The attached image shows a small table lamp I have designed and is now operational. It uses a LIPO battery with a Buck converter to power the LED. Built in to the unit is a LIPO charger with a Mini USB port for recharging the LIPO battery. The electronics are currently mounted on a Strip Board assembly inserted into the body of the lamp. The on/off switch is on the bottom of the lamp base.
I am now looking at using Wireless Charging of the battery via a charge base and have purchased via Core the DFR0362 (Dfr0362 Australia) and have a question I hope someone can help me with.
If using Wireless Charging (Magnetic Induction-MI) which side of the two coils should I put the LIPO Charger. Do I include the charger in the lamp base and power it via the DFR0362 just a straight mini USB connection to the MI coil or do I put the LIPO charger in the charge base with it feeding to the primary MI coil and then just connect the secondary MI coil in the lamp base to the battery. If I use the second approach (my preferred arrangement) what is to stop the LIPO from overcharging or indeed from even being properly charged (or maybe even charging at all) as there is I think no feed back from the LIPO to the charger so no opportunity for the charger to compensate for the change in the battery charge. At least I think that is the case but I may be way off in my thinking.
Core sell an Adafruit ADA2162(Ada2162 Australia) that purports to do exactly what I want but it seems it is for a phone so maybe the phone has the charge safeguards built in. Also this unit at $49 is quite expensive given the other electronic parts I am using and a LIPO charger is considerably less.
Hope someone can advise and perhaps identify the flaws in my thinking or make some suggestions that i can follow. I will breadboard the circuits but wanted to get opinions and ideas from all of you first.
Regards and thank you in advance
Is there a reason you need to be able to charge your lamp wirelessly?
Wireless chargers are temperamental and have quite a few drawbacks that can’t easily be worked around. Generally they tend to be very inefficient beyond a few millimetres of separation, create large amount of electromagnetic noise that can interfere with other circuits that aren’t protected from it, and can add another layer of complexity and new ways for things to break.
If you want a quick charging station without having to fiddle with plugs you could build a charging dock using Pogo pins so you just drop the lamp onto spring loaded charging terminals.
If you do want to charge your LiPo wirelessly I imagine you will need to protect the battery from absorbing stray interference from the transmitter that doesn’t come via the charger.
I think there is a bit more in it than you might realise.
You can’t just connect the charger to a coil and connect another coil to the battery. The current in the actual coils has to be AC (alternating current) otherwise it can’t possibly work. A DC transformer to my knowledge has not been invented yet. So you see there are a few more smarts behind the scenes to make these things work.
Trent is asking a very valid question here and puts up a good argument against going down this path. In other words why complicate what should be a pretty simple task. Charge a battery.
Thanks for the input Trent and Bob. Your comments make a lot of sense. My initial reason for wanting to charge the battery via a charge base was the design and manufacture of the lamp base becomes more of a problem when you have to include some sort of recess in the base to accomodate the USB connection. In the current versions there is a cutout in the side at the base (not visible in the photo) and behind that cutout is the LIPO charger’s USB port. Plug in the power and it charges. problem is we are looking at the manufacturing process of the lamp base and in some instances this will be a ceramic base. Cutoouts for the USB make other problems.
trent you are right of course the coils are AC so dumb idea from my end. Pogo pins are a good one. I hve also looked at brass contact rings in the lamp base and the charger base but that is yet another step of complexity. I do like Pogo pins however and will order some for testing.
Bob you are again correct it is only charging a battery and that is actually not a monumental task.
At least I acn put the wireless charging process to bed for a while.
Good idea. I am not sure how well these things work on phones and probably not going to bother finding out either. Probably horrendously inefficient and a disaster if you were looking at maximising efficiency like using solar.
Good luck with your enterprise
Hi Bob and @Leslie62519
I thought I should clear up a point, this wireless charging module does input and output DC but uses AC at a resonant frequency to transmit the power across the coils. The necessary smarts are included on the PCB to convert the DC to AC then back to DC again, but there are losses involved in every conversion.
Additionally, the manufacturer is claiming a theoretical efficiency of up to 90% across a 2-10mm gap, results are likely to be worse in practice so your end charger will likely only receive a fraction of the rated 5 Watt output.
I’ve done a little bit of digging and found the circuit schematic for the wireless charging module which I’ve included below.
DFR0363_Schematic.pdf (127.0 KB)
Our product page at the moment comes straight from the information the manufacturer provided us, spelling mistakes and all. I’ll make a note on our to-do list to get it reviewed and fix some of the errors on the page.
Thank you for the follow up Trent and the schematic. I think given your comments re efficiency and Bob’s wise comments i will pursue a more positive connection approach and have on order from Core some pogo pins as you suggested.
I will use those to create a connection between the lamp base and the charging base which is quite doable i just need to find or make some small brass or copper studs that can make the static connection point for the pogo pins to connect to.
The word “Module” is the key here.
I may have misread it but Leslie’s original post suggested (to me anyway) that she thought to connect her charger and the battery directly to the COILS. She may have meant complete modules which would make sense but the post did not read that way.
Our remarks about unnecessary complication still stand I think and looks as if Leslie is going to try with pogo pins which I agree would be the best way.
Usually a couple of brass screws with 2 nuts on the inside will do this job. One nut to fasten the screw tightly and the other to fasten an eyelet type connector or similar to terminate the wires.
Hi Bob, thank you for your comments and advice. Very much appreciated. Just one point 'She" is actually a 'He". I just have a name spelt in what can also be a girls name but I am a bloke I can assure you:-)
Sorry 'bout that.