DJI Mavic, Air and Mini Drones
Friendly, Helpful & Knowledgeable Community
Join Us Now

Hiking Mavic Pro - Battery Bank Charging System - Proven

Aerial Gopher

Well-Known Member
Joined
Feb 17, 2017
Messages
179
Reactions
130
Location
Gopher Hotel
After fighting with the mavic car charger with its odd voltage requirements, I have found a solution that works if you want a true portable solution for charging your batteries.
Good if you are in remote locations, hiking, if car 12 volt socket shuts off when ignition is off.

First this power bank does 12, 16, and 19 volt. Tested voltages are 13.3-13.6, 16.1-16.5, 20.3-20.5, with 5 amp max at 12 volt, and 3.75 amp at 16 volt, and 3 amp max at 19 volt.
The mavic charger powered up at the 12 volt setting, but drew too many amps, causing the battery bank to power off. at the 16 volt setting, it was too high and the mavic car charger did not power on. I initially tried this one battery bank with a 12 volt lead acid battery in series, and got the mavic charger to work. So I ordered the second battery bank same as the first one.

The plug I built is a bit mis leading, these battery banks are connected in series, and the connection is made inside the plug to make it look nicer.

the battery bank at the 12 volt setting outputs 13.? volts and putting them both in that setting SHOULD work, but again, the mavic charger light ( Light on the charger ) flashes, and when its flashing, its not charging, but the Mavic BATTERY lights are blinking as if charging.... wasting your time waiting. So I tried the battery banks at 16 volt setting, both of them, and the mavic charger light stayed solid green, got warm and charged the mavic battery. YAY! But How many could I charge with my set up? Well, lets just say, i didnt have enought energy to hike that much to find out.... it would of been a long day. I have 4 mavic batteries, charged them all up, and my two power banks. I also charged a small 6600mah USB only power bank to charge the controller when needed.. more later..

As i hiked, and found things to film, I did, and then landed, waited for the battery to cool while I Hiked. then I started the charging with my "farmer charger " :) I set a timer on my cell phone for 42 minutes, so I could check on the battery. CHARGED! YAY!

I initially had the battery in the backpack, but then put it in the side where there was mesh so I could quickly look at it to see its charge state. As I hiked, I had a battery chargin, NICE!

I bet you are wondering, how many times could i charge the mavic batteries..... well, lets just say, I had full batteries when I got to the trail, and when I left. The two big battery banks I used charged the Mavic batteries 7, YES SEVEN times. With my originally charged 4 full batteries, I would have 11 battery cycles! AWESEOME! Only to carry an extra about 4 lbs of battery banks.

I used another small power bank to charge the controller also while walking. But this is only becuase that controller charger my phone, which is a samsung s7 edge, and went to 75% charge level. I wish DJI would fix this so I can disbale the charging of the phone from teh Controller! The 6600 mah battery bank was only about 50% used at the end of my trip. ( after 7 drone battery flights )

Each Mavic battery was drained to 20% +- 1%, waited about 10 min for cool down, then charged while walking. Outside temp was around 3 Deg Celcius.
Battery Banks are 45000 mAh by specifications, and 160 Watt Hours by specifications. I cannot say if this is TRULY accurate, but it is close. Once you factor in heat loss, conversion from battery to 16 volts, it seems right. Even 45 watt hour mavic battery x 3.5 times charge, yes 3.5, as there was two battery banks.

The quirky thing about this set up is these few things:
- when one bank is dead, the system doesnt work.
- the power bank shuts off in 30 seconds when there is no load, SOMETIMES this shuts off when the charge of the mavic battery is done, but not all the time, so you have to keep an eye on it to shut it off manually as to not waste the power in the battery bank.
- the actual cable that plugs into the battery bank HAS to be pulled out then select the voltage then re-insert it. This is a saftey feature as to not pick the wrong voltage while a device is connected.
- the battery banks have 2 USB ports as seen in the photos, you can use one for the controller, and the other one for the cell phone. I would try to balance the use between the two battery banks so that one doesnt get depleted before the other, since they are connected in series, needs both to charge the mavic battery.
- The battery bank can be charged with DC power from 14 Volt to 20 Volt. This does not charge with car off, but does when running as alternator increases volts to 14.5 or so.
- With a notebook charger at 18 volt, 1.76 amps, takes 4 hours to charge each battery bank
- Battery bank can be charged with Micro USB, but takes long. 22 hours at USB2.0 ( think its 250 milliamp ) I preffer charging batteries slow, they will last longer.
- If you are so inclinded, you can use a 5 volt USB foldable solar panel for those longer trips and will stop somewhere to set it up to charge, or larger solar panel if you REALLY want to carry one.
- Battery bank CANNOT be charged at the same time as powering a device, as soon as input current is put in, it will power off the output ports.

