Mavic2 Battery Mods

[SkyNinja]

Hi guys it’s great to see all the battery mod for the mav 2! Here’s my set up with x2 4000mah multistar battery’s and a battery holder, looking at shedding some weight as total weight 1610, thinking of sprinting the battery’s and holding them together with electrical tape? Good-bad? Any ideas would be great!

Yes, I would definitely scrap the battery holder. I believe most people here use 3M locking Velcro two securely hold the batteries on each side. I personally use a rubber bracelet to whole my batteries underneath the bird.

 

[Dicky4480]

Yes, I would definitely scrap the battery holder. I believe most people here use 3M locking Velcro two securely hold the batteries on each side. I personally use a rubber bracelet to whole my batteries underneath the bird.

I’ve tried the locking Velcro but can’t get the battery’s seated in the position I’d like. I’ll have a look at going from underneath without the battery holder

 

[beanbubba]

Hi guys it’s great to see all the battery mod for the mav 2! Here’s my set up with x2 4000mah multistar battery’s and a battery holder, looking at shedding some weight as total weight 1610, thinking of sprinting the battery’s and holding them together with electrical tape? Good-bad? Any ideas would be great!

Have not seen a hard limit other than the bird won’t take off at all around 1900 grams. But so far it appears that 1600 grams is most likely the max efficient weight for the M2. But we still need to test over this until failure to make sure before making any declarations of the max weight.

 

[mlash]

Strip them and shorten leads and then use lighter shrink wrap!
Something like this maybe:
1M long Flat width 103mm,Diameter 65mm PVC HEAT SHRINK TUBING TUBE for18650 A015 | eBay

 

[wasp]

Alright guys! I got a mavic 2 and im looking to do some sport mods to increase agility of the drone. However im not really finding any info. I see that you are changing some parameters in the drone. How and where do you do that? Id love to get some better descent and ascending speed

I figured it out, you change the settings in DJI assistant v 1.12 in the developer mode (google it). After that you go into the parameters and just search for "sport" for those values and "max" to find the max battery discharge.

I changed some things in the sport-mode: Angle of flight to 47 degrees, Ascent speed to 9m/s and descent speed to 8m/s. Also battery-max value from 400 to 550.(is that in watts?)


I will happily help any of you if needed.

 

[714Aberdeen]

Double Battery For Mavic 2
Just Received
I tried hovering for about 27 minutes and I still have 40% left on the battery

 

[lolo780]

Double Battery For Mavic 2
Just Received
I tried hovering for about 27 minutes and I still have 40% left on the battery

Great news! Could you try a flight test vs stock?

 

[714Aberdeen]

Great news! Could you try a flight test vs stock?

Sure I will try this week I just received the battery yesterday so I cannot use the battery for just once to know the flight time , maybe I will damage the battery

 

[714Aberdeen]

This is the link
御2mavic2 改雙電池續航延時拉鋸38公裏防炸機雞
You will face a problem with the shipping of the battery because there is no carriers that will ship it to you from china

 

[beanbubba]

Got this pair insulated and ready for trials. They are heavy and might not make the cut...

 

[beanbubba]

I am wanting to do these 2 5200's plus 1 extricated factory cell. This comes in at AUW ~1800 grams. I will need to lighten the bird up. I seriously doubt the M2 can sustain flight over 1700 grams but that is yet to be proven or not.

 

[beanbubba]

Here is the AUW without any weight reduction methods on the M2 bird at all:

 

[beanbubba]

I wanted to see the far weight limit, so I added a Sunhans amp to the bird. AUW came in at 1839 grams. In past tests, I could not get an M2 to take off at all @ 1900 grams.

This config has 14,250 mAh.

You have to full up-stick to get her off the ground and immediately start forward flight. If you stop forward flight for just a few seconds, heavy auto land kicks in. Good news is that you can cancel the auto land and continue forward flight (I had to several times on this short test flight). Just the sound taking off lets you know this is at the far end of the M2's payload mass abilities. Received a lot of max motor speed reached (mostly flying into the 15 mph winds). Other than that, she flew and no noticeable issues otherwise. You can see in the airdata link that there were several "not enough ESC force" listed, but that is normal from what we have seen before.

After landing the rear motors were hot to the touch, but nothing near the high temps we saw on the M1. I am speculating that I think you could attempt a long flight in this configuration, but it will have to be tested to be proven in an actual flight. Gut instinct from past super heavy load testing, you should use some method to lock the front arms in place at this mass. It flies like an oil tanker and any sport mode maneuvers might fold back the front arms mid-flight.

Anyway, this is just a solid verified data point of the upper end of M2 weight/mass abilities as you plan your future heavy load missions.

 

[lolo780]

If you're seeing max motor speed then you need to add some prop to get rpms down.

