Building an off-the-grid solar charger for my mavic 2 pro. Please correct me if I'm wrong, I'm fairly uncomfident with electricity.

[krikite]

Hello guys,

So here's the thing, I currently am heading for a 10 days hike. One of the most beautiful in the world (so they say) in the peruvian Andes and I definitely want to be able to film that.

So, I want to be able to charge my mavic batteries on the go with the help of the Sun.

So, if I am correct the maximum charging voltage of a battery is 17.4 volts.

Hence, I need a solar panel delivering around 20 volts and then reduce the voltage with a regulator such a this one :

I'll have to weld a cable going from the solar panel to this little device and then charge my external battery. Because from what I understand from this blog, the Mavic batteries can't be charged by an unstable source such as a solar charger. Therefore, it is necessary to charge first an external battery and then the batteries.

Am I right until now ? So simply weld the regulator to a cable going out of the solar charger, then simply charge my battery with some kind of adaptater. Fly during the day, charge during the night and repeat ?

Data wise, I do not want to change my external battery. So am I correct if I assume according to my battery specs I linked earlier "To recharge this power bank, there’s a DC input port that you have to use an AC adapter with and the recharge rate of the power bank is 19V/1.6A" I need to set the regulator on 19V ?

What about the amperage ? I need to be sure the solar panel has more than 1.6A, right ?

Then what about loss of energy ?

What do you think guys ? Am I right on this ? I am traveling and will only have one shot since it's so expensive shipping anything from the US and I want to be sure I am pretty right about the whole thing.

 

[krikite]

It also seems the original mavic charger might be a source of problems. I will probably get a cheap chinese one to avoid any restriction imposed by DJI inside the charger.

 

[MAvic_South_Oz]

Yes, you need to charge a battery or batteries in parallel, 12v normally, usuing a good quality solar controller of capacity to handle the solar panels used.
You can use an inverter off the batteries for mains power.

What I'd do is charge the battery(ies) and run the DJI 12v charger off one of these.
The 12v charger is much faster than the mains one, and you can still use the DJI multi charger to charge multiple batteries in turn.
You might need a step converter, as the DJI charger requires 13.1v, see here . . . Fly-more kit car charger for Iceland

 

[Neil Reid]

Hello guys,

So here's the thing, I currently am heading for a 10 days hike. One of the most beautiful in the world (so they say) in the peruvian Andes and I definitely want to be able to film that.

So, I want to be able to charge my mavic batteries on the go with the help of the Sun.

So, if I am correct the maximum charging voltage of a battery is 17.4 volts.

Hence, I need a solar panel delivering around 20 volts and then reduce the voltage with a regulator such a this one :

I'll have to weld a cable going from the solar panel to this little device and then charge my external battery. Because from what I understand from this blog, the Mavic batteries can't be charged by an unstable source such as a solar charger. Therefore, it is necessary to charge first an external battery and then the batteries.

Am I right until now ? So simply weld the regulator to a cable going out of the solar charger, then simply charge my battery with some kind of adapter. Fly during the day, charge during the night and repeat ?

Data wise, I do not want to change my external battery. So am I correct if I assume according to my battery specs I linked earlier "To recharge this power bank, there’s a DC input port that you have to use an AC adapter with and the recharge rate of the power bank is 19V/1.6A" I need to set the regulator on 19V ?

What about the amperage ? I need to be sure the solar panel has more than 1.6A, right ?

Then what about loss of energy ?

What do you think guys ? Am I right on this ? I am traveling and will only have one shot since it's so expensive shipping anything from the US and I want to be sure I am pretty right about the whole thing.

Good plan. I've been in the solar business; some thoughts for you;

- DC power (such as from solar) is very stable and quiet. Putting a regulator with simple tuning (like the one you're considering will ensure the power stays within parameters

- solar works great from about 10:00AM to 2:00PM unless you have a tracking mechanism (heavy, large, awkward shape. Or you can adjust your panel to face the sun but before 10AM and 2PM, the amount of energy provided is about half of the peak production window. Frankly, I just point it to where the sun is at 12 noon and leave it at that.

- what are you considering for a panel? You'll probably want something flexible, or that folds into smaller pieces. See next.

- the top layer of the panel is glass and brittle. The silicon elements and ribbon cable connections don't like vibration or mechanical shock (like dropping). How you store the panel for air travel, automobile and foot travel will be important.

