Development: USB-Charging Cable for Drone-Battery

[Yeunglings]

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.

Wow, you have been REALLY busy. Thanks for letting me/us know and for all your hard work. I had thought about suggesting kickstarter or indiegogo but don't know the ins and outs or how you wanted to do things. As this lifestyle and community are becoming more important to me and my family( the kids and dog really love flying) and what you have been working on seems to have the potential to make everyone who's interested life easier if you were able to come up with a real kickstarter project i would definitely buy at least 1 kit as roughly described, maybe 2 depending on my needs, as well as contribute as a pure donor. I've seen where there are sometimes flex goals where if certain thresholds are achieved then new options are available, sometimes free due to economies of scale or sometimes as a paid upgrade. I have no technical or business acumen so I cant help other than to be a cheerleader and to spread the word but ill do both?

 

[DanMan32]

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

Just note that the bigger Mavics and all the Phantoms need at least 50-70w at the proper voltage. About 4.2v - 4.4v per cell. Too little wattage and the batteries will take forever to fully charge.
You rated the max output using a PD charger at only 35w which would take roughly 3 hours for a single M2 battery.

 

[Flydude]

You rated the max output using a PD charger at only 35w which would take roughly 3 hours for a single M2 battery.

no, i limited (via software) the wattage on purpose to 35 Watts to be as close as the original MA2 charger.

The system can easily supply the full 100 Watts of USB-PD if configured that way.

 

[DanMan32]

Well you were working on this being a universal charger.

The smart batteries should only take the maximum current allowed. The charge control is in the batteries themselves.
That probably isn't the case with the Mini batteries though.

I would be concerned about the universal charger being mis-set by the user for the battery being charged.

 

[Flydude]

That probably isn't the case with the Mini batteries though.

i wouldn't want to use this on the mini(2) ever.
Especially the mini2 already has USB-C Input and also allows USB-PD - i.e. it switches to 15 Volts and 2 Amps if i connect a nintendo-switch power-supply.

Nothing to be gained by using my adapter at all as DJI implemented this strategy on the drone itself.

I would be concerned about the universal charger being mis-set by the user for the battery being charged.

this seems an edge scenario. only for people who would really have two distinct power levels needed (i.e. air2 and pro2).
Those could be switchable via profiles. Even more the adapter could force a user confirmation if it is unsure if the voltage can be safely applied.

example #1 with air2:
current battery voltage is at 10 Volts (~ 27%), but the adapters profile is set to pro2 (charge with 17.8 Volts; 4 cells). The adapter will deny the profile because the voltage cannot correspond to a 4-cell battery.

example #2 with air2:
current battery voltage is at 12.5 Volts (~ 97%). The adapter could charge but is not sure if this is a 3-cell battery at 97% or a 4-cell battery at 10%. So it will ask the user for confirmation if this is indeed a 4-cell battery.

There is only a small margin where the adapter would not detect the battery itself and needs confirmation, but this is a pretty usual way of doing it (like the IMAX Balancers do).



But as i stated above, i will not think about implementing new features right now.
First the next steps (Opensource or Crowdfunding) have to be decided. Also, i want to spend some more time with my kids, so i will go into hiding for the moment.

 

[DanMan32]

I thought you were designing this to charge the batteries themselves, rather than relying on a built-in charger that only needs a suitable USB power.

 

[Flydude]

I thought you were designing this to charge the batteries themselves, rather than relying on a built-in charger that only needs a suitable USB power.

Please do read the thread again, especially my initial posts.
Almost everything is covered there.

Also, this alsways has been a project to charge the bigger drones like air, air2, mavic pro, pro2 etc.

the mini2 was just an example where *not* to use the adapter as it is useless. the bigger drones *do not support* usb-charging, not even considering the high wattage USB-PD and USB-QC are providing and that is basically the idea.

 

[Yeunglings]

I think what Flydude is saying is that the unit he's designing is to convert usb powerbanks in to usable power sources other than wall AC for the drone batteries at various ratings. Picture it this way, your wall charger for your phone isn't really a charger, it's just converting 120/240ac in to DC in the overall usb standard spectrum. You could take the cable off and plug that in to any other charger or laptop or what have you. Power Delivery and Quick Charge are special circumstances though. Your phone is usually what does the heavy lifting of charging at its specific needs. For your drone that isn't the case. That charging brick is taking the 120/240 AC and converting that in to a very specific DC voltage, amperage and so on using a unique connector. His unit would combine both concepts together and do all the heavy lifting of converting any( or almost any) usb source into the drone specific needs based on which connector you plug in other than maybe letting you know you need to slide a switch or push a button.

