Battery mod thread

[WithTheBirds]

Dropping below 3.0V on any cell in the M2 forces controlled descent thr cannot be countered. That 3.0V value can be changed in parameters to as low as 2.5V, so some value below 2.5V is likely fatal.

Heads up please- where can you change the LVC to 2.5.

I don’t intend to fly down to it often but having it as an option could be nice

 

[mavicn00b]

Your concern re number of motors is largely irrelevant. Each motor has a seperate speed controller so for the purpose of establishing Vmin it is the same whether 1 motor or any number.

If the Aircraft cannot sustain lift @ 5v then its highly relevant. I suppose some experimentation in a low hover to find out at what point this occurs.

 

[mavicn00b]

Heads up please- where can you change the LVC to 2.5.

I don’t intend to fly down to it often but having it as an option could be nice

NOrmally the parameter mods are done under an older version of DJI Assistant which allowed parameter mods. This functionality was bought over to NLD however unsure if its supported by either as its a new drone/platform so it might not "see" the drone.

 

[GadgetGuy]

Heads up please- where can you change the LVC to 2.5.

I don’t intend to fly down to it often but having it as an option could be nice

I was told by @brett8883 that he had experimented with the parameter that controlled it on the M2, and the lowest acceptable value was 2.5V. I'm sure he can help us with the name of the parameter, if he reads this. I could probably benefit from changing it myself, having lost one M2P to the 3.0V setting, and barely saving another, while flying back into a headwind!

 

[WithTheBirds]

I was told by @brett8883 that he had experimented with the parameter that controlled it on the M2, and the lowest acceptable value was 2.5V. I'm sure he can help us with the name of the parameter, if he reads this. I could probably benefit from changing it myself, having lost one M2P to the 3.0V setting, and barely saving another, while flying back into a headwind!

Thanks. If can be altered I’m up for it- consider it a reserve tank. My preference would be to get home with a fragged battery rather than loose the Mavic.

 

[WithTheBirds]

If the Aircraft cannot sustain lift @ 5v then its highly relevant. I suppose some experimentation in a low hover to find out at what point this occurs.

Agreed the voltage is relavent and important- obviously. To the extent 1 or 1+n motors is employed to create the required thrust isn’t.

 

[brett8883]

Heads up please- where can you change the LVC to 2.5.

I don’t intend to fly down to it often but having it as an option could be nice

I don’t have an M2 so I’ve never done any modding on the M2 personally but most of the parameters are the same even though some are locked out on the M2. On the M1 the parameter you seek is

g_config_bat_config_emergency_voltage

That’s the last line of defense auto-landing but there are other low landing thresholds you would have to disable. Probably the easiest way to do that would be to switch to non DJI battery mode.

Again all this knowledge comes from the M1, however, most of it does translate to the M2 as long as it’s not one DJI locked out (very possible.)

 

[GadgetGuy]

Thanks. If can be altered I’m up for it- consider it a reserve tank. My preference would be to get home with a fragged battery rather than loose the Mavic.

Absolutely! Battery is $139. M2P Is $1750! Keep it in the air until the battery is completely exhausted!

 

[Justinswidebody]

None of this matters because we can't access parameters of the mavic mini :-(...

 

[MAvic_South_Oz]

With 100g more load is MM switching to S mode right away, can you post log from that flight?

I noticed by adding just 42g battery drain was almost double, and MM switched to S mode just to hover in 0 wind conditions.

And the other way too.
The Japanese mini has the 1100mAh battery, less than half the capacity or the 'rest of world' battery, and it's flight time is advertised as 18 mins, vs 30 mins, so only a little under 1/3 less.
The weight is a killer on the MM, but will be good to see how the mods here go.

 

[DanMan32]

Absolutely! Battery is $139. M2P Is $1750! Keep it in the air until the battery is completely exhausted!

Where can you get a battery for $139?

 

[Justinswidebody]

And the other way too.
The Japanese mini has the 1100mAh battery, less than half the capacity or the 'rest of world' battery, and it's flight time is advertised as 18 mins, vs 30 mins, so only a little under 1/3 less.
The weight is a killer on the MM, but will be good to see how the mods here go.

This makes sense why they have the settings to 4.2v to 3.0v.. the 1100mah battery is a lipo instead of liion... So therefore they can use all the same firmware

 

[GadgetGuy]

Where can you get a battery for $139?

Adorama.com

 

[Pilot Mike]

I read that the Mavic battery has 2 18650s inside. Here in Australia replacement batteries are 100 bucks. I have heaps of 18650s for my vape. I was wondering if anyone has tried opening the battery and using consumer 18650s in it? Would save me $$$ if this were possible

 

[Justinswidebody]

There's a claim of someone able to get a 1 hour hover time on Facebook... Looks like he made his own bcm and all

 

[Wormwood]

After looking at the flight pack, the controller circuitry & the required connections, there's some options with this right now.

It might be easier to make a housing that stay inside the mini & provides the conacts for the bottom of the cells. This allows you to place 2 individual cells (High current drain 18650's) left side has - facing out & right side cell has + facing out. with the cells in place the circuit board with interface connector is placed over & locks in with the original mechanism.

I haven't had any issues disconnecting the circuitry & reconnecting it... so I assume it can be reconnected indefinitely. There's several spring contacts sub assy. For the temp probe & the + lead for balancing the 1st cell, which are the only additional pieces you'll need, I'd expect it to be a wash in added weight since you'd lose the flight pack housing converting this.

the joy about this is that you could use any & all 18650's that are on the market or introduced in the future. Currently Samsung 2500mah INR come factory but LG offers a 3000mah high current drain cell that is more expensive but would easily get your flight times 35-40minutes. I found a 3500mah that can handle 18amp draw but you really need 20amp continuous for this to work else you risk smoking the bird in flight.

anyone have insight on higher mah 18650's that are high current draw available Now or coming soon?

Wormwood

 

[mavicn00b]

I read that the Mavic battery has 2 18650s inside. Here in Australia replacement batteries are 100 bucks. I have heaps of 18650s for my vape. I was wondering if anyone has tried opening the battery and using consumer 18650s in it? Would save me $$$ if this were possible

They're $69 here in Australia direct from DJI. Where did you see $100?

 

[Wilbur]

I see a lot of potential here. I also see potential for an after market 4k camera too.

 

[Dicky4480]

Looks good.

View attachment 85977

These arnt your pictures are they! Why are you claiming them to be yours?

 

[BJR981S]

Interesting, it seems dji only charges their batteries to 4v per cell equalling 8volts and only discharges it to 3.5volts per cell equalling 7volts.

These batteries can be charged to 4.2volts per cell and discharged to 2.5volts per cell. I wonder why they're being so conservative....

These are Lion batteries. Not LiPo batteries. They have different chemistries and different voltage ranges. The big advantage to using Lion is that they can be stored on full charge indefinately and can be discharged to 0 without significant damage unlike LiPos. Their only downside is that they cannot supply the same high current that a LiPo can. But in the case of this lightweight drone, current supply is not a big issue.