- any shade covering the panel will significantly reduce the productivity- up to half pretty quickly.

- lots of good solar manufacturers but I'd recommend Renogy- good products, developed by credentialed electrical and mechanical engineers. Good support.

- why would you weld a connector to anything non-pressurized? Simply get good connectors or even better yet mil-spec connectors.

- run your system five or ten times before you pack and head off. You'll be surprised at how many little details there are in a system like this- you'll want to resolve those issues before you head out.

Hope this helps; there's more to this, but this will get you well into the project.

Good luck!

 

[brett8883]

Personally, I’d take 3 or so batteries and fly sparingly each day- concentrating on the best stuff. Think of it as fluff compared to the shots you will take at ground level. If you are backpacking, a suitable sized solar panel, 2nd charging battery and related parts including the drone and it’s parts will weigh a lot. Also, those 3.3Ah drone batteries will need 2-1/2 hours to charge from empty with a 1.5 Amp solar panel (3.3Ah/1.5Ah - meaning the battery bank will need at least that to keep up with your 1.5 Ah panel).

Sounds like a great trip though, when are you going?

I agree with @AMann. Maybe you are a world class hiker and don’t need me to tell you this but when I’ve been on long hikes like this you and you will be cursing yourself for bringing all this weight. Hopefully you have a pack mule or a Sherpa.

Hello guys,

So here's the thing, I currently am heading for a 10 days hike. One of the most beautiful in the world (so they say) in the peruvian Andes and I definitely want to be able to film that.

So, I want to be able to charge my mavic batteries on the go with the help of the Sun.

So, if I am correct the maximum charging voltage of a battery is 17.4 volts.

Hence, I need a solar panel delivering around 20 volts and then reduce the voltage with a regulator such a this one :

I'll have to weld a cable going from the solar panel to this little device and then charge my external battery. Because from what I understand from this blog, the Mavic batteries can't be charged by an unstable source such as a solar charger. Therefore, it is necessary to charge first an external battery and then the batteries.

Am I right until now ? So simply weld the regulator to a cable going out of the solar charger, then simply charge my battery with some kind of adaptater. Fly during the day, charge during the night and repeat ?

Data wise, I do not want to change my external battery. So am I correct if I assume according to my battery specs I linked earlier "To recharge this power bank, there’s a DC input port that you have to use an AC adapter with and the recharge rate of the power bank is 19V/1.6A" I need to set the regulator on 19V ?

What about the amperage ? I need to be sure the solar panel has more than 1.6A, right ?

Then what about loss of energy ?

What do you think guys ? Am I right on this ? I am traveling and will only have one shot since it's so expensive shipping anything from the US and I want to be sure I am pretty right about the whole thing.

I’m interested to see the 20 volt 1.6 amp solar panel you think you be able to carry for 10 days through the Andes ?. Sorry I couldn’t resist.

I think you may need to check with somebody who’s done this before to get a real idea what you are getting into. The Andes are no joke and if you are really going with no power no vehicles unless you have a bunch of pack miles and a staff to lug your stuff around you will DIE trying to carry all that stuff around.

 

[Thomas B]

Maybe pack the gear on a llama?

 

[brett8883]

Maybe pack the gear on a llama?

Maybe 2 or three

 

[MAvic_South_Oz]

Sorry ! I missed the 10 day hike thing, just saw off grid.

I'd take 3 or 4 (up to 6?) batteries and just fly selectively . . . plan each flight so you can get as close as possible to the scene, take off, get the shot / video as quickly as possible, get down and save battery for another flight.

When batteries get to say 20%, save those for straight up, take pic / vid, down again.
Just simple straight down work, no flying away from take off point.

 

[AMann]

I was trying to edit my earlier reply and deleted it! ? Anyway, as brett mentions, you will need a 30watt solar panel (watts= amps x volts). A 20v 30watt panel is rather large. For example, look at how big this 30w 12v panel is- it’s 21” x 18” and weighs 6 lbs:

Goal Zero Boulder 30 Solar Panel Amazon.com : Goal Zero Boulder 30 Solar Panel : Garden & Outdoor

 

[krikite]

Guys just to give you an idea Mavic pro batteries cost half of a peruvian salary, actually probably more around 70% after importation taxes. I am not going to spend thousand of dollars just for some drone batteries.