 

[Flydude]

@Yeunglings thanks for your reply!

Perfect explanation! and i am lacking the gentle words today as i am still fixing the ******* dishwasher. it is driving me nuts ;-)

 

[Yeunglings]

@Yeunglings thanks for your reply!

Perfect explanation! and i am lacking the gentle words today as i am still fixing the ******* dishwasher. it is driving me nuts ;-)

I told ya I'd be your cheerleader and spread the word? of course I'm kinda stupid so I may not always spread the right word.

 

[DanMan32]

I think what Flydude is saying is that the unit he's designing is to convert usb powerbanks in to usable power sources other than wall AC for the drone batteries at various ratings. Picture it this way, your wall charger for your phone isn't really a charger, it's just converting 120/240ac in to DC in the overall usb standard spectrum. You could take the cable off and plug that in to any other charger or laptop or what have you. Power Delivery and Quick Charge are special circumstances though. Your phone is usually what does the heavy lifting of charging at its specific needs. For your drone that isn't the case. That charging brick is taking the 120/240 AC and converting that in to a very specific DC voltage, amperage and so on using a unique connector. His unit would combine both concepts together and do all the heavy lifting of converting any( or almost any) usb source into the drone specific needs based on which connector you plug in other than maybe letting you know you need to slide a switch or push a button.

Then we're back to most powerbanks incapable of outputting via USB the watts to charge the bigger drone batteries in a reasonable time (M2 batteries typically charge 60W or more), and for the user to misconfigure the output voltage for the battery being charged. You don't want to mistakenly set M2 battery voltage when charging an Air. Current limit setting is another concern though less so, since the intelligent batteries should only draw the maximum current they're designed for.

Perhaps if the battery adapters for the particular battery would tell the charger what the appropriate voltage and optional current should be. It has to be fixable by firmware though in case it's wrong.

 

[Yeunglings]

Then we're back to most powerbanks incapable of outputting via USB the watts to charge the bigger drone batteries in a reasonable time (M2 batteries typically charge 60W or more), and for the user to misconfigure the output voltage for the battery being charged. You don't want to mistakenly set M2 battery voltage when charging an Air. Current limit setting is another concern though less so, since the intelligent batteries should only draw the maximum current they're designed for.

Perhaps if the battery adapters for the particular battery would tell the charger what the appropriate voltage and optional current should be. It has to be fixable by firmware though in case it's wrong.

I'm no electrical specialist or engineer but I do have a bunch of easyacc powerbanks that I can charge my laptops and chromebooks on. They're only rated at 5v3a( so ~15w)but my devices that are rated for 45-60w and charge fine. Slower for sure but fine. I also, and I'm sure I'm in a minority but......, have powerbankss made by omnicharge with usb c rated at 60w and barrel ports that I can dial in to any number of watts and amps. There are also plenty of other powerbanks out there that offer similar capabilities. For me, if this can do what I think it can, this could be a gamechanger. I pack 1 powerbank rated for 142wh and his adaptive charger along with connectors and what I already have and I could theoretically charge my MM, Mini2, MA2, all controllers and the next addition to my fleet all at the same time from 1 unit.

 

[DanMan32]

I'm no electrical specialist or engineer but I do have a bunch of easyacc powerbanks that I can charge my laptops and chromebooks on. They're only rated at 5v3a( so ~15w)but my devices that are rated for 45-60w and charge fine. Slower for sure but fine. I also, and I'm sure I'm in a minority but......, have powerbankss made by omnicharge with usb c rated at 60w and barrel ports that I can dial in to any number of watts and amps. There are also plenty of other powerbanks out there that offer similar capabilities. For me, if this can do what I think it can, this could be a gamechanger. I pack 1 powerbank rated for 142wh and his adaptive charger along with connectors and what I already have and I could theoretically charge my MM, Mini2, MA2, all controllers and the next addition to my fleet all at the same time from 1 unit.

For the smaller Mavics with smaller batteries, that could be practical with average powerbank with low wattage (
Take your 5v3A one for example. That's 15W.
The M2 battery takes 90 minutes at 60W to fully charge. That's about 90WHr capacity of the battery. To charge at 15W would take 6 hours! And that's for ONE battery. I'd rather bring the appropriate charger and power source than wait 18 hours to fully charge 3 M2 batteries.