After I started charging the first battery, the system was going continuously non stop charging mavic batteries. Kept the battery banks warm :) 4 mavic batteries was nice to have, after you consider cool down time 10 minutes and charging time being 45 minutes, you basically need 1 hour for the cycle. BUT you can fly two batteries in that same time. So having that " reserve " battery for when you really need a fully charged one, is nice to have.

I put small velcro on them to hold them together when in a back pack as they are aluminum, and would scratch easy.

Cost of the battery banks was $75.00 canadian, and the second one I had to buy from another supplier as the first guy ran out, but he did order more... seond one as $95 Cnd. Honestly its the best price I had seen for this size of battery bank. BEWARE of stated specs on ebay and amazon... I have seen all sorts of specs, and they cant fit a battery 50% bigger than this one in 30% less space... it just cant happen.

Yes, I know that was a Looooong Post! But its worth it, $160 Cnd for 2 battery banks to make 7 x $125 = $875.00 in battery life.... Plus a 12 volt socket I had laying around.
 

Attachments

  • 20170323_035113.jpg
    20170323_035113.jpg
    97.1 KB · Views: 598
  • 20170323_035149.jpg
    20170323_035149.jpg
    90.8 KB · Views: 557
  • 20170323_035201.jpg
    20170323_035201.jpg
    94.9 KB · Views: 562
  • 20170323_035544.jpg
    20170323_035544.jpg
    147.4 KB · Views: 576
  • 20170323_035523.jpg
    20170323_035523.jpg
    142.9 KB · Views: 587
  • 20170323_035209.jpg
    20170323_035209.jpg
    95.8 KB · Views: 558
  • 20170323_035605.jpg
    20170323_035605.jpg
    158 KB · Views: 590
  • 20170323_035621.jpg
    20170323_035621.jpg
    101.2 KB · Views: 571
  • 20170323_035645.jpg
    20170323_035645.jpg
    160.7 KB · Views: 578
This is very interesting, I was thinking of a similar situation (I have a 25AH battery bank which is configurable like this one for several DC voltages, designed for charging laptops).

When you say you hooked these up in series though... What? Seems both like a bad idea (not sure how that will affect the banks) not to mention you're essentially setting your voltage to 24v then... Is that intentional? Seems like running them in parallel would make more sense (double current carrying capacity).

I'm half-tempted to build a portable charge-bank out of a DC-DC regulator that puts out stable 13.1V (or whatever the exact charge voltage is). And has a bank of big *** batteries from hobbyking in it, going straight from the battery to a DJI charge connector (instead of going through the car charger, for more efficiency).

I know someone on here has tested it using their car with a DC-DC regulator board, and fast charged at 100W. So no reason a high C lipo wouldn't do the same, but be portable...

Anyway for now I'll be sticking to official DJI stuff, but soon the DIY spirit won't be held back and I'll start tinkering I'm sure.

Interesting experiment, thanks for sharing!

edit: One of these: Multistar High Capacity 20000mAh 4S 10C Multi-Rotor Lipo Pack

Would hold just about 300Wh, and charging directly with DC-DC converter regulating down from 14.8V down to 13.1V for the mavic would be able to supply very efficiently without much loss.

And at a rating of 10C it can output nearly 200A at full voltage, so shouldn't have a problem even charging 2-3 batteries simultaneously without breaking a sweat.

Could make a nice chassis for it out of either some aluminum extrusion, or 3D Printing something...

Hmm... (gears are turning)
 
Last edited:
Awesome article. Thanks. What was the name of the power banks please, so I can google them?
I'm gearing for and extended adventure for weeks on end using a 17w solar panel charging a 20000mah battery pack. I was also looking at linking them together but need to order the second battery first.