I must precise I have a very low budget. There is no way I'm spending 800 dollars in Mavic Batteries (which is not even a solution considering their weight and the fact that after 3 days I'll end up with nothing but bulky useless and fragile electronic gear) neither will I ship myself a very high end solar charger with a sun detection system that follows the light or something. I would love building me a super good set up, but right now I am im the middle of Peru and my means are extremely limited so I want a solution that can give me the possibility of charging the batteries during a trekk even if it's slow (even one batterie in 12 hours is fine).

Amazon.com: Voltaic Systems Arc 20 Watt Solar Laptop Charger | 2 Year Warranty: Home Audio & Theater

Buy Voltaic Systems Arc 20 Watt Solar Laptop Charger | 2 Year Warranty: Chargers & Adapters - Amazon.com ✓ FREE SHIPPING for eligible purchases

www.amazon.com

1.7 lbs. I don't really see why I need a lama to carry 1.7 lbs. Yes yes the Mavic has its own weight but come on, it's not like it's undoable. When reading the messages it sounds like I'm trying to carry gym equipment to workout in the mountain or something. I just need to buy a lighter and more compact sleeping bag and yoohoo it's the same weight again.

Look at this guy over there he's using this same panel :

He seem to be doing fine with minimal weight and a 20W solar panel.

I might be totaly wrong guys, I definitely take your advices into consideration. But keep in mind I am looking for a very low cost and low to medium efficiency way to charge my batteries. I just want to walk during the day with a solar panel strapped on my backpack. Or strapped at the tent. I just want to understand how to do this considering the electricity restrictions and necessities of the batteries. As I said, even if I can only get one battery per day it's enough even if the more the better obviously.

I'll read the technical advices more deeply tomorrow and answer to questions at the same time, thanks already for the interest !

 

[AMann]

Guys Mavic pro batteries cost half of a peruvian salary, I am not going to spend thousand of dollars just for some drone batteries. I'll read the rest tomorrow morning, thanks for the heads up !

Amazon.com: Voltaic Systems Arc 20 Watt Solar Laptop Charger | 2 Year Warranty: Home Audio & Theater

Buy Voltaic Systems Arc 20 Watt Solar Laptop Charger | 2 Year Warranty: Chargers & Adapters - Amazon.com ✓ FREE SHIPPING for eligible purchases

www.amazon.com

1.7 lbs. I don't really see why I need a lama to carry 1.7 lbs. Yes yes the Mavic has its own weight but come on, it's not like it's undoable. When reading the messages it sounds like I'm trying to carry gym equipment to workout in the mountain or something.

Oh man, that Amazon add is mislabeled- look at the fine print on the photos of the back of the solar panel:



I think it says Output: 12v 1,200 mA (1.2amps) and USB: 5v 2.0 amps. That means its only putting out 10watts. Not sufficient for powering your batteries with just the solar panel by itself. Hou will also need the Voltaic 24amp lithium with this setup as well:

Voltaic Systems Arc 20 Watt Rapid Solar Laptop Charger, 24,000mAh | Includes a Battery Pack (Power Bank) and 2 Year Warranty | Powers Laptops Including MacBook https://www.amazon.com/dp/B002W9ICWA/ref=cm_sw_r_cp_api_i_4PUKDb2KC7Y5M

So with the 24 amp lithium battery alone, you can probably charge a 3.4 amp Mavic battery up to 5 times if it does output 18v V(heat and resistance eats up the remainder of the power), but if its less and he’s using a step up transformer to get 18v, it wont be able to keep up, definitely over 10 days if you aren't solar charging it for at least 3+ hours per day per battery.

 

[krikite]

Man. Please read my original message I tried to include all the details in order to receive the most precise advices possible.

I mentionned already that a guy on a blog discovered that it was not possible to power the batteries from a solar charger due to the unconsistency of the electricity source (being solar) because of the way the Mavic batteries are made.

Therefore there has to be an intermediate, an external powerbank from which you charge the drone batteries afterwards.

Hence the solar charger does not need to match the requirements of the Mavic Batteries.

It is definitely possible however that this solar charger isn't the most efficient one for what I am looking for or that it will not be useful in any way to charge my Powerbank (I linked the specs of it in the original message as well). It simply is an example of a lightweight solar charger that the swedish guy in the video seem to be using with success.

As I said, I will have more technical looks tomorrow, I just wanted to clarify what I was looking for (it was pretty unclear I gotta admit, budget wise etc...)

I'm off, good night fellow pilots (and good day for some others !) !

