Development: USB-Charging Cable for Drone-Battery

[Flydude]

That sounds awesome, I would be interested. How quickly could a MA2 battery fully charge?

Have a look at the Table in Post #33: Development: USB-Charging Cable for Drone-Battery

It depends on the charger and how many watts it can supply

 

[Nanoak]

Have a look at the Table in Post #33: Development: USB-Charging Cable for Drone-Battery

It depends on the charger and how many watts it can supply

Shut up and take my money. Anything to quit hauling a stupid proprietary charging brick. It would seem like a no brainer for dji to incorporate pd charging negotiation directly into their battery management system. Must be good money in proprietary peripherals (looking at you lightning cable).
Version 2.0, 3d print a new battery case that can house the pd components?

Also, I applaud your patience as you have thoroughly explained both Power Delivery standards as well as basic electrical calculations in this context.

DM me for venmo...

 

[Piper J3]

It's amazing what people do in their "off" time. I remember when I was a kid and a neighbor was building a rowboat in his basement. I thought it can't get any better than that...

 

[Thomas B]

My Hanatora charger ($49 on Amazon) works at home or in my car (Taurus) and charges 4 M2P batteries at a time, 20% to 100% in a little over an hour while it also charges my remote. They make essentially the same charger for the MA and MM.

 

[Flydude]

My Hanatora charger ($49 on Amazon) works at home or in my car (Taurus) and charges 4 M2P batteries at a time, 20% to 100% in a little over an hour while it also charges my remote. They make essentially the same charger for the MA and MM.

my point was to make it universal usable, just like in USB ;-)

I know, there are many options out there, but nothing that will work with *any* usb-c charger

 

[Flydude]

Thanks for your support - been buried by the job but try to continue this project in the next few days!

got my parts for integrating Quickcharge so that option is also in reach!

 

[Yeunglings]

I think there is some confusion... also i don't know where you are getting your "standard of 2.5W" because that is not the case (anymore) and also relates to power drawn from an old usb-standard port off a PC. This has nothing to do with wall chargers or USB-PD.

The units and math behind electrical power is rather simple. I don't know if the formulas we use here in germany are the same in the US but the math definitely is

So the most basic formula is:

P = U * I

Where:

P == Watt U == Volts I == Amps

So just take a look at your wall charger. For USB the Volts have to be at least 5V
The Amps are typically 2A, but could be lower (10 years old maybe?!) or even higher (3-4A).

So: P = 5V * 2A and we get P = 10W

So a very very basic wall-charger without USB-PD (you really get a PD-Charger with every phone produced in the last 5 years), you get an output of 10 Watts.

Your question about the maths with 3500 mAh: the Amps say nothing without the Volts, when charging is concerned.
Yes, the Air2 Battery is rated at 3,5 Ah, the Voltage is around 11.55 V so we get 11.55 * 3.5 = 40.425 Wh (Watt-Hours), aka the capacity.

So, if you charge with 10 Watts for 1 hour, you have charged 10Wh. To charge 40.425 Wh, you need 4 hours. Pretty simple.

The beauty of USB-PD is, that we don't have to charge with 5 Volts and 2 Amps but can ramp that up alot.
Imagine: The Amps stay at 2A but the Voltage is increased from 5V to 15V. So instead of 10 Watts we get (15V * 2A) 30 Watts. The charging time is now only (40Wh / 30W) 1.33 hours.

and as @tcope already mentioned, USB-PD is rated up to 100 Watts. Far more than the 38 Watts of the official DJI charger.



That i cannot say for sure right now. as this is only a prototype, all the materials (excluding my work) are around of 40 Euros. Far too high to make a sellable product. But with alot of tweaking i can get to a far (!) lower production price, let alone the fact of mass producing this at my business partners in china.

It would be interesting to know what your maximum price tag would be.

Thanks to all!

Personally I would probably be in for a 40-50 EURO price tag depending on build quality and shipping to the US.

 

[Gregtay67]

Would definitely buy one!

 

[DanMan32]

My Hanatora charger ($49 on Amazon) works at home or in my car (Taurus) and charges 4 M2P batteries at a time, 20% to 100% in a little over an hour while it also charges my remote. They make essentially the same charger for the MA and MM.

Not likely you can charge 4 M2 batteries from a 12v outlet. The DJI stock 12v charger draws 6A @ 12v which is 72W.
If you're charging 4 of them simultaneously, that would be 24A or 288W. Few if any 12v outlets are wired to provide that much current/watts.

I suppose an inverter hard wired to the car battery might work.

 

[Thomas B]

Not likely you can charge 4 M2 batteries from a 12v outlet. The DJI stock 12v charger draws 6A @ 12v which is 72W.
If you're charging 4 of them simultaneously, that would be 24A or 288W. Few if any 12v outlets are wired to provide that much current/watts.

I suppose an inverter hard wired to the car battery might work.

It works as stated above without any modifications to house, charger or car.