I've got another idea though. The output of the AC charger is 13v, 3.83amps. My battery pack outputs 12v at 4 amps and can do 16v as well. I think if I use the 16v downgraded to 13v with a dc to dc converter I'll be very close to 3.83amps at 13volts. There would be no charger in the loop though. But I think it should work.

Can you see any issues with this?
 
Awesome article. Thanks. What was the name of the power banks please, so I can google them?
I'm gearing for and extended adventure for weeks on end using a 17w solar panel charging a 20000mah battery pack. I was also looking at linking them together but need to order the second battery first.

I've got another idea though. The output of the AC charger is 13v, 3.83amps. My battery pack outputs 12v at 4 amps and can do 16v as well. I think if I use the 16v downgraded to 13v with a dc to dc converter I'll be very close to 3.83amps at 13volts. There would be no charger in the loop though. But I think it should work.

Can you see any issues with this?

The battery battery banks I used are IWO brand. Although as anything in china, there are many brands of the same product. There is a 33000 mAh pack and a 45000 mAh pack. Get the bigger one. The place I bought them was on Ebay, search for 45000 mah Laptop Charger. There is ones you will see that are 300-400 Dollars... don't buy it at that price. I am told this is done when they have no stock. The guys I bought one from was in Vancouver BC, the other one I bought from another ebay user since the first guy sold out before I could test my idea with 1 pack.
 
  • Like
Reactions: eagleeye29
This is very interesting, I was thinking of a similar situation (I have a 25AH battery bank which is configurable like this one for several DC voltages, designed for charging laptops).

When you say you hooked these up in series though... What? Seems both like a bad idea (not sure how that will affect the banks) not to mention you're essentially setting your voltage to 24v then... Is that intentional? Seems like running them in parallel would make more sense (double current carrying capacity).

I'm half-tempted to build a portable charge-bank out of a DC-DC regulator that puts out stable 13.1V (or whatever the exact charge voltage is). And has a bank of big *** batteries from hobbyking in it, going straight from the battery to a DJI charge connector (instead of going through the car charger, for more efficiency).

I know someone on here has tested it using their car with a DC-DC regulator board, and fast charged at 100W. So no reason a high C lipo wouldn't do the same, but be portable...

Anyway for now I'll be sticking to official DJI stuff, but soon the DIY spirit won't be held back and I'll start tinkering I'm sure.

Interesting experiment, thanks for sharing!

edit: One of these: Multistar High Capacity 20000mAh 4S 10C Multi-Rotor Lipo Pack

Would hold just about 300Wh, and charging directly with DC-DC converter regulating down from 14.8V down to 13.1V for the mavic would be able to supply very efficiently without much loss.

And at a rating of 10C it can output nearly 200A at full voltage, so shouldn't have a problem even charging 2-3 batteries simultaneously without breaking a sweat.

Could make a nice chassis for it out of either some aluminum extrusion, or 3D Printing something...

Hmm... (gears are turning)

Glasswalker,
Electrons are lazy, they go the easiest way, so why not to another power bank? It works, it increases the voltage, and in turn, the required amps by the charger goes down at the higher voltage. The actual voltage being sent to the mavic charger is around 32 volts, This was tested at 16.3 volts output by the battery bank with no load on it. It is regulated out, so I don't think the volts drops when under load. But I didn't test that.

With your battery pack at 14.8 volts should be able to connect direct to the mavic charger, probably want a fuse. and it will charge normally. I didn't pick using a lipo battery like this for a few reasons: (I probably would have if I had one, and chargers for it.)
- Need another specialty charger, balancing etc for charging while at home. where this battery bank uses a simple DC barrel connector
- Need yet another specialty charger for charging in car while driving, where this battery bank uses a simple DC barrel connector
- No USB charging ability to charge controller or phone, or other devices, camera's for random strangers on the hiking trail... :)
- Battery banks can be used to charge laptop, if you go hiking with your laptop? Edit some mavic videos while camping?
- That lipo battery has no protection, ie Physical protection, poke it, slip and fall on it, etc, and you got yourself a fire, hole in your backpack, melted mavic.... forest fire...
- That Lipo needs to know when it is dead, so you don't over discharge it, and that circuitry is normally on the device using it.
- The lipo cannot be charged with a 5 volt USB, like from a foldable solar panel, if you have the patience to wait for the slow 5 volt charging :)

I would have done the Lipo Battery idea if I had them, or even if I had a charger for them, but I didn't have any so the cost barrier was higher than doing this with the battery banks I picked. That one is comparable in size to the two banks I used, which are 320 Watt hours between the two of them.

