Mavic Air Batteries

[Jarlath]

According to the specs on the back casing of the battery, these are 3 cell LiHV batteries. (LiHV or HVLi = High Voltage Lithium Polymer)
LiHV can be charged to 4.35v per cell vs. standard LiPo's 4.2V (Nominal Voltages per cell are 3.85 and 3.7V respectively as well)

I know there are a ton of B6 balance cables which are online, but I am wondering if they truly are balance chargers or does the "intelligent" battery control the balancing?
Does anyone have a Pin Out layout for the Mavic Air Battery?

I ask as I do RC Cars and Trucks using Lipo and when you over discharge a battery, most "balance" chargers refuse to charge them when below a certain threshold. The un-official repair is to slowly charge the battery's main output as a NiMH battery at very low amperage until the overall voltage in the cells has increased above that threshold for the balance charger to take over.

I did find this online, but it does not say if all 4 +ve pins get 13V input/output?
All 4 grounds are supposedly tied together (may as well be one pin), but are the 4 +ve connections separate or 3 cells (each at 4.4V max) and one combined output (11.55V)? Or are the 4 +ve each at combined output?
If the latter then the "Intelligence is doing the balance charging and you would need to pry the whole GD thing apart to correct the cell V balance externally...

Again As I stated in my intro on the forum, I received my used Mavic with 2 dead batteries... Just wondering...

 

[old man mavic]

as you surmised the actual balancing is done by the electronics in the battery itself it controls max charge level, balancing, low voltage cut off ,keeps a log of the no of charges, and individual cell voltages, and will do a slow discharge after a set time if left fully charged, this is why they are so expensive compared to standard lipos, hence the term intelligent battery but they still suffer if misused and if punctured will go up in smoke like any other lipo

 

[Rayray]

"Up in smoke"...I like that!
I've had an MA for months, 3 batteries, and never paid attention to the batteries once I saw they would not be easily duplicated. And the print on them is so small...Just now my magnifying glass finds the maximum charge is stated to be 13.2 volts with nominal of 11.55.

Nowhere does it say LIHV but 13.2 (4.4 per cell) is above typical LIHV max voltage (typical LIHV max is 4.3 per cell). Indeed they are LIHVs. Mine do self-discharge, SLOWLY like all smart batteries I have. Never a problem with them.

As for getting 2 dead batteries with a used MA, this is part of the risk when buying used drones (or cars).

 

[Jarlath]

"Up in smoke"...I like that!
I've had an MA for months, 3 batteries, and never paid attention to the batteries once I saw they would not be easily duplicated. And the print on them is so small...Just now my magnifying glass finds the maximum charge is stated to be 13.2 volts with nominal of 11.55.

Nowhere does it say LIHV but 13.2 (4.4 per cell) is above typical LIHV max voltage (typical LIHV max is 4.3 per cell). Indeed they are LIHVs. Mine do self-discharge, SLOWLY like all smart batteries I have. Never a problem with them.

As for getting 2 dead batteries with a used MA, this is part of the risk when buying used drones (or cars).

Yup. Not a risk I was aware of with the DJI batteries (Yuneec's are not "Intelligent"). Well I now will have two Dead Batteries to tear apart and investigate. Maybe make an external balance plug to test the cells' IR and voltage levels.

 

[Jarlath]

Interesting... Finally dissected a dead battery... (Removed the cover anyways...)





There is a pair of power lines inside. but not to the power button. They are to the side mounted battery releases. Looks like they close/open a circuit when the battery is in removal position (either/both locking tabs pulled back).

 

[Deleted member 94047]

There is a pair of power lines inside. but not to the power button. They are to the side mounted battery releases. Looks like they close/open a circuit when the battery is in removal position

So if you remove a battery before powering it off, that should be OK? Not that I will try it.

 

[skyrex]

The wires to the release clips possibly for detection of improper seating of battery in craft? If not fully locked into position they would open or close a circuit to prevent takeoff?

 

[Jarlath]

So if you remove a battery before powering it off, that should be OK? Not that I will try it.

I doubt it. Likely an interrupt for when installing/removing the battery to prevent arcing across the Mavic Air contact pins. Or as stated, maybe a safety for ensuring a secure battery for takoff?

 

[Detritalgeo]

If you look at the charger block it has a very basic schematic of the pins.
Basically one side is positive, one side is negative and the middle 2 are for battery data feed (status, settings, firmware, etc..).