 

[Yeunglings]

I'd gladly buy one, or more to do 2 different drones, and if you were able to make just a barrel port adaptor cable too that would be awesome. I have an Omnicharge and Omnicharge ultimate where I can dial in voltage and amperage and max out at 150w dc but also has 60w usb c and 120w AC out to boot. They used to make a barrel port adaptor for the mavic pro but stopped after that for some reason. With a MM, an MA2 and soon either a M2Z or M3(whenever that finally gets anounced) I'd love to have a one stop charging option in my kit.

 

[Pappy]

If you're charging 4 of them simultaneously, that would be 24A or 288W.

The Hanatora charger only applies up to 2.0 amps for charging current per battery whether it's on AC or DC. Here are the specs from the User Manual

 

[Flydude]

sorry, have been busy with work and another project that needed attention.

i have now 3 inputs in my latest prototype:

USB-PD (up to 100 Watts)
USB-QC 3.0 (up to 36 Watts)
USB-A (up to 20 Watts)

I could easily replace the Quickcharge 3.0 with a QC 4.0 Converter, which would also allow up to 100 Watts like PD but the cost for that component is really high. Also i don't have any QC 4.0 Charger lying around, so i am sticking to QC 3.0 as the 36 Watts (max!) correspond to the original DJI charger and the Power-Output will be capped to that anyway for safety.

Also have been talking to many people regarding a FCC/CE certification, but this is real complex, and takes alot of time/money.

Will report back as soon as i have the opportunity

 

[rmrf]

sorry, have been busy with work and another project that needed attention.

Sorry. Just jumped at this MA2 wagon and figured out stupidity of battery charging market here.

I have couple of questions about your project.
Did you reverse engineer all pins? I believe there is something more smarter than just Vcc/Gnd.
Which module do you use to produce constant charging voltage? I assume for PD I can have something like this: https://amzn.to/2Jd4Lqo, but USB-C cannot guarantee lets say 15V, so I assume there is should be some step-up/step-down converter.
Is there available ready-to-eat barrel to MA2 battery cables on the market from your post above? Is there any available connectors to make one without brutalizing some charger?

Thanks

 

[Flydude]

Is there available ready-to-eat barrel to MA2 battery cables on the market from your post above? Is there any available connectors to make one without brutalizing some charger?

you can randomly check aliexpress if they are selling those to the public. there are some battery cables available for older DJI drones.

I am sourcing my cables from another factory directly in shenzen, not available to the general public - sorry

 

[Yeunglings]

Just popping in to see if there's any news on your project. I may jump on the hanotora charger for $60(~42€)but that only solves the problem for 1 drone and needs AC or 12v cigarette lighter port where as I see the potential for this to be much greater. Buy a 'base' unit with usb in, maybe barrel port too, with interchangeable output connectors for various different drones. Assuming, all things being equal, I'm willing to drop roughly $60 per drone configuration(MP, MA2, M2Z etc) to be able to charge on the go but now am carrying a ton of extra equipment I think a totally universal and upgradeable/ interchangeable with a 'base' price for say $80, maybe a discounted first connector at $20, and each different connector for $30 would be great. Say i buy this for my MA2 at $100 for the whole kit. Pretty pricey I know but down the road I get a M2Z. Do I shell out $60 for another hanotora( I'm at $120 between both drones and carrying 2 setups in this scenario) or do I buy an extra tip for your unit bringing me to $130 and a much smaller kit. I can only fly 1 drone at a time so its not like I NEED to always be charging both styles at the same time. Or say I sell my current drone and start all over with something new, 8 just buy a different tip for $30 saving me cash.
Having said all that even as you've described it so far as just being able to take usb in and convert it in to usable MA2 charging power is worth at least the same, if not more, than the cost of the Hanotora because of its inherent flexibility

 

[DanMan32]

Standard USB C cable can carry 100 watts.

Depends on the volts. 100w with standard 5v would be 20A. Thats a lot for thin wires. Even if the cable can handle it (though few chargers would deliver it), the wire will quickly be stressed and break. It would get pretty hot too.

Volts need thicker insulation (though at the voltages we're talking about, doesn't matter), higher currents need thicker conductors.

The BMS in the smart batteries will limit the current drawn so no need to limit it at the charger, which is not much more than a power supply. I'm not sure if the batteries for either Mini have charging control built in, or if that's handled by the AC/hub.

For the M2 stock chargers, the car charger charges faster than the AC charger as the AC charger is 65W, while the car charger draws 6A during charge, so 72w. You can't go much faster than car charger, battery won't let you.

 

[DanMan32]

I used to think that QC chargers would go to 12v for rapid charge. All my QC chargers are rated 5,9 and 12v.
Except for Samsung 15w chargers, they only output 9v

I bought a USB charging meter and was surprised at the results.
My HTC 10 negotiated 7v and drew sufficient amps to receive about 15W.
Samsung Tab S3 and S20 FE negotiated 9v with current for 15w. The S20 FE is rated to charge as fast as 24w, but not with QC. You have to use PD.