As for getting a separate DC-DC regulator and not use the OEM car charger, what do you think is in the little black box? And I am sure it has more safety features than one you would build. ie over voltage protection, which is actually in the 12 volt male socket of the mavic car charger. Open it and look. and under voltage where it will stop charging when input voltage drops below its specs. The mavic car charger gets hot when in use, so that's less that went into Mavic battery, but, do you really think you can defy all the electrical theory's and build a more efficient one? :)
Besides, you will need to bring it anyways when you are driving to charge the mavic batteries in your car, so why complicate your trip by having so many different things to carry with you?
 
Glasswalker,
Electrons are lazy, they go the easiest way, so why not to another power bank? It works, it increases the voltage, and in turn, the required amps by the charger goes down at the higher voltage. The actual voltage being sent to the mavic charger is around 32 volts, This was tested at 16.3 volts output by the battery bank with no load on it. It is regulated out, so I don't think the volts drops when under load. But I didn't test that.

With your battery pack at 14.8 volts should be able to connect direct to the mavic charger, probably want a fuse. and it will charge normally. I didn't pick using a lipo battery like this for a few reasons: (I probably would have if I had one, and chargers for it.)
- Need another specialty charger, balancing etc for charging while at home. where this battery bank uses a simple DC barrel connector
- Need yet another specialty charger for charging in car while driving, where this battery bank uses a simple DC barrel connector
- No USB charging ability to charge controller or phone, or other devices, camera's for random strangers on the hiking trail... :)
- Battery banks can be used to charge laptop, if you go hiking with your laptop? Edit some mavic videos while camping?
- That lipo battery has no protection, ie Physical protection, poke it, slip and fall on it, etc, and you got yourself a fire, hole in your backpack, melted mavic.... forest fire...
- That Lipo needs to know when it is dead, so you don't over discharge it, and that circuitry is normally on the device using it.
- The lipo cannot be charged with a 5 volt USB, like from a foldable solar panel, if you have the patience to wait for the slow 5 volt charging :)

I would have done the Lipo Battery idea if I had them, or even if I had a charger for them, but I didn't have any so the cost barrier was higher than doing this with the battery banks I picked. That one is comparable in size to the two banks I used, which are 320 Watt hours between the two of them.

As for getting a separate DC-DC regulator and not use the OEM car charger, what do you think is in the little black box? And I am sure it has more safety features than one you would build. ie over voltage protection, which is actually in the 12 volt male socket of the mavic car charger. Open it and look. and under voltage where it will stop charging when input voltage drops below its specs. The mavic car charger gets hot when in use, so that's less that went into Mavic battery, but, do you really think you can defy all the electrical theory's and build a more efficient one? :)
Besides, you will need to bring it anyways when you are driving to charge the mavic batteries in your car, so why complicate your trip by having so many different things to carry with you?

Actually I'm aware of the theory, I'm an electronics engineer. I just assume with the boost/buck regulator coming off of the lipo in the power bank, depending on the type used, and component ratings, you could be putting additional strain on the regulator circuit by running them in series like that, glad it works (and honestly it will probably be fine) but that's why I was saying it just seemed "wrong" lol

Also I agree, the battery banks definitely provide a lot of the intelligence you'd otherwise need, as you said if you already had all that, (ie: I have a balance charger already, and it runs on DC 12V so I can either plug it in at home, or into a vehicle's battery).

