Mavic Air 2 44:20 min / 19.5km battery mod

[szakeetm]

I did a DIY battery mod experiment.

I first ordered 3 of these cells from Aliexpress (credit to @lee82gx for the advice!).

Then I opened a stock battery, and after equalizing the voltages, soldered them parallel:





Apologies for the makeshift case, I will make a nicer one once the protoyping is over.

The battery can charge with the stock charger, and balances cells normally.

The first test was hover indoors (41.5 minutes):



Then I went out for a flight, 44.5 minutes (vs. stock 30-31 minutes real-life):


Please note that the battery BMS will not auto-learn the double capacity, it will indicate that the battery is empty near 50% charge. Your drone will throw critical low battery warnings, reduce power and will try to descend and auto-land after a while (which you can counter-steer with the stick).

Is this mod for everyone? Not really, as it entails some work, risk and low battery warnings. Can you add nearly 50% more flight time with a 25$ investment? Absolutely.

 

[lee82gx]

nice, its a bummer that it will not learn or adapt to new capacity but that can only be expected. as a vendor i will not program my bms to do so, as there is no economical interest. as i can summarize as of today, 17 July 2022, you'd still need a password to unlock the bms to rewrite the capacity, via TI tools or other paid, hacking methods. shame.

 

[Capt KO]

Don’t believe it’s a long term solution. The constant extra load will wear out the motors prematurely. I carry loads with my drones but it’s only temporary as the loads are dropped during flight. It will obviously void any warranty as it will be recorded in the logs. But, to each his own. Good luck.

 

[lee82gx]

nice, its a bummer that it will not learn or adapt to new capacity but that can only be expected. as a vendor i will not program my bms to do so, as there is no economical interest. as i can summarize as of today, 17 July 2022, you'd still need a password to unlock the bms to rewrite the capacity, via TI tools or other paid, hacking methods. shame.

By the way, if you did get the CP2112 USB adapter, perhaps you can contact this guy :

TRB

trb.patboonlab.co

I'm not completely sure but I think there is a possibility to use his software to fully unlock the bms and gets you the ability to reprogram the battery capacity.

Last time, I talked to him via email and he mentioned he can consider a trial license for a short period (less expensive) to unlock a few battery bms'es. Otherwise, EV2400 (cloned china copies) + his TRB software license is still prohibitive to a single use DIY'er.

Rgds
Lee

 

[szakeetm]

Thank you Lee.

I did order the CP2112, it's on its way from China.

I contacted TRB to send in my battery (France to Slovakia), reprogram it and send back, but the two-way shipping and reprogramming cost is similar to the Ev2400 clone + TRB license. Also, in theory the post doesn't allow shipping raw lithium cells.

I managed to disable the drone's autolanding with Drone-Hacks, I'm experimenting to disable the power reduction. If it's unusable, I'll probably go EV2400+TRB, it's a pity that the license is time-based, not one-off.

 

[lee82gx]

Thank you Lee.

I did order the CP2112, it's on its way from China.

I contacted TRB to send in my battery (France to Slovakia), reprogram it and send back, but the two-way shipping and reprogramming cost is similar to the Ev2400 clone + TRB license. Also, in theory the post doesn't allow shipping raw lithium cells.

I managed to disable the drone's autolanding with Drone-Hacks, I'm experimenting to disable the power reduction. If it's unusable, I'll probably go EV2400+TRB, it's a pity that the license is time-based, not one-off.

Did you try and plead with him to allow a one time fee access? Or a few day access? That was what he propose for me the last time.

Did you also ask whether the CP2112 is enough? I never got around to asking about this. Perhaps CP2112 + TRB short license if feasible is the least painful economically.

 

[mattcaz]

I know this won't be a popular response but as I sat here reading this I kept asking myself 'WHY'. I have 6 batteries if I need them and swapping out isn't an issue. I guess maybe it's a "Just want to see if I can" modification.

 

[Conservative Nihilist]

I know this won't be a popular response but as I sat here reading this I kept asking myself 'WHY'. I have 6 batteries if I need them and swapping out isn't an issue. I guess maybe it's a "Just want to see if I can" modification.

In parts of the world where FAA and CAA regulations don't apply, people like me enjoy flying their drones well beyond the reach of the controller's signal range, under the fully autonomous control of Litchi's superb waypoint planning facility available via the Litchi Mission Hub, a freeware product that enables flight paths to be planned and saved using a desktop computer which can, in turn, transmit such saved flight plans via Wifi to the smart device I use for drone flying.