EDIT :
Voltaic Systems Arc 20 Watt Rapid Solar Laptop Charger, 24,000mAh | Includes a Battery Pack (Power Bank) and 2 Year Warranty | Powers Laptops Including MacBook https://www.amazon.com/dp/B002W9ICWA/ref=cm_sw_r_cp_api_i_4PUKDb2KC7Y5M


This is the best and easiest solution by very far. It is however way out of my budget. I do not want to get rid of my powerbank. Hence my desire to build the voltage regulator system myself. I'd just like to get a solar charger and regulate the voltage to be able to charge my powerbank and then charge my Mavic. Which is basically the same as this kit since the voltage regulator is included in the powerbanks directly. What an awesome system by the way, I wish I had the money ! Later for sure !

 

[AMann]

I read your post, but your original reference showed only a solar panel. Using a seperate power cell is a very good idea, but keep in mind- with that battery bank you speak of, or even the 24amp voltaic battery and the solar panel in the advert, you will still need at least 3 hours of solid solar charging per day per battery to keep it up.

Just to see what it takes to keep a Mavic flying, here’s an example: I just made this similar setup for $150 - it’s a 35amp 12v solar charged Jell Cell that will also output 18v. It’s way too heavy for hiking, but a llama could handle it.

Theoretically, it should be able to charge a Mavic battery up to 10 times, but again, heat and resistance for the 18v step up transformer will take its toll and I wont get that many recharges. So, it is recharged by a 50watt solar panel and can also recharge off my truck as well. Even with a 50watt solar panel (4.2 amps), it would take over an hour to charge a single Mavic Battery, or to refresh this battery after using it to recharge a Mavic cell.

 

[MAvic_South_Oz]

There is no way I'm spending 800 dollars in Mavic Batteries (which is not even a solution considering their weight

I understand regarding the cost for you.
However that aside, the weight alone of a charging system to keep flying at any reasonable level is going to be a lot heavier than some drone batteries.
The limited solar charging capabilities of something you can carry, limited time of charging light and sun orientation, canopy cover from vegetation, you'd be lucky to charge a battery in a couple of days.

I bushwalk long distances / periods and would never consider taking my drone(s), even the Spark.

If you are keen on that fellows setup, try it at home for a few days hiking around near home to test it before lugging it on a 10 day walk.

How many batteries do you have ?
You must have at least two I guess, one to use and one to be charging, or do you plan to just do one flight a day and charge the drone battery at night ?

 

[krikite]

If you are keen on that fellows setup, try it at home for a few days hiking around near home to test it before lugging it on a 10 day walk.

I'll follow that advice. I was actually planning to do shorter 3 days hikes before going for the 10 days one in any case. But if I feel comfortable during that "little trekk" and feel able to take the drone into the 10 days one, then hell yeah I'll take it.

So with the 24 amp lithium battery alone, you can probably charge a 3.4 amp Mavic battery up to 5 times if it does output 18v V(heat and resistance eats up the remainder of the power), but if its less and he’s using a step up transformer to get 18v, it wont be able to keep up, definitely over 10 days if you aren't solar charging it for at least 3+ hours per day per battery.

So, you're saying with such a battery I could theorically have 5 mavic charges already. How did you arrive to such conclusion ? (sincere question) What does mean a "step up transformer" ?

Good plan. I've been in the solar business; some thoughts for you;

- DC power (such as from solar) is very stable and quiet. Putting a regulator with simple tuning (like the one you're considering will ensure the power stays within parameters

- solar works great from about 10:00AM to 2:00PM unless you have a tracking mechanism (heavy, large, awkward shape. Or you can adjust your panel to face the sun but before 10AM and 2PM, the amount of energy provided is about half of the peak production window. Frankly, I just point it to where the sun is at 12 noon and leave it at that.

- what are you considering for a panel? You'll probably want something flexible, or that folds into smaller pieces. See next.

- the top layer of the panel is glass and brittle. The silicon elements and ribbon cable connections don't like vibration or mechanical shock (like dropping). How you store the panel for air travel, automobile and foot travel will be important.

- any shade covering the panel will significantly reduce the productivity- up to half pretty quickly.

- lots of good solar manufacturers but I'd recommend Renogy- good products, developed by credentialed electrical and mechanical engineers. Good support.

- why would you weld a connector to anything non-pressurized? Simply get good connectors or even better yet mil-spec connectors.