As for the DC-DC converter, I agree, however the one in the car charger may not be as efficient. For example a good quality switching regulator shouldn't get that hot, even running 6-8A of current. So if you're finding the heat is being generated in the car charger, that's lost power. Also keep in mind most power banks have a single cell battery in them running 3.7v, which then gets stepped up to whatever output voltage you select. So they need a boost regulator to handle the output. This is why it's got a relatively low current capacity on it's output (which is why you need two, aside from overall longevity). Using a higher voltage pack, with a switching regulator, you could have far less thermal losses (and you avoid having 3 different regulators bleeding power). So yes overall I think I could design a more efficient one ;)

The real question is if it's worth the time lol...

Your point on damaging the batteries is very valid, that's why I mentioned you'd need some cheap aluminum extrusion housing, or 3D Print a chassis to protect the battery and house any additional circuitry. (and there is nothing saying we couldn't build a charge circuit that takes solar, and a 5V USB output easily into the design as well).

Anyway, just thinking, realistically I've got little enough time for flying, no way I'm likely to have time to build one of these anytime soon. And honestly I'm not likely to be away from a power source (such as a vehicle) often enough to justify it lol...

But cool project for sure, and thanks for verifying that it works! I'm sure plenty of folks will have huge use for this as a DIY solution to charging while on the go.
 
  • Like
Reactions: Brojon
The battery battery banks I used are IWO brand. Although as anything in china, there are many brands of the same product. There is a 33000 mAh pack and a 45000 mAh pack. Get the bigger one. The place I bought them was on Ebay, search for 45000 mah Laptop Charger. There is ones you will see that are 300-400 Dollars... don't buy it at that price. I am told this is done when they have no stock. The guys I bought one from was in Vancouver BC, the other one I bought from another ebay user since the first guy sold out before I could test my idea with 1 pack.

Great. Thanks very much.
 
Or you just buy a Powermonkey 12v series. Even charges a Laptop

Your monkey battery has the following specs. This essentially makes it smaller than the mavic battery itself at 33.3 Watt Hour. Did you try this device to prove it works. The 12 volt out only has a 800mAh rating, not even enough to turn on the lights! :)
And forget the solar aspect... to get enough solar to make it worth while would be a panel that is about 24x24 inches to get 50 watts at around 16 volts. That's only 4 amps about and still is not enough to power the OEM charger, or for any other off brand mavic battery charger that I have seen, they all require around 6-9 amps @ 13ish volts

Monkey Battery parameters - not sufficient and costs too much for what it is.

Milliamps Hour (mAh): 9000
Battery Type: Lithium Polymer
Voltage: USB 5V and 12V DC
Safety Features:
Short-circuit protection
Overload protection
Reverse discharge current protection
Low voltage protection

Parameters:
Input: 5V 850mAh max.
Output: USB port: 5V 1A and 12V DC port 800mAh, solar panel output 3 watts (with addition of gorilla-pad from DC output will be 5V 2A)
Battery Chemical: Lithium Polymer
Energy: 33.3 WH
Static power waste <50 µA
Total weight: 456g
 
Can anyone tell me if The Plug will work? I am lucky enough to get the backer kit and should be arriving in the next couple of weeks. Specs listed below:

PLUG - The World's Most Powerful Battery Pack

I have the Pro Edition so they said it's 250W (200Wh) 54000mAh.

Oh and I have the 40W solar to boot.
 
Do a quick comparison at 200 watt hour is 4 Mavic battery's charged. Assuming no real loss of power to heat and conversion. that cost to charge 4 mavic batteries is $330.00 Us Dollars

My two battery banks cost 160 cnd for both and they charge 7 Mavic battery's with two of the battery banks connected in series.

Sure yours has a 120 Volt out, unless you need it, why would you want to pay for something that you don't need?

Thie claim of 97.2 Watt Hour for the travel version that is "allowed on airplanes" seems to be misleading. 42000 mAh x 3.6 volts per cell = 151200 aka 151.2 Watt Hour. 160 Watt hour is the max for planes but is airline approval required. If their claim is true at 97.2 watt hour, then it will basically be able to only charge 2 Mavic batteries, and the second one will probably not be able to be fully charged.

Like I mentioned before, I liked my set up so much that I ended up buying 2 more of the battery banks, so now I have 4, and all I pad for all 4 is about 325.00 cnd dollars, and I can charge 7 mavic batteries with each pair of the battery banks. So that's 14 battery cycles, plus the 4 fully charged mavic battery's That I take. Total 18 battery cycles.