Motor simulator example. I used this a lot when picking ebike motors. Electric motor power drops off sharply as the no load speed is reached. On a boat/aircraft this would be under propped.

Motor Simulator - Tools

APC has some great prop data and by looking at the numbers you can see trends for pitch/diameter vs airspeed vs efficiency.

Performance Data | APC Propellers

For motor temps, raising the motors off the arm will help, as well as removing the lower covers. I haven't measured the motor leads on the M2 but there might be some gains changing to a thicker gauge wire.

 

[beanbubba]

If you're seeing max motor speed then you need to add some prop to get rpms down.

Motor simulator example. I used this a lot when picking ebike motors. Electric motor power drops off sharply as the no load speed is reached. On a boat/aircraft this would be under propped.

Motor Simulator - Tools

APC has some great prop data and by looking at the numbers you can see trends for pitch/diameter vs airspeed vs efficiency.

Performance Data | APC Propellers

For motor temps, raising the motors off the arm will help, as well as removing the lower covers. I haven't measured the motor leads on the M2 but there might be some gains changing to a thicker gauge wire.

I am not nearly as versed as you on this topic. Can you recommend a prop to test next for this configuration if you were doing for your own tests?

Again, I am only a hobbyist and not an electrical engineer. Could thicker wire potentially reduce motor temps?

 

[lolo780]

I am not nearly as versed as you on this topic. Can you recommend a prop to test next for this configuration if you were doing for your own tests?

Again, I am only a hobbyist and not an electrical engineer. Could thicker wire potentially reduce motor temps?

For prop testing first you need RPM. The Mavic RC averages all 4 rpms which is probably ok, but ideal is an optical tach. (Or
DAT files that can be read)

RCD3063 Magic Mirror Helicopter Optical Tachometer V2

PMW avg % can be read off the RC, but again just an average of all 4 motors.

Because of the dihedral angle, the rear props will be tilted more into the airflow so will see a higher air speed compared to the fronts. I would start at the back and go higher pitch. Stock bodywork limits the diameter to about 8.5" but you can always trim a 9" prop down to 8.7 or so.

Reducing voltage drop will reduce current for a given power output, and heat is a function of current squared. On the same line of thinking, if 5s could work on the M2 you could make more power with the same or less current.

 

[beanbubba]

For prop testing first you need RPM. The Mavic RC averages all 4 rpms which is probably ok, but ideal is an optical tach. (Or
DAT files that can be read)

RCD3063 Magic Mirror Helicopter Optical Tachometer V2

PMW avg % can be read off the RC, but again just an average of all 4 motors.

Because of the dihedral angle, the rear props will be tilted more into the airflow so will see a higher air speed compared to the fronts. I would start at the back and go higher pitch. Stock bodywork limits the diameter to about 8.5" but you can always trim a 9" prop down to 8.7 or so.

Reducing voltage drop will reduce current for a given power output, and heat is a function of current squared. On the same line of thinking, if 5s could work on the M2 you could make more power with the same or less current.

You know I am going to buy one of these, is this the model I should get??

And don't forget the wire gauge question.

As always, thanks Lolo.

 

[lolo780]

Forgot about the props.

I would try this one trimmed to fit.
APC 9x4.5MR

This might not be enough but only one way to find out. Nice thing is APC are dirt cheap.
APC 8x4.5 Multirotor Propeller | Innov8tive Designs

Since we're not interested in hovering, prop performance at 30-35mph is most important.

Phantom 4 quick release adapters can fit the M1 which means they should fit the M2 and would allow 9450 and V2 9455 props to be tested with trimming.

 

[lolo780]

You know I am going to buy one of these, is this the model I should get??

And don't forget the wire gauge question.

As always, thanks Lolo.

I just picked that as an example. Any tach that can read 10k rpm will work fine. Also heli tachs can typically measure 4 or 5 blade rotors so can be divided down on our 2 blade props. May as well buy a good one though.

Calculate voltage loss by estimating motor current and plug into an online calculator.
For example:


0.43% improvement in this example. Numbers are just a guess, measuring is required. Probably on the conservative side for a rear motor. Calculate your total watt hours used on a heavy flight and use say 30% for a single rear motor power.

 

[beanbubba]

I just picked that as an example. Any tach that can read 10k rpm will work fine. Also heli tachs can typically measure 4 or 5 blade rotors so can be divided down on our 2 blade props. May as well buy a good one though.

Calculate voltage loss by estimating motor current and plug into an online calculator.
For example:
View attachment 57003View attachment 57004

0.43% improvement in this example. Numbers are just a guess, measuring is required. Probably on the conservative side for a rear motor. Calculate your total watt hours used on a heavy flight and use say 30% for a single rear motor power.

OK, can you have too much wire? What would be your best guess at the max gauge to use?