Mauch battery sensor issue with battery percentage always going back to 100%

ArduCopter Copter 4.0
1

I am using Copter 4.0.2 with the Mauch PL Sensor (200A) and I have set up the power info in Mission Planner and it seems to work fine on fully charged batteries. I am getting amp draw, mAh consumption and voltage numbers and the battery percentage will start to go down from 100% as I am flying.

The problem I am having is after flying for say 10 minutes and my batteries are about 50%, I land and unplug the batteries, but when I plug the same batteries back in the battery percentage goes back to 100% on the screen, even though the batteries are now at roughly 50% left and the voltage it is showing in Mission Planner is correct.

Any idea on why this is doing that and how I can fix it? It seems to be only going by mAh consumed and as soon as you turn it off and plug back in the mAh goes from 8000 mAh to 0 and will say 100%, which is completely wrong.

Thank you.

2

The percentage shown in Mission Planner is based on mAh consumed related to whatever the battery capacity parameter is during the power cycle of the drone, therefore unplugging the batteries resets the percentage.
You would need some type of smart battery for mission planner to keep track of the percentage after unplugging and plugging back in.

3

Well, that stinks. If I am not mistaken I thought when I used the PX4 software if you unplug and replug the same packs back in it will adjust the percentage accordingly of how much you have used it.

When you say smart battery, is this some type of special battery? Sorry, I am not understanding.

4

Yes a smart battery would be a specific type of battery, they usually have some sort of microchip installed internally that monitors battery parameters and provides them to their charger or a flight controller. I don’t believe there is any way to do this with base PX4 or Ardupilot and standard LiPo batteries

5

Yes, a smart battery has some built in electronics that measure the real battery capacity and track the number of charging and discharging cycles and other stuff.
something like: https://www.hackster.io/news/batmon-removes-ordinary-drone-batteries-limitations-for-increased-performance-958c3a6f355b

http://skymul-5867719.hs-sites.com/kickstarter-for-drone-battery-smartification?hs_preview=CTFnqckL-22578881645&ecid=&utm_campaign=Kickstarter%20Batmon&utm_source=hs_email&utm_medium=email&utm_content=2&_hsenc=p2ANqtz-9XcL3FxjenUFxt7CKAHKr5THdkkH60DLBIkQX52vCu-XgSc2-Y4072Q7HyUNt3WT5dDgCc-GdsGBgxDxXHbw2QbK2MHw&_hsmi=2

Just google it.

6

Apart from the smart batteries and projects like this:
https://discuss.ardupilot.org/t/batmon-kickstarter-add-smart-battery-monitoring-to-a-non-smart-battery/51650/50

The bottom line is you’ve got to know your own batteries and flight times. So if you’ve flown 5 minutes and then restart you drone, you’ve got to understand that you’ve only got (example) 4 minutes safe flight time left.
Make sure the battery failsafes are set and tested.

These are the paramaters I’d check:
BATT_ARM_VOLT (set so that you’re not arming with a low battery)
BATT_CRT_VOLT 3.5 x no. of LiPo cells
BATT_LOW_VOLT 3.6 x no. of LiPo cells
BATT_FS_CRT_ACT 1
BATT_FS_LOW_ACT 2
BATT_LOW_TIMER (test, depends how your batteries recover and how safe you want to be)
MOT_BAT_CURR_MAX (depends what your batteries and/or distribution system will supply)
MOT_BAT_VOLT_MAX 4.2 x no. of LiPo cells
MOT_BAT_VOLT_MIN 3.3 x no. of LiPo cells

1 Like
7

I think the simple way is to convert the battery Voltage to be Percentage. Anybody can advise how to do this?? Thank you…

8

The problem is that you cant reliably do that, or even come reasonably close - hence the requirement for smart batteries which will monitor their own usage.
There’s numerous discussions on all this already.

9

It’s not simple and you can’t do that. Pack voltage is not even a remotely accurate measure of mah consumed or remaining no matter how you slice it.

10

Ok, wish there was a better option. Thank you.