Mavic Pro Battery Mod

[chazz]

I have the voltage settings at minimum, but can't remember what it is. I routinely fly down to 3.4v under load before worrying about landing. What were you wondering? I can check some old logs.

I had mine turned down too but it didnt work with the Samsung 21700 batteries that tried using. These run lower volts and have pretty low current rating.

I was thinking that when the difference between the voltage and the current is too great it hits this mode..

Edit: so what i was looking for is the current and the Volts at the time it happens. Maybe the watts too

 

[lolo780]

I had mine turned down too but it didnt work with the Samsung 21700 batteries that tried using. These run lower volts and have pretty low current rating.

I was thinking that when the difference between the voltage and the current is too great it hits this mode..

Edit: so what i was looking for is the current and the Volts at the time it happens. Maybe the watts too

If you want to fool the ESC current sensing, hardwire directly to the pads beside the MOSFETs. You'll get motor idling/prop missing errors in flight but just like motor current errors on heavy draw they don't affect flight performance.
I didn't run that way long enough to see if there's any difference because I switched back to normal because I need the individual motor data correct to help optimize my setup. Once it's all sorted and I get through the 59k ft limit I may revisit this mod.

 

[chazz]

If you want to fool the ESC current sensing, hardwire directly to the pads beside the MOSFETs. You'll get motor idling/prop missing errors in flight but just like motor current errors on heavy draw they don't affect flight performance.
I didn't run that way long enough to see if there's any difference because I switched back to normal because I need the individual motor data correct to help optimize my setup. Once it's all sorted and I get through the 59k ft limit I may revisit this mod.

Yeeeah I'm not really there yet. I don't really want to adjust the actual current I just want to change what the program thinks about these settings. If that makes sense.

You don't have to make a special flight to do this but if on one of your flights that isn't working out or not going as expected maybe just let it auto land at the end. No big deal...

Edit: I have many other things to keep me busy with this thing when i can finally fly. I'm going to be grounded for a while its freezing around here..

 

[CyberNate]

Hmmm, Phxbird seems to have a drastically different battery calibration on his percentage vs voltage. His voltage shows 11.66V at 79% which is 3.886V per cell.


My 79% is 3.99V per cell:



If I continue to where mine is showing 3.89V per cell then I've covered 25K + 10K returning below for 35K to 11.66V:



Is my battery calibration way off? What voltage do you guys normally see at 79 to 80%?

 

[chazz]

mine runs like digdat0's...I compared his to mine once...3.88V at 79%

 

[CyberNate]

mine runs like digdat0's...I compared his to mine once...3.88V at 79%

Ok, then I'm getting good results. It is just this battery. I do see a huge difference in battery reading between this battery and another one I have. This one I can run for a couple minutes after it hits zero. So my results are better than they look.

Edit: The external capacity is based on voltage, so they have a lot more left than the percentage is indicating. I landed with 3.81V per cell. According to digdat0's video, i'd have 69% left in the tank! Wow. Better try my other internal battery tomorrow which is more like yours and Digdat0's.

 

[lolo780]

Battery percentage is based off the remaining mAh of the stock battery, independent of voltage. Temperature will play a part in the voltage you see, so just have to get to know your setup.

@chazz cold temps aren't as much of an issue if you insulate the batteries. On the up side, the dense air helps. I hovered a completely stock Mavic with Platinum props and a mediocre battery for 27:43 with the barometer showing about 1035.

 

[CyberNate]

Battery percentage is based off the remaining mAh of the stock battery, independent of voltage. Temperature will play a part in the voltage you see, so just have to get to know your setup.

Yeah, but the externals don't care about the mah of the internal. We can only monitor the voltage. So perhaps I used a bit more of my internal, but the externals have a lot left.

 

[lolo780]

Yeah, but the externals don't care about the mah of the internal. We can only monitor the voltage. So perhaps I used a bit more of my internal, but the externals have a lot left.

It would be nice to have voltage data from each pack. A good test is to drain to various percentages and then count mAh put back in to the externals.

 

[CyberNate]

It would be nice to have voltage data from each pack. A good test is to drain to various percentages and then count mAh put back in to the externals.

I have all my batteries labelled and this flight was my E battery. My D battery is so drastically different in it's calibration. On the D battery, my Mavic will start auto landing at 3 % which is below 3.4V already. On E autolanding comes deep into 0 percent. The entire curve is shifted between those 2 packs by a good amount. I think my D battery is even more optimistic than what you guys are seeing, as I remember BubbaBean graphed a few of our flights and that one was with my D battery and my plot vs percentage was far below the others. That's why I nose dived into the pavement, because I was paying more attention to percentage than voltage.

 

[chazz]

Ok, then I'm getting good results. It is just this battery. I do see a huge difference in battery reading between this battery and another one I have. This one I can run for a couple minutes after it hits zero. So my results are better than they look.

Edit: The external capacity is based on voltage, so they have a lot more left than the percentage is indicating. I landed with 3.81V per cell. According to digdat0's video, i'd have 69% left in the tank! Wow. Better try my other internal battery tomorrow which is more like yours and Digdat0's.

I wonder if there is a way to reset the mah on that battery. Maybe at some point drain that battery as much as you can or until the mav wont stay flying and then recharge it with the dji charger.

 

[CyberNate]

I wonder if there is a way to reset the mah on that battery. Maybe at some point drain that battery as much as you can or until the mav wont stay flying and then recharge it with the dji charger.

I run that battery to 3V regularly. I beat the crap out of my batteries.

 

[chazz]

I run that battery to 3V regularly. I beat the crap out of my batteries.

You use the dji charger? the aftermarket 5 in 1 starts charging at a higher current if that's what you use may cause this.

 

[lolo780]

I wonder if there is a way to reset the mah on that battery. Maybe at some point drain that battery as much as you can or until the mav wont stay flying and then recharge it with the dji charger.

If you guys want to try something interesting, charge it on the aircraft via the battery mod plug. You can see the cell voltage and capacity change.
Make sure to put a fan on the ac.

 

[CyberNate]

If you guys want to try something interesting, charge it on the aircraft via the battery mod plug. You can see the cell voltage and capacity change.
Make sure to put a fan on the ac.

;-) Yeah, you made me remove my fan! Great! Sucker gets so hot after like 2 minutes I have to switch it off. Worth it though!

 

[CyberNate]

You use the dji charger? the aftermarket 5 in 1 starts charging at a higher current if that's what you use may cause this.

Yes, use the 5 in 1. Perhaps you are right, that at higher current the voltage is shifted up and messes up calibration table. Thing is, I use it for all my batteries and they are all different.

 

[chazz]

If you guys want to try something interesting, charge it on the aircraft via the battery mod plug. You can see the cell voltage and capacity change.
Make sure to put a fan on the ac.

That IS interesting. How do you get around needing the balance lead plugged into whatever charger your using?

 

[CyberNate]

So airdata projection information is basically useless as it is going off the main battery percentage, which is based off mah used from internal. It has no clue about your externals which vary widely between battery types. There is no reference to cell voltage when it is projecting runtime.

 

[CyberNate]

Wow, 3.89V per cell after flying 52k. That's crazy.

 

[Phxbird57]

That's 2 batteries.

just remember did my first one with single battery. So the second flight was with both. Cyber next time stop at Wahlburgers pick me up one. It was not open when I was in Vegas yet.
And all so Cyber you are climbing twice what I am. That has to do some thing. Nice video.