For example, given that the Mavic Pro 1 and the Mavic Pro 2 deplete their batteries down to 15% after 21 and 23 minutes of flight time respectively, before then defaulting into a forced auto-land, any improvement in battery duration would translate to more miles covered per individual flight. Currently, my Mavic Pro1 and Mavic Pro Platinum can only manage a 6.1-mile round trip flying at 20 mph before defaulting into low-battery RTH and making a beeline for home.

Ever in search of a means to launch longer flights, I scour the internet regularly in the hopes of one day finding an after-market extra-capacity battery that would enable my Mavic Pro1s or Phantom 3 Standard to exceed that 6.1-mile round trip waypoint mission distance limitation at which low battery RTH kicks in for all my drones with their stock batteries.

 

[malinkigoosik]

I’ll take your 44 and raise you 16. I used mini 3 pro plus cells to make a 2P3s config. Battery is 7700mah and 11.07v nominal and 12.75v max. I also reoprogrammed the bq40z307 bms to match the chemical id and parameters of the new cells.

It started to rain so I couldn’t conclude my test, but I’ll post results tomorrow.

 

[Mavicrebel123]

Oddly, the web specs on dji say a mini three pro battery is 7.38 V. Wouldn’t that make it a 2S and not a 3S?

 

[oxolot]

I did a DIY battery mod experiment.

I first ordered 3 of these cells from Aliexpress (credit to @lee82gx for the advice!).

Then I opened a stock battery, and after equalizing the voltages, soldered them parallel:

View attachment 151875
View attachment 151876
View attachment 151877

Apologies for the makeshift case, I will make a nicer one once the protoyping is over.

The battery can charge with the stock charger, and balances cells normally.

The first test was hover indoors (41.5 minutes):



Then I went out for a flight, 44.5 minutes (vs. stock 30-31 minutes real-life):


Please note that the battery BMS will not auto-learn the double capacity, it will indicate that the battery is empty near 50% charge. Your drone will throw critical low battery warnings, reduce power and will try to descend and auto-land after a while (which you can counter-steer with the stick).

Is this mod for everyone? Not really, as it entails some work, risk and low battery warnings. Can you add nearly 50% more flight time with a 25$ investment? Absolutely.

Hi. Did you eventually manage to record proper Qmax, EoC and Vmax values for this double-capacity value? What are they?

 

[szakeetm]

Hi. Did you eventually manage to record proper Qmax, EoC and Vmax values for this double-capacity value? What are they?

I did not invest in the end in the programmer tool and the software.
Vmax would be the same (4.4V), I measured 7350mAh capacity with an external load, the rest I don't know.

 

[AntF1551]

Oddly, the web specs on dji say a mini three pro battery is 7.38 V. Wouldn’t that make it a 2S and not a 3S?

he's using the internal cells of the battery. looks like 3 mini 3 pro batteries or they happen to match the size of the Air 2 battery cells.

The Mini 3 Pro is 2S 7.4V. (~7v-8.4v)

He has a 3S2P configuration. So its a 3S battery (11.1v). There's 3 pairs of cells wired up in parallel for the increased capacity and then the 3 cell stacks in series to get the correct 3S voltage.

You could technically make a 6S (22.2v) battery with that amount of cell's, it would just have 1/2 the capacity/(mAh) as the 3S battery's setup.

 

[Conservative Nihilist]

Even with my background in component-level electronics PC board repairs, I would be extremely nervous about soldering to Lipo batteries due to the risk of spontaneous ignition with my face just inches from the batteries.

I'd been following this thread with keen interest, until very recently when I learned about the imminent release of an SDK for the Mini 3, whose optional Plus Battery makes possible 45 minutes of flight time. The Mini 3 and Mini 3 Pro are designed around those optional Plus Batteries, with motors and electronics rated to withstand the thermal stresses of up to 50 minutes of continuous operation. This overengineered ruggedness is what makes the Mini 3 an ideal drone for the long-range drone operator.

I was so excited to read about the Mini 3 Plus Battery that I ordered a Mini 3 even before learning whether or not the soon-to-be-released Mini 3 SDK would enable Litchi waypoint flights to range out further than the RC controller's signal reach. If beyond RC range flights are NOT possible with the new Mini 3 SDK, I will have absolutely no use for it even with that super long flight time.

If on the other hand, the new Mini 3 SDK does enable beyond RC Litchi waypoint flights to be launched, the Mini 3 will become the Holy Grail of long-range drone pilots the world over, literally overnight.