Mavic Pro Battery Mod

action · Mar 31, 2018

Deadleg said:
I didn't change this parameter . . in fact I didn't know it existed!

Thank you for your reply,as soon as you select non-dji there is than a menu to choose how much cells

Deadleg · Mar 31, 2018

chazz said:
I've been working with these for a while and already did the 3s4p, 4s3p and now 4s4p. I've been working my way up to this. The 4s3p works with no compass errors as long as you position the batteries correctly and not under the compass but now the battery is getting too big and unless i make this a square wind resistant block that hangs straight down i see no hope for stopping the compass error. For example the attached pictures are both the same battery in different configurations and i got the compass error with the top one (black battery) and didn't with the bottom one (red battery). For these batteries anyway it seems its all about keeping them from under the compass...View attachment 34826 View attachment 34827

So it's good that you have flown successfully with 4s3p. Can you let me know what flight times you were getting? Do you have comparable results for forward flight and for hover? Sorry to go over old ground if you've posted all this before, but it's a long thread! Do you know how much power the 4s3p is using for hover, and the total weight of drone and battery?

There are not too many people doing these tests and I am very interested to compare test results. I have plotted the power curve for my first flight below. It needs about 130 watts of motor power, plus about another 10 watts to run the systems. I use the battery board from an original Mavic battery, but I think you only connect the power cables, so I'm not sure what you get in your log files. It would be interesting to find out . .

Deadleg · Mar 31, 2018

action said:
Thank you for your reply,as soon as you select non-dji there is than a menu to choose how much cells

This is an interesting question. At the moment it is only set to 3 cells, even though I am using 4. I am still using the Mavic battery control board, which is only designed for 3 cells. there are only 3 balancing connections on this board, so I can only monitor 3 voltages at most, but in practise, I can only see the voltages of 2 of the cells. But this gives a good enough feel for how much is left in the battery as a whole.

I have no idea what would happen if I switched the battery parameter from 3 cells to 4 cells, and at the moment I would rather not risk it, because everything is working well enough. Maybe I'll try it in the future . .

action · Mar 31, 2018

I tought about using it w/out battery board and place a Voltage meter attached to mavic so I can pan the cam down to see the actual voltage... just a imagination

Deadleg · Mar 31, 2018

action said:
I tought about using it w/out battery board and place a Voltage meter attached to mavic so I can pan the cam down to see the actual voltage... just a imagination

Yes, this is a good idea. I have already bought some miniature digital voltmeters from AliExpress for just this reason, but didn't have to use them because the board seems to work.

recoil · Mar 31, 2018

Is the inside if this batteries wet? Or is it just layers rolled? Has anyone tried to remove the metal from them and replace it with shrink wrap tubing or something like that? Perhaps a dumb idea.

Deadleg · Apr 1, 2018

recoil said:
Is the inside if this batteries wet? Or is it just layers rolled? Has anyone tried to remove the metal from them and replace it with shrink wrap tubing or something like that? Perhaps a dumb idea.

Check this out . .
Disassembly of cheap 18650 battery

whizzing arrow · Apr 1, 2018

Did anyone try put 2 DJI Mavic batterys in parallel.?

lolo780 · Apr 1, 2018

whizzing arrow said:
Did anyone try put 2 DJI Mavic batterys in parallel.?

View attachment 34872

How does that compare to stacking them horizontally? You can take the foam cell spacers out to gain a few mm.

whizzing arrow · Apr 1, 2018

lolo780 said:
How does that compare to stacking them horizontally? You can take the foam cell spacers out to gain a few mm.

The few mm do not bother me,what I'm interested in Has anyone tried this ?

Deadleg · Apr 1, 2018

whizzing arrow said:
The few mm do not bother me,what I'm interested in Has anyone tried this ?

It's nice that all 6 cells fit snugly inside. I think it's a great idea. Other people have left the standard battery in place and piggy-backed the dismantled battery on top, but your idea is more elegant. The 2 batteries together give 84 Wh, and with a combined weight of around 400-420 g, depending on what else you add, should give you about 35 mins hovering time. Are you going to use the intelligent battery board, or just run it as a power source without any telemetry?

whizzing arrow · Apr 1, 2018

Deadleg said:
It's nice that all 6 cells fit snugly inside. I think it's a great idea. Other people have left the standard battery in place and piggy-backed the dismantled battery on top, but your idea is more elegant. The 2 batteries together give 84 Wh, and with a combined weight of around 400-420 g, depending on what else you add, should give you about 35 mins hovering time. Are you going to use the intelligent battery board, or just run it as a power source without any telemetry?