- run your system five or ten times before you pack and head off. You'll be surprised at how many little details there are in a system like this- you'll want to resolve those issues before you head out.

Hope this helps; there's more to this, but this will get you well into the project.

Good luck!

Hey man ! I'm wondering : what do you mean by anything non-pressurized ? Could you please clarify that line, I am very newbie and am not sure to understand.

I will definitely want something want something that is foldable such as that one maybe

However that aside, the weight alone of a charging system to keep flying at any reasonable level is going to be a lot heavier than some drone batteries.

But why ? I just need a solar charger. Some of them weight very little.

I am just not sure to understand so please guys correct me if I'm wrong :

1. Buy a solar charger that is able to charge this Power bank. With my very little understanding of Electricity I am not sure that this panel (for instance) would be sufficient. Correct me if it would not be sufficient.
2. Buy a voltage regulator such as this one
3. Weld the regulator to a cable going out of the solar charger.
4. Set it up to the voltage requiered to charge the Power bank.
5. Then do I need to plug use the original charger of my Power bank ? Meaning do I need to use the big block ? Or I can just put the cable directly into the battery because of the voltage regulator previously installed. This part is a bit blurry for me I am not sure to understand weither I need to use the full charger or not. (the cable with the original big block attached to it). Please tell me the english name of this big block.
6. Charge my Power bank with the solar charger strapped to my back.
7. Fly during the day with the Mavic Batteries
8. Charge the Mavic batteries at night with the Power bank
9. Repeat

So if I understand, you guys are saying it could work but would be very very slow ?

If it can charge at least 60% of a battery each day, I'll be super fine. I mean... 2kg of gear for some insane Hasselblad drone footage... I'm willing to sweat for that. What do you think ?



EDIT : The trekk is the Huayhuash Circuit.

 

[AMann]

So, you're saying with such a battery I could theorically have 5 mavic charges already. How did you arrive to such conclusion ? (sincere question) What does mean a "step up transformer" ?




Hey man ! I'm wondering : what do you mean by anything non-pressurized ? Could you please clarify that line, I am very newbie and am not sure to understand.

I will definitely want something want something that is foldable such as that one maybe



But why ? I just need a solar charger. Some of them weight very little.

I am just not sure to understand so please guys correct me if I'm wrong :

1. Buy a solar charger that is able to charge this Power bank. With my very little understanding of Electricity I am not sure that this panel (for instance) would be sufficient. Correct me if it would not be sufficient.
2. Buy a voltage regulator such as this one
3. Weld the regulator to a cable going out of the solar charger.
4. Set it up to the voltage requiered to charge the Power bank.
5. Then do I need to plug use the original charger of my Power bank ? Meaning do I need to use the big block ? Or I can just put the cable directly into the battery because of the voltage regulator previously installed. This part is a bit blurry for me I am not sure to understand weither I need to use the full charger or not. (the cable with the original big block attached to it). Please tell me the english name of this big block.
6. Charge my Power bank with the solar charger strapped to my back.
7. Fly during the day with the Mavic Batteries
8. Charge the Mavic batteries at night with the Power bank
9. Repeat

So if I understand, you guys are saying it could work but would be very very slow ?

If it can charge at least 60% of a battery each day, I'll be super fine. What do you think ?

Assuming its the same voltage:
Battery capacity (Ah) / load amps (Mavic Battery amps @3.4) = number of recharges. Then subtract 10% or more for inefficiency like battery heat, wire resistance, etc.

A step up transformer increases the voltage like the one you posted. They draw amps from the battery too, and wasted heat as well so you have to add that into the equation as well.

I use the same one that increases voltage from 12v to 18v, but cant get to it right now to give an example of how many amps it uses to convert the voltage- will post it later today.

 

[krikite]

I read your post, but your original reference showed only a solar panel. Using a seperate power cell is a very good idea, but keep in mind- with that battery bank you speak of, or even the 24amp voltaic battery and the solar panel in the advert, you will still need at least 3 hours of solid solar charging per day per battery to keep it up.

Just to see what it takes to keep a Mavic flying, here’s an example: I just made this similar setup for $150 - it’s a 35amp 12v solar charged Jell Cell that will also output 18v. It’s way too heavy for hiking, but a llama could handle it.

Theoretically, it should be able to charge a Mavic battery up to 10 times, but again, heat and resistance for the 18v step up transformer will take its toll and I wont get that many recharges. So, it is recharged by a 50watt solar panel and can also recharge off my truck as well. Even with a 50watt solar panel (4.2 amps), it would take over an hour to charge a single Mavic Battery, or to refresh this battery after using it to recharge a Mavic cell.