 

[Jarlath]

If you look at the charger block it has a very basic schematic of the pins.
Basically one side is positive, one side is negative and the middle 2 are for battery data feed (status, settings, firmware, etc..).

Yeah. I'm going to find out the polarity of the batteries (If they have any voltage left). Either through a simple LED test or my Multimeter. The larger opening on the board look to be the +ve & -VE connections for the individual cells. But who knows which ways are which...

 

[Detritalgeo]

There should be markings for the pos and neg on the board (of course) and continuity test should tell you the series routing..

I have used a hobby charger to get the cells back to a nominal resting voltage but there was a "permanent fail" condition in the battery control IC due to the under-voltage event. This flag can be removed from the chip using software but I can't justify the cost of the software.. For a 'revived' battery that will have degraded capacity.

Good luck! Let's hope the control board is still good.

 

[dawgpilot]

The wires to the release clips possibly for detection of improper seating of battery in craft? If not fully locked into position they would open or close a circuit to prevent takeoff?

This explains how the drone is able to give you the warning about an improperly installed battery. I had wondered how the drone was able to determine that since obviously it's getting power if it's able to connect and display that message.

 

[Jarlath]

So I got around to checking the voltages and polarity of the battery connections on the dissected Mavic Air Battery pack.



Polarity.
Position 1: +ve terminal for Cell 1
Position 2: -ve terminal for Cell 1
Position 3: +ve terminal for Cell 2
Position 4: -ve terminal for Cell 2
Position 5: +ve terminal for Cell 3
Position 6: -ve terminal for Cell 3

Tested the cell voltages:
Cell 1 at 1.362V
Cell 2 at 0.713V
Cell 3 at 1.895V
Measuring 3.968V across 1&6


So time to make and install a balance plug and individually charge each cell back up to 3.5V or so (at about 0.1A charge rate).

 

[Jarlath]

Well damned... I tried soldering some leads and wires to the "pads" but nothing stuck... Very annoying.

 

[Wabroli]

Well damned... I tried soldering some leads and wires to the "pads" but nothing stuck... Very annoying.

Well damned... I tried soldering some leads and wires to the "pads" but nothing stuck... Very annoying.

Hi, I opened my dead battery too and I find some tests and I find this connections:

Obs: The 56ohms resistor is my Idea to recharge The cells to wake up The battery.

This 2 FETS act like switches leading energy from The charger, (pins 7 to 10) to battery cells. So I think to use The resistor to bypass The switches

 

[Wabroli]

batteries charged up to 11.1 volts (I think that's the limit because it stopped charging )but it didn't work. I found an information that you need to erase through software the circuit that controls the battery charge in order to work, ie the solution it's not simple

 

[Detritalgeo]

If the cells are fine, then there may be a 'pf' (permanent fail) flag in the battery management IC. This can in theory be re-set using the SDA/SCL data lines and some PC software. This has been done for the phantom batteries and has been done for many years on laptop battery BMS chips but it's not free software.

 

[Thomas B]

So if you remove a battery before powering it off, that should be OK? Not that I will try it.

Not a good practice.
However, interestingly, I have inadvertently removed a battery that was still “on” and my video was still saved. Thanks for the smart battery DJI!

 

[zettler]

First post from new Mavic Air owner...

I just bought one on clearance from Wally World and now my mission is to find an extra battery or two.

Almost bought one for the Pro but read just now how they are incompatible.

My query is where can one buy an extra battery (or two) at a reasonable price?

For what I paid (fortunately) for my DJI, buying two batteries would almost double what I paid...

Anyway, sorry to interrupt for all I have done so far is open the box. Now I want to at least find one extra battery and whatever spare parts I ought to have on hand - just in case.

Thank you in advance for your counsel.

 

[BigAl07]

First post from new Mavic Air owner...

I just bought one on clearance from Wally World and now my mission is to find an extra battery or two.

Almost bought one for the Pro but read just now how they are incompatible.

My query is where can one buy an extra battery (or two) at a reasonable price?

For what I paid (fortunately) for my DJI, buying two batteries would almost double what I paid...

Anyway, sorry to interrupt for all I have done so far is open the box. Now I want to at least find one extra battery and whatever spare parts I ought to have on hand - just in case.

Thank you in advance for your counsel.

I don't think you can "judge" the cost of the battery against the phenomenal deal you got from Wally World. Just take the $$ you saved on the Wally Deal and use it to buy batteries from a reliable source. Don't skimp on the batteries . . . . They are a Single Failure Point....