, or not doing.

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I am the one that charges battery and looks over the aircrafts flying. At my charging station i have a monitor with remote telemetry of all the aircrafts flying, not a taranis but a station with a dedicated monitor for every aircraft. We have 3-4 aircrafts flying at the same time and some days i have to look over 15-20 battery packs to manage.
My point of view is that smart batteries would make my life easier.
The parameter i use i think it is a bit more customizable and easier for my job. ARMING_VOLT_MIN has been available since 3.6.
I am not blaming anything i just don’t pretend to teach people how to do things, i just tell my experience from wich people may or may not learn something or get a new point of view.

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That is a very good tip (ARMING_VOLT_MIN). I will set this parameter up on my craft. I made a mistake a few months ago and accidentally put a used battery into my craft before a flight. And like an idiot i failed to notice the voltage on my osd. This resulted in the craft coming down 3 fields away. This highlighted a couple of things for me - first, be more careful with my battery management, and secondly never skipping the obvious when doing pre-flight checks! I was very embarrassed to make such a stupid mistake. Setting a parameter for ‘ARMING_VOLT_MIN’ will at least insure i do not make such a basic and stupid mistake again.

Sounds like the perfect solution when flying my larger 6S powered Hex, once i have taken off i never normally land until the battery is low anyway, so should not cause a problem with preventing arming when the battery is only slightly depleted. Or if i do need to make several flights with one battery, say for tuning or testing purposes it will not take much to change the parameter.

Thank for highlighting the ARMING_VOLT_MIN parameter, i did not realise it was there.