 

[Korrd]

OMG, this is awesome.
I was looking into this, but my approach was to modify a car charger to accept a wider range of input voltages, as a car charger is pretty much a switching power supply acting as a regulator.

Do you intend to commercialize this, or open-source the schematics?

 

[Yeunglings]

Then we're back to most powerbanks incapable of outputting via USB the watts to charge the bigger drone batteries in a reasonable time (M2 batteries typically charge 60W or more), and for the user to misconfigure the output voltage for the battery being charged. You don't want to mistakenly set M2 battery voltage when charging an Air. Current limit setting is another concern though less so, since the intelligent batteries should only draw the maximum current they're designed for.

Perhaps if the battery adapters for the particular battery would tell the charger what the appropriate voltage and optional current should be. It has to be fixable by firmware though in case it's wrong.

For the smaller Mavics with smaller batteries, that could be practical with average powerbank with low wattage (
Take your 5v3A one for example. That's 15W.
The M2 battery takes 90 minutes at 60W to fully charge. That's about 90WHr capacity of the battery. To charge at 15W would take 6 hours! And that's for ONE battery. I'd rather bring the appropriate charger and power source than wait 18 hours to fully charge 3 M2 batteries.

Im not sure if thats necessarily true though about the powerbanks. Again Im not claiming to be even average when it comes to electrical knowhow and have no inside knowledge of how this unit would really work but the smaller banks that I have, the 20k and 26k mah units, all allow for the 5v3a on each of its 4 outputs at the same time so if there were either multiple inputs on Flydudes charger or someway of using an external adaptor to combine them these could theoretically supply 60w; these powerbanks all have dual inputs for charging quicker so I would think something similar could happen here. and for those of us with omnicharge , goal zero, anker powercore and other such units that are already capable of delivering 45 or even 60w via usb c PD and in the case of the omni, its what i have and have easiest access to info for it, I can do up to 150w DC via barrel port so I can plug in a cigarette adaptor and then use that in addition to the usb , usb c and AC output.

 

[amb9800]

Then we're back to most powerbanks incapable of outputting via USB the watts to charge the bigger drone batteries in a reasonable time (M2 batteries typically charge 60W or more), and for the user to misconfigure the output voltage for the battery being charged. You don't want to mistakenly set M2 battery voltage when charging an Air. Current limit setting is another concern though less so, since the intelligent batteries should only draw the maximum current they're designed for.

Perhaps if the battery adapters for the particular battery would tell the charger what the appropriate voltage and optional current should be. It has to be fixable by firmware though in case it's wrong.

There are plenty of high-wattage USB-C PD batteries available for those want them - up to 100W per port (which is the max PD provides for). Of course, the vast majority of mobile computing devices don't require that much, hence lower output options being more popular.

 

[donbernardo]

This is truly amazing. Just discovered the post today. I'd almost given up on something like this. I went on a 6wk cycling trip in Iceland in 2019 and carried a GoalZero Sherpa 100AC and a Nomad28 solar panel as I did stealth camping mostly. This solution would be a simply fantastic.

Thank you flydude for all your troubles and your perseverance! Good luck, whichever route you'll take!

 

[anotherlab]

....

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.

If you go the Kickstarter route, either there will be enough backers to pay for it, or the campaign fails and no one is charged. The advantage to you is finding out if there is enough demand for the product. If the campaign does take off, you'll have a brief window of time before a clone shows up on one of the usual suspects.

Have you thought about licensing it to a company that does drone accessories, like Pgytech?

 

[Yeunglings]

Just popping in again to see if there have been any developments. I decided to hold off on the Hanatora charger a little longer so I could throw my money your way instead ?

 

[Flydude]

sorry for the delay, it has been very hard to focus and to get everything on the way.

Very special thanks for your support! If you need a quick solution i suggest to buy a hanatora charger, as the kickstarter-project seems to be far away (mostly due to legal issues).

So instead, i will release all relevant information as open-source (most likely on github). This will take some additional time as i will try to compile a list of items that can be bought on aliexpress/mouser so that everyone with a soldering iron and an arduino-ide can build the system.

@Yeunglings: if you want to be the frist to try, please PM me
For everyone else: it is not really hard, the coding has been done and all components should be readily available. But it requires some soldering.

so please, decide what you want, buy a charger or build it yourself (and invest some time) - maybe even perfect it on the way. I am a strong supporter of opensource as the swarm intelligence of many humans improves things (at least that is my opinion).

Best regards!