i thought with a transfomer you could get it to produce a desired voltage with different thickness of wire and the important part was the two coils ratio of windings to each other. you could bump everything fatter for higher current. .
9mm is pretty far considering you could just put them 1mm or closer. even at 1amp that would be good enough to charge through the night…and maybe heat the room a bit too.
I think it’s pretty much just a transformer with a rectifier. comes out of the wall ac at 120 get that converted to 4 volts.
this would be cutting the voltage way down and the amperage would go way up in the transfomer and just cut it to dc at the right frequency. this is my huge simplification of what I think is done
Ours is 9mm because we have to count the wall thickness or our enclosure and the double water seal to ensure that nothing gets in. Trying to get it down a bit.
Yes, you should look up these ‘‘3d charging pads’’ They are like a bowl and I believe you put multiple devices into them… the devices of course need to have receiving coils built into them (usually in the case)
Looks like this could be more mainstream incorporated in the future… the prices need to go down of course but that idea of just placing multiple devices onto a pad and leaving them there seems very conveniant… no need to find charger for each device, if it can tuned in such a way that each device receives how much it needs.
Btw, it looks like the big guys had beem working on this for a while:
maybe u we’re doing something different as these must stop charging at the max charge. That’s how they’re designed or people would be blowing up their stuff left and right. My power supply I set it to a voltage and that’s as high as it will charge the cells. No current flows if there’s no voltage difference
Why do u say 3 receivers on each cell? I’d think one
This is something that can be experimented with for little investment and much is already done. I’m going to simply get a couple of those receivers and take them to Starbucks or wherever else they have a qi pad with my multimeter and see if I can get them to work stacked.
Your video the tech is much harder to use than simply inductance charging which is simply a transformer. I’m still unsure how they transfer the energy as typically a transformer has both coils on the same core and the qi is completely flat so no second coil is being looped over a core on the first coil. But still pretty sure it’s the same basic tech as done on toothbrushes and just induction charging.
@Eboosted you really picked out / chose the best details / picture from this thread! lol
Besides… his idea is not that bad… will find about one of evolve’s guys who made a similar looking thing to charge his board just by ‘‘stacking it’’ into place or something…
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@Hummie I like your idea! Please do so, if you can source them quickly! China is way too far from me and will take too much time to do that + I dont really trust these little coils yet… I think to achieve some better result there will be a need to make some custom, perhaps different wire and diameter coils for better power output -
Though - I will agree that these are quite cheap, ready to use… and for experiment they are totally okay! Just to see, if they can be stacked or what is the minimum distance they need to be from each other not interfere… – Fast forward – I like the idea about the charging mat - it should provide the possibility for multiple receiving coils close to each other
So basically, just report back once you get some more info about whenever it works or not!
I will try to ask around and contact some more manufacturers or company’s who are dealing with wireless technology… I dont expect that they will give out their intelectual property right away… but perhaps there can be a deal or some sort of mutual agreement made with them…
i’m all over this and on hold with texas instruments. trying to get someone who can dumb it down for me.
I think stacking the standard receivers won’t work as they’re shielded to get better coupling. maybe cut the shielding off though. or another coil. who knows but texas instruments is going to respond by email to tech questions.
You really should learn basics of electrical engineering, EMF, resonant circuits and other stuff related to this topic before you begin to work on it. Doing something without understanding how it works and which problems / dangers it introduces is just stupid. You will end up having non working device or blow something up ( unless you use a pre made solution ). You should also buy an oscilloscope for debugging those kind of circuits. You will also need a BMS in the board.
easy reading those links are
“Resonance is a property of an oscillating system which drives another system to oscillate with a greater amplitude at a designated frequency. For example, if you have two tuning forks that respond to the same frequency, by playing one fork the other tuning fork will begin to vibrate due to resonance. This same property is achieved in electrical systems through resistor, inductor, and capacitor (RLC) circuits.
Weakly coupled magnetic resonance, although less energy efficient, reduces the proximity requirements of inductive charging. Nikola Tesla was famous for his experiments using the electromagnetic field (EMF) of the Earth’s ionosphere in an attempt to distribute energy. Similarly, magnetic resonance (non EMF) relies on magnetic fields but allows primary and secondary coils to have fewer magnetic field lines in common. This increases the system’s spatial freedom, allows the coils to differ in shape and size, and allows multiple devices to charge from a single source, establishing a one-to-many relationship.”
but not the resonant energy but plain inductive energy transfer and using 12x12 coils, that i think will top the voltage on each cell and put it on simmer
what’s missing?
can’t find those 2$ receivers anywhere locally, today, and will get it shipped but regardless will likely need the bit linked right above and it’s included inside a phone.
or forget most of the complication and get these and then just need to supply 12v dc to primary coil
very tempting. but what’s the deal with the 5v and does that mean I wouldn’t get the cc cv id like for the lithium chemistry? i think so …so how to add that other part i linked?
"This is a basic charger set, and it does work, providing 5V DC output from the output half when the input half is powered with 9V to 12VDC. You can draw as much as ~500mA if the coils are 2 or 3 mm apart. "
so only half an amp is coming out of these at 5 volts, so only maybe 3 watts, times 12 cells with chargers. 40 watt charging. too slow for me with a 250watt hour pack but if the battery were much bigger these could still be ideal. slow charge a big pack you drained through the day and charge it overnight while you slept.
if i were to set it up on my board i wouldn’t even need a switch to turn it on anymore, just keep the esc in constant ON hard wired and leave the board on it’s cradle all the time. no switch needed. and definately no bms. no plug. !! waterproof to the extreme. plus a million other plusses.
@devin I assume you like do calculations and this was one more area to express yourself… so I assume I should say thanks for throwing in some numbers for this one!
Can you explain the ‘‘Pulsed DC current part’’?
I understand that receiver coils receives AC current, which then needs to be rectified and smoothed out to DC current once again… but im not sure is this the same thing you mentioned.
Your idea about ‘‘inserting a iron / ferrite rod between the coils’’ is also not that bad I think!
Perhaps it could be done in a manner similar like this:
Deck itself contains the coil, perhaps there is some sort of ‘‘hole’’ / opening to accomodate the iron core, for increased efficiency. Iron core would be sticking out of the transmit pad…
Size minimization for coil and other electronics - embedding in the deck.)
(no iron core through the coil)
Just some kind of little ‘‘lump’’ for the sending coil to be able to be closer to the receiving coil. I made this in a somewhat oval shape, but the opening could be something similar like car 12dc jack, - ‘‘barrel style’’
(sorry for the rough drawings)
Btw - I actually imagine doing something similar (with barrels / big contacts) if this wireless idea cannot fruit now… For dc contacts part the only problem would be to secure them / protect from the weather - water, while at the same time making them easy to use… so no fiddling around them would be needed! But this still would not be as nice solution as the wireless system, where the board just should be put in the right position and left there…
you really picked out / chose the best details / picture from this thread! lol 