Now the problem is to charge them fast enough. I can get another charger and do 2 at a time, but as for hiking this set up works good as they charge as I walk.
 
Do a quick comparison at 200 watt hour is 4 Mavic battery's charged. Assuming no real loss of power to heat and conversion. that cost to charge 4 mavic batteries is $330.00 Us Dollars

My two battery banks cost 160 cnd for both and they charge 7 Mavic battery's with two of the battery banks connected in series.

Sure yours has a 120 Volt out, unless you need it, why would you want to pay for something that you don't need?

Thie claim of 97.2 Watt Hour for the travel version that is "allowed on airplanes" seems to be misleading. 42000 mAh x 3.6 volts per cell = 151200 aka 151.2 Watt Hour. 160 Watt hour is the max for planes but is airline approval required. If their claim is true at 97.2 watt hour, then it will basically be able to only charge 2 Mavic batteries, and the second one will probably not be able to be fully charged.

Like I mentioned before, I liked my set up so much that I ended up buying 2 more of the battery banks, so now I have 4, and all I pad for all 4 is about 325.00 cnd dollars, and I can charge 7 mavic batteries with each pair of the battery banks. So that's 14 battery cycles, plus the 4 fully charged mavic battery's That I take. Total 18 battery cycles.

Now the problem is to charge them fast enough. I can get another charger and do 2 at a time, but as for hiking this set up works good as they charge as I walk.

Ok good to know they will work. I purchased this so long ago for my camping trips but now I have another use for it. Follow up question would be if I plugged in the 3 battery charger that you can buy on Amazon (since this has a 110v outlet), can I charge all 3 batteries at the same time to cut the charge time down. I like your design because 7 batteries is 7 batteries compared to the 4 the plug can do but your design is limited to one battery at a time.
 
  • Like
Reactions: eagleeye29
simple math. That device can do 250 watt @ 120 Volt. Basically 2 amps. Watts=Volts x Amps

If the charger draws 2 amps or less it will.

If its using 60 watts per battery x 4 = 240 watts. So in theory maybe, unless the charger draws more than 60 watts per battery. The limiting factor would be that there is not enough in that battery bank to actually charge the 4 battery's full. I do not think it will because there is a loss due to heat and the efficiency. Taking battery DC volts to AC 120 volt back to DC to charge the battery is a big loss. I would expect that you can charge 3.5 battery's if they started out completely discharged.

At the end of the day, yes you are correct that I can charge one battery at a time, this works generally for hiking since it can charge while you walk. I have now two sets of the battery banks, I can buy another charger if I want or need to charge 2 at a time.

All depends on what is more important to you. Cost for battery cycles, or ease of plugging in a 120 volt charger into a lower capacity battery bank system that costs more. But like all good projects, when some solution is found for one, something comes up later when you might say, I wish I did this or added that.

I went with a system that does not convert to and from DC because of the losses. I also looked at size, weight etc. The size of the battery banks and weight is pretty much the same as it would be for the actual mavic battery's ( 7 of them or 14) but is a lot cheaper with this charging system and I can use the battery banks for other stuff as well. eg camera charging.

When you get your device, try it out, and post your results and see how many you can charge.
 
My plan was to use a lithium iron motorcycle battery hooked up to the phantom 4 car charger and advanced Mavic charger hub. Only problem I see here is that the dji car chargers require at least 13.05V to work. LiFePO4 batteries have a nominal voltage of about 12.8. anyone know if this would be a problem?

LFX09A2-BS12-battery.jpg

s-l300.jpg
 
My plan was to use a lithium iron motorcycle battery hooked up to the phantom 4 car charger and advanced Mavic charger hub. Only problem I see here is that the dji car chargers require at least 13.05V to work. LiFePO4 batteries have a nominal voltage of about 12.8. anyone know if this would be a problem?

LFX09A2-BS12-battery.jpg

s-l300.jpg
Yes, those look heavy. Have fun carrying them up the hill.
 
Lycus Tech Mavic Air 3 Case

DJI Drone Deals

New Threads

Forum statistics

Threads
130,592
Messages
1,554,175
Members
159,596
Latest member
da4o98