Hello my dear fellow, combined weight is about 380g,yes exactly elegant and simple i am hoping to get 35 min flight time no i won't use the intelligent battery board just direct power source,yust ay need to figure it out how to make connections for the intelligent battery board so i can use the stock charger

chazz · Apr 1, 2018

Deadleg said:
So it's good that you have flown successfully with 4s3p. Can you let me know what flight times you were getting? Do you have comparable results for forward flight and for hover? Sorry to go over old ground if you've posted all this before, but it's a long thread! Do you know how much power the 4s3p is using for hover, and the total weight of drone and battery?

There are not too many people doing these tests and I am very interested to compare test results. I have plotted the power curve for my first flight below. It needs about 130 watts of motor power, plus about another 10 watts to run the systems. I use the battery board from an original Mavic battery, but I think you only connect the power cables, so I'm not sure what you get in your log files. It would be interesting to find out . .

I think got around 43min when the first cell hit 2.5V with the 4-3. I did one distance flight with it to 46000 and just landed when i came back. I don't know the power for hover and I don't remember the weight but if you figure the weight of what i'm using now is 1380grams it shouldn't be hard to figure out. I'm also using the battery board because i need cell voltage.

Deadleg · Apr 1, 2018

whizzing arrow said:
Hello my dear fellow, combined weight is about 380g,yes exactly elegant and simple i am hoping to get 35 min flight time no i won't use the intelligent battery board just direct power source,yust ay need to figure it out how to make connections for the intelligent battery board so i can use the stock charger

Ah well . . you could charge 2 batteries from one battery board, or you could charge one at a time. In either case you'll have to put it back together like you found it! In other words connect up the power leads and the balance leads as original battery. So, to charge 2 batteries together, wire them as a 3s2p and connect the balance leads across each pair of parallel cells . . then back to the battery board. Does that make sense?

Deadleg · Apr 1, 2018

chazz said:
I think got around 43min when the first cell hit 2.5V with the 4-3. I did one distance flight with it to 46000 and just landed when i came back. I don't know the power for hover and I don't remember the weight but if you figure the weight of what i'm using now is 1380grams it shouldn't be hard to figure out. I'm also using the battery board because i need cell voltage.

Thanks for that Chazz. 43 mins sounds about right. I can estimate the weight, but I can't calculate the power requirement from the weight because the lift efficiency drops dramatically with weight, so that's why I really need the FLYxxx.DAT log file, or the power graph from Assistant 2. Any chance you can post it or PM?

mavicpro1000 · Apr 2, 2018

whizzing arrow said:
Did anyone try put 2 DJI Mavic batterys in parallel.?

View attachment 34872

Yup,done this one! It's the best yet! Got 41 mins in the air! The cells sit nicely too without looking hideous. Pack temp stays around 26 degrees which is much better than the usual cased 50+ degrees which used to worry me!

whizzing arrow · Apr 2, 2018

mavicpro1000 said:
Yup,done this one! It's the best yet! Got 41 mins in the air! The cells sit nicely too without looking hideous. Pack temp stays around 26 degrees which is much better than the usual cased 50+ degrees which used to worry me!

i don't get voltage indicator and no percentage on the app if i go directly (without battery board)

whizzing arrow · Apr 2, 2018

For now the smart board need to be inside this system or there is no voltage reading (the main voltage ) so i will use one battery with sensing (smart board) and the second goes old fashioned way parallel.

whizzing arrow · Apr 2, 2018

this setup is not working properly! the battery leds indicate battery charge level and you can turn battery off or on but it not sending voltage to pins.

whizzing arrow · Apr 2, 2018

I do not believe i fried one of the ICs or damaged when ay took it apart. What i believe is that dji put some sort of protection. the board has 24/7 power to the ICs if you disconnect the power it goes in som safe mode and it wont send power to the output pins the function for on or off works the led indicators for battery level works there is voltage on the rx and tx pins.