Hi all,
Can anyone shed some light on using DFROBOT FIT0703 wireless charging module 12V/3A to charge a lithium battery.
What size battery is module capable of charging? I need to charge a 12-15AHr battery.
I have a 24VDC power supply on input module, should i use a dc-dc charger on output module?
Has anyone had any success with this.
Thanks Frank
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Hi Frank,
Could you share some specs on your lithium battery? Maybe a photo? That’ll give us some pointers as to what extra hardware you’ll need.
Generally, batteries with Li-ion chemistry need special chargers, not just a DC voltage applied. More info here:
-James
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Hi James,
Thanks for for reply and very informative video.
I am wanting to charge a 12.5Ah battery with CC/CV charging mode (photo attached).
Some larger systems may require a larger battery say 25Ah.
At the moment I have setup on test bench:
24VDC 5Amp regulated power supply supplying input board of DFROBOT FIT0703 wireless charging module. I have confirmed 12V output is present.
On the output board I have tried different setups:
- Connect straight to battery, this setup powers up equipment but didn’t charge (wishful thinking but I new it wouldn’t work).
- 12 volt output into solar charge controller PWM and MPPT types, both types are capable of charging lithium batteries. (I was hoping voltage from wireless module 12V output would be enough to initiate a charge from solar charge controller, again wishful thinking).
- I haven’t tried a DC-DC charger yet.
Clutching at straws here, your help is appreciated.
Thanks
Frank
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Hi Frank.
Maybe you should read the notice on the battery.
12V is not enough.
It clearly states the charging voltage should be 14.6V.
Cheers Bob
PS. The charging smarts could be built into the battery. Check with Jaycar or Electus Distribution.
EDIT. The 14.6V charging voltage must be limited to 5A or below for this battery as on label.
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Hi Robert,
Thanks for your reply.
Yes I realize this hence the solar charge controller which has an input voltage range of 8-32V.
I has hoping to trick solar charge controller with 12V from wireless charging module but they must sense that solar panels aren’t connected.
Would a Lithium DC-DC charger work? DC-DC charger takes 12V input and charges battery on output.
Frank
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Hi Frank,
Excellent discussion so far by the way!
Another point worth mentioning is efficiency and the circuit you’ll need to get this working safely.
Efficiency
In charging such a large battery there will be a large energy transfer, the wireless module quotes up to 95% efficiency, assuming that is true for up to 36W output you’d need a ~38W input (~1.6A) the 2W might not seem like much but it will definitely add up as you charge the battery.
Safety
It mentions that the receiving module should not be back-fed, the solar controller might handle that though a solar panel is a large diode, to be doubly sure it would be best to include a low forward voltage diode on the receiver.
An unlikely but possible failure mode could be that the some component in the receiver module fails and the full 12.8V 12A is passed through it (very very bad).
Just curious what the application is that requires the wireless module to be used?
Liam
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Hi Liam,
Thanks for your reply, we manufacture Inclined Lifts driven by a winch cable setup. There is no wired connection between control panel/PLC and lift, (ie lift electronics communicate wireless with control panel/PLC). Battery sits in lift powering electronics, when lift docks at a nominated station/landing we require the battery to charge. At the moment we are using a battery charging contact setup where contacts on the lift come in contact with contacts on the beam the lift runs on and charges battery while stationary at station.
Looking to improve setup using wireless charging setup instead of contacts.
We found this wireless charging module at Core Electronics shop and thought it might be a start in developing this new setup.
Open to any other suggestions.
Thanks
Frank
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Hi Frank,
I’ll preface this with I’m not a qualified engineer.
I fully understand where you’re coming from in wanting to get wireless power to charge the batteries but it might open up some less favorable areas.
I think the best option would be to keep things simple and expand on the use of contacts.
A few reasons, replacing/testing, with a contactor all you’d have to test for is continuity, whereas to debug the wireless charger it could range from a multimeter to an oscilloscope.
Reliability The magnetic field strength will fall off with the function 1/distance^2, so if its a bit further away you wont get the full charging power - other nearby metal objects will also get hot and create inefficiencies.
@Liam makes some other good points regarding why it might not be suitable though if everything still seems in scope it would definitely be worth continuing down the path.
It seems promising, you might have to do some filtering though.
I’m keen to see how you go!