View attachment 82755
View attachment 82756

Very nice looking set up. I'd definitely like to have something similar when I get back home in civilization hahaha

Using a seperate power cell is a very good idea, but keep in mind- with that battery bank you speak of, or even the 24amp voltaic battery and the solar panel in the advert, you will still need at least 3 hours of solid solar charging per day per battery to keep it up.

It does seem like a good deal to me !

Assuming its the same voltage:
Battery capacity (Ah) / load amps (Mavic Battery amps @3.4) = number of recharges. Then subtract 10% or more for inefficiency like battery heat, wire resistance, etc.

Thanks !

EDIT :

Well I guess you are right! Well it takes about 6h of good sun for my Arc 20W to charge the Voltaic Battery of 20000mAh... so I guess it would be the same for the OmniCharger if it can accept variable input power

Quote from the guy of the video I posted previously. That sounds ******* awesome to be honest !

EDIT 2 : I have this solar panel already but as I understood there will not be any use of it right ?

 

[AMann]

I'll follow that advice. I was actually planning to do shorter 3 days hikes before going for the 10 days one in any case. But if I feel comfortable during that "little trekk" and feel able to take the drone into the 10 days one, then hell yeah I'll take it.



So, you're saying with such a battery I could theorically have 5 mavic charges already. How did you arrive to such conclusion ? (sincere question) What does mean a "step up transformer" ?




Hey man ! I'm wondering : what do you mean by anything non-pressurized ? Could you please clarify that line, I am very newbie and am not sure to understand.

I will definitely want something want something that is foldable such as that one maybe



But why ? I just need a solar charger. Some of them weight very little.

I am just not sure to understand so please guys correct me if I'm wrong :

1. Buy a solar charger that is able to charge this Power bank. With my very little understanding of Electricity I am not sure that this panel (for instance) would be sufficient. Correct me if it would not be sufficient.
2. Buy a voltage regulator such as this one
3. Weld the regulator to a cable going out of the solar charger.
4. Set it up to the voltage requiered to charge the Power bank.
5. Then do I need to plug use the original charger of my Power bank ? Meaning do I need to use the big block ? Or I can just put the cable directly into the battery because of the voltage regulator previously installed. This part is a bit blurry for me I am not sure to understand weither I need to use the full charger or not. (the cable with the original big block attached to it). Please tell me the english name of this big block.
6. Charge my Power bank with the solar charger strapped to my back.
7. Fly during the day with the Mavic Batteries
8. Charge the Mavic batteries at night with the Power bank
9. Repeat

So if I understand, you guys are saying it could work but would be very very slow ?

If it can charge at least 60% of a battery each day, I'll be super fine. I mean... 2kg of gear for some insane Hasselblad drone footage... I'm willing to sweat for that. What do you think ?



EDIT : The trekk is the Huayhuash Circuit.

Keep in mind my calculation is based on recharging an empty battery- you will save time and increase the total number of recharges possible from your battery bank if you don’t drain your Mavic batteries too low. Besides, only those who tend loose their drones do that anyways!

 

[krikite]

Solar Chargers for Drones: DJI, Yuneec, Parrot, and 3DR | Voltaic Systems Blog

Discover solar chargers for drones. The Voltaic team offers tutorials on how to charge your DJI, Yuneec, Parrot, or 3DR drone from solar.

blog.voltaicsystems.com

Seriously the easiness of it makes it so tempting for the 200 dollars this system costs...
Pretty sad I won't be able to get it in Peru due to the importations taxes.

Keep in mind my calculation is based on recharging an empty battery- you will save time and increase the total number of recharges possible from your battery bank if you don’t drain your Mavic batteries too low. Besides, only those who tend loose their drones do that anyways!

No clearly I will calculate that I won't go under 20%.

 

[DanMan32]

You'll need 50W minimum to directly charge the M2 battery. I believe the DJI car charger is about 72W as it requires 6A@12v. It will work down to about 11.2v at the charger input before it cuts out, which is why it tends to not work when the car is not running. The car's internal wiring resistance creates at least a 1v drop when 6A is going through it.

So a 20W solar panel alone won't do it unless you have an auxiliary battery that you constantly charge, and charge the Mavic off of the aux battery less than half the time you're charging the aux battery.