Inductive charging of a Lipo

Steve2381

Senior Member
Hello folks

I know best part of nothing about batteries, so this is all new.
We need to charge a tiny Lipo battery like this...

http://www.adhiratech.com/index.php?route=product/product&product_id=2514

and I was thinking of controlling that charge with one of these...

https://uk.rs-online.com/web/p/battery-charge-controller-ics/8895871/

Its going to have an 08m2 attached, and not have to last long on a charge (a matter of minutes).

But, its going in a waterproof enclosure, so charging the battery is the issue.
Anyone attempted making an inductive charger for a Lipo? Is it even within the realm of realistic to contemplate?

Your views gratefully received!
 

Steve2381

Senior Member
Yes... I just found that page. I like the idea of the PCB having the charging receiver induction loops etched into it.
 

Steve2381

Senior Member
Throwing the idea out there... and I have NO idea if it would work...
This unit is small, do you think if you surrounded the pcb in a coil, you could spin a magnet at high speed around the finished device (in close proximity) and induce a reasonable charge within the coil to be rectified and used to charge a 3.7v Lipo?
 

hippy

Technical Support
Staff member
I don't know a lot about LiPo batteries and even less about wireless charging but I would suggest looking for a pre-built combination which, on one side, delivers the charge, and on the other charges and delivers 5V or whatever to an attached circuit.

In theory it seems easy; as you say, spin a magnet, use the voltage induced in a coil to charge the battery, but there's probably more to it than that.

If you are going to DIY I would suggest at least starting with a commercial wireless charger plate, and use that.
 

erco

Senior Member
If you want another long-term experimental project, spin that magnet. It may be possible but there is likely a reason no one else does it that way. Moving parts wearing out, noise, etc.

If you want a quick solution, go with Sparkfun.
 

Pongo

Senior Member
I think a problem with the spinning magnet is that you'll need a lot of turns on the receiving coil, unlike the much higher frequency electronic solutions. It will also be very inefficient.
 

hippy

Technical Support
Staff member
Note that as well as the wireless charge transmitter and wireless charge receiver, you will need an additional module to allow the LiPO to be charged and used safely.

An integrated receiver, charger, and PSU would be the ideal solution but I don't know if such things exist. If you can find a company like Sparkfun who sell modules they have tested together and know that works that would be second best.
 

Pongo

Senior Member
Those robotshop units looks pretty good, and there are any number of LiPO charger modules so I think it should be achievable.
 

Steve2381

Senior Member
Thanks. My main problem is size. The whole thing has to fit in a footprint of 30mm!
The smallest induction 'kit' I can find is still too big.
The battery will be a 3.7v Lipo. I am now thinking solar charging... using a very high powered light? Again.. gotta find a small solar panel.
I have already found a suitable SMD Lipo charge controller
Time to experiment
 

Steve2381

Senior Member
As a side note....

Do Picaxe as a store supply pre-programmed IC's? I have emailed their sales dept and heard nothing.
We have a different project ongoing in development that requires thousands of 08m2 in SMD format.
With that kind of quantity (our original request was for 10,000 units), I wondered if they could supply them with our code onboard.

If not, I will have to look at PIC or some other option
 

stevesmythe

Senior Member
Hello folks

Anyone attempted making an inductive charger for a Lipo? Is it even within the realm of realistic to contemplate?
If you have an electric toothbrush charger and the coil from the base of an old electric toothbrush, that might be enough to start some experimentation. Couple that with a small charge controller board and you might get there.

For solar charging, Adafruit make a kit but you can buy the bits separately from China for a quarter of the price. I bought a very similar charge controller board for about £2 and you can choose your own solar panel (6v).
 

hippy

Technical Support
Staff member
Can you not add two metallic spigots which pass through the case while maintaining its water-proof nature ?

That is how water-proof devices like walkie talkies and the like have always done it.
 

inglewoodpete

Senior Member
As a side note....

Do Picaxe as a store supply pre-programmed IC's? I have emailed their sales dept and heard nothing.
We have a different project ongoing in development that requires thousands of 08m2 in SMD format.
With that kind of quantity (our original request was for 10,000 units), I wondered if they could supply them with our code onboard.

If not, I will have to look at PIC or some other option
Yes, they certainly used to supply pre-programmed PICAXEs and I imagine they still do if the quantities are right.

Can hippy or Technical pick this up?
 

hippy

Technical Support
Staff member
Do Picaxe as a store supply pre-programmed IC's? I have emailed their sales dept and heard nothing.
I believe we do. I am not sure what the minimum order quantity or pricing is these days but our sales team would be the ones to contact.

I am not sure why the sales team have not responded to your email but it may be that it was not received. I would recommend sending another email to orders at picaxestore.com
 
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