My RavPower power bank was the only device that would draw 20w but not at 12v as I thought it would. I think that too was 7v, and you have to use the micro charge port for QC. The bidirectional C port it has is fixed at 5v.

QC 2.0 has fixed voltages ( 3.3v and 0.6v) based on the voltages placed on the data lines acting as ones and zeros.

QC 3.0 starts out using QC2 with data voltages in a combination not in QC 2 specs. Then the data lines are pulsed to increase or decrease the starting voltage by 0.2v, much like pushing a volume up, volume down button.
I think my HTC 10 used QC3 to negotiate 7v, but the meter didn't recognize the patterns so it shows as unknown standard. Obviously my chargers understood.

 

[Flydude]

Just popping in to see if there's any news on your project. I may jump on the hanotora charger for $60(~42€)but that only solves the problem for 1 drone and needs AC or 12v cigarette lighter port where as I see the potential for this to be much greater. Buy a 'base' unit with usb in, maybe barrel port too, with interchangeable output connectors for various different drones. Assuming, all things being equal, I'm willing to drop roughly $60 per drone configuration(MP, MA2, M2Z etc) to be able to charge on the go but now am carrying a ton of extra equipment I think a totally universal and upgradeable/ interchangeable with a 'base' price for say $80, maybe a discounted first connector at $20, and each different connector for $30 would be great. Say i buy this for my MA2 at $100 for the whole kit. Pretty pricey I know but down the road I get a M2Z. Do I shell out $60 for another hanotora( I'm at $120 between both drones and carrying 2 setups in this scenario) or do I buy an extra tip for your unit bringing me to $130 and a much smaller kit. I can only fly 1 drone at a time so its not like I NEED to always be charging both styles at the same time. Or say I sell my current drone and start all over with something new, 8 just buy a different tip for $30 saving me cash.
Having said all that even as you've described it so far as just being able to take usb in and convert it in to usable MA2 charging power is worth at least the same, if not more, than the cost of the Hanotora because of its inherent flexibility

Thanks for your input!

The project is currently stalled due to multiple factors:

- been too busy with my primary job so i had to pull back on projects
- waiting for answers from lawyers for this project (more down below)
- thinking about in which direction i want to move

The current status:

- USB-PD works flawlessly. You can use probably any charger you want. Tested it with multiple chargers with 5, 9, 12 and up to 20 Volts. The maximum output is 35 Watts, defined via my firmware which limits the maximum current. So even that is adjustable, all via software

- USB-QC works well, but has not been tested as much. I only have chargers with 9 and 12 Volts at hand. Up to 20 Volts should be possible. I have my own custom chip with software which negotiates the voltage in 200 mV steps. The whole circuit can cope with any voltage applied to it and puts out stable 13.2 Volts for the mavic air 2.

- i added another chip ("esp" if you are interested) which controls voltage, current and temperature and activates a very small fan if anything gets too hot. Also this chip has bluetooth support, so in the future everything can be controlled via a simple android or iOS app on the smartphone (the app is not built yet, but that is rather easy).

The whole adapter is within a small 3d-printed case and has 2 USB-C inputs, one for USB-PD and the other one for USB-QC. I have not yet succeeded in combining both technologies reliably on one single USB-Port, so that's why there are two of them. If, for example, you attach a USB-PD charger on the USB-QC port, nothing bad will happen, the voltage will be limited to 5 Volts and Amps will be pretty low.

Then there is another Micro-USB Port, this one is only used for upgrading the firmware. Might not need that one, but i wanted the system to be upgradeable.

On the other side is a standard round jack, so almost anything can be connected.
I.E. i use that to attach the connector for my acer-notebook an can charge that (with 19 Volts) via my prototype-adapter. Just FYI: this is my 14th build of this adapter, as i modified it alot ... ;-)


Now on to the problems:

As i am doing a DC-DC conversion here, there are some rules. Most probably the adapter needs a CE (Europe) and FCC (USA) certification.

The CE-Certification is a little bit harder as the FCC counterpart, so by getting CE certified, the FCC will most probably be also given.

The certification process is very expensive - we are talking somewhere between 5.000 and 10.000 Euros (6.000 - 12.000 USD).
So currently i cannot simply do that - the customer base is too small. Also there is a high possibility, that my design will be copied by another company (not making a political statement here) and producing everything in china without certification and selling that via alibaba or banggood worldwide.

I only see two possible roads:

- going for a kickstarter/indiegogo to get enough backers and the money for the certification.
- going full opensource and releasing everything to the public, so that everyone can use the current DIY-Methods to create the adapter

With the first option i might get some buck for my invested time (hundreds of hours) while with the second one i will be doing something good for the community and might get some donations.

I am still not sure which way to go ... need more time to think about it.

 

[Flydude]

and yes, the output is a standard barell 2.5mm connector. one can easily switch to another drone, just need to replace the connector. for Mavic Pro2 the output voltage is higher, but this can be configured in software, so the adapter can output that aswell. up to 32 volt output is possible, even if you would just use an old adapter without PD or QC that only delivers 5 Volts