Wireless charging - particularly booster packs or headlight packs

[KirstinS]

Powermat wireless charging matts are now ridiculously cheap. I paid 7.99 delivered for a mat that can charge 3 devices at once and a universal receiver coil. I also then paid 99p for an old ipod touch receiver case as well.

I stripped the induction coil out of the iPod case and wired it to a 3.7v 18650 cell. When placed onto the mat the 18650 charges just fine as expected – after all 99% of phone batteries are 3.7v lithium

I’m thinking if I get 3 induction coils and wire one coil into each of the series on my 3s booster pack I could wireless charge it. Just plonk it onto my 3 device mat and off it charges. Of course a 3s booster battery will use all three of the charge points and the coils will need to be position on the pack correctly. None of which is rocket science. In fact this would not just be wireless charging but wireless balance charging !

Not quick, not efficient but cool, albeit in an uber geeky way, that I rather appreciate. And for a total cost of £10.97 which I really appreciate 

Once you have a charging matt it seems to me that pretty much any 3.7v lithium gadget could have a wireless induction coil added for under a pound (or 7.4v gadets such as lights for under £2) My ereader is next on the conversion list as I’ve already converted my iphone (just added the induction coil to the protective case I use).

cheers
Kirstin

 

[pdarnett]

I was thinking something on the garage floor and just park the bike! But like how you think I may have a play with some.

 

[Alan Quay]

Is that powermat a charger or a power supply? What I mean is, will the powermat stop charging when the current drops off, or does it expect the device to manage the charging?

 

[KirstinS]

I was thinking something on the garage floor and just park the bike! But like how you think I may have a play with some.

Problem is the distance can only go to about 5mm max !

 

[KirstinS]

Is that powermat a charger or a power supply? What I mean is, will the powermat stop charging when the current drops off, or does it expect the device to manage the charging?

It's smart / charger - it won't over charge a cell or device and stops transmitting when full

http://www.duracellpowermat.com/powermat

 

[Alan Quay]

It's smart / charger - it won't over charge a cell or device and stops transmitting when full

http://www.duracellpowermat.com/powermat

If that's true then it's a great idea. I think I'd want to stick a meter on it to be sure though....

 

[Geebee]

They are less efficient than direct connection and looking at the access case it is using the normal charging socket as input which suggests that the device controls cut off.
I would try measuring a few batteries over a few charges before deciding that it has 4.2v cutoff.
Just had a quick read around and most seem detect cut off by the device being charged terminating charge not the mat.

 

[KirstinS]

They are less efficient than direct connection and looking at the access case it is using the normal charging socket as input which suggests that the device controls cut off.
I would try measuring a few batteries over a few charges before deciding that it has 4.2v cutoff.
Just had a quick read around and most seem detect cut off by the device being charged terminating charge not the mat.

I'll test this theory and report back !

 

[KirstinS]

Wellthere are a couple of problems with my idea !

1.) seems geebee is correct. The powermat acts as a psu, specifically as USB psu and not a charger I.e will not itself cease charging. Which leads to problem 2
2) the output from the induction is coils is USB level I.e 5v not the requesite 4.2v


I have a hack it together style solution

At Xmas I gave out these to folk as stocking fillers with my best harvested 18650 cells

http://www.ebay.com/itm/1A-USB-Power-Bank-18650-Battery-Charger-DIY-Box-for-Mobile-iPhone-5S-5C-5-Note-3-/261335400180?pt=LH_DefaultDomain_2&var=&hash=item3cd8cdbef4

Not these exact but basically the same for 99p each delivered.

Inside is a small chip size of a fingernail with micro USB input, a normal size female USB output.

If wire this in as well as each coil then it will achive three things

1) step down 5v to 4.2v
2) prevent overcharging as it has a circuit that cuts the power to the battery when full
3) could also act as a USB out enabling the booster battery to be used to charge any USB device.


I do fully appreciate we are in the realms of why to people climb mountains (because they are there) and not in the realms of sense or practicality

Still I'm going to give it a crack. I'll report back when complete or at the next hurdle ,