I'm trying to build an inductive phone charging setup for < $20, wish me luck

JML

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#1
After looking at all of the different inductive charging solutions out there, I wasn't satisfied with any of them. I didn't like the price, but if any was perfect I could justify the money. The primary reason is that it's not clear to me if plugin charging is still available while using any of the inductive setups. I need this, because my wife's phone does not support wireless charging (I'd happily get her a new phone, but she doesn't want one, and that is a discussion for another thread, and probably another message board).

20180926_144237-jpg.15104

This is what I've purchased so far. The charger is this one which is currently $12.59 with the 10% off coupon on the page. I also bought some black headliner material, which seems to be 1/4" foam with a backing, and some non-slip "utility liner". That came to $3.27 with tax.
 

JML

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#2
Here are the details on the charging pad. It is made by Tesla. That is Shenzhen Tesla Wireless Device Co., Ltd. [they print it in italics]. It is the thinnest one I could find, and is very small. The cable is directly connected to the pad.


When connected to a Quick Charge 2.0 charger the pad pulls 9 volts and about 1.3 amps. Sorry for the low quality on this picture. The phone says "fast charging" and 1 hour 5 minutes until full, from about 65%.

20180926_145849-jpg.15107

When connected to a 5 volt 2 amp charger the pad pulls 5 volts, and about 1 amp. The phone does not say "fast charging", but the time to a full charge is estimated at only a few minutes longer than fast charging, at 1 hour 13 minutes.

9 volts 1.3 amps (11.7 watts) is way more power than 5 volts 1 amp (5 watts), so I'm not sure I trust the phone's estimate.
 

JML

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#3
Now I put things in the car.


Plugged into the car, the pad draws about 90% of the power it was drawing when on a proper 1 amp charger. The phone now says 1 hour 14 minutes until full. The pad does warn that a 5 volt 1 amp charger might not be adequate, in which case it will not charge continuously. If that's the case, then it will be necessary to find a way to run a USB cable from the 12-volt outlet in the forward cubby.


Here I've threaded the pad's cable through the builtin wire guide, and set it on top of the original mat. The phone will rest on the pad and the hump on the mat and charge. The door closes and seems to slightly trap the phone. A smaller phone with a thinner case might not get trapped. Of course, a smaller phone with a thinner case could use the included wired charging without any hassle.

The next step is to see if the phone stays in place while driving. If it does, then I'm done, and the non-slip material can be used under cutting boards in the kitchen. If the phone does slide around then I'll cut some of the utility liner to fit around the pad and under the phone. If that still isn't satisfactory, then I'll cut a replacement for the included rubber mat out of the headliner material.

The charging pad does NOT work when under the original mat. I'm not willing to cut up the original mat, but it does say $1.28 on the back of it, so if anybody knows where I can buy more at that price, I'd be happy to experiment.
 

JML

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#4
Took a 3 mile drive and the phone stayed in place perfectly, and added about .8% charge per minute. That seems quite acceptable to me. I just need it to keep up with drain while streaming from the phone.

Plugging the pad into a 1 amp charger the light flashes, signaling it's not getting quite enough power. Moving it to a 2 amp charger it stays on solid. In the car it also stays on solid, so I guess it's getting enough power.


I trimmed some of the headliner material to size, and then cut a hole in it for the pad. I'm terrible at arts and crafts, so anybody with even modest skill at this kind of stuff will be able to make it look better.


Everything fits perfectly. I need to get some double sided tape to secure everything.
 

JML

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#5
On a gentle drive, everything is fine, but on hard left turns the phone slides off the pad. The foam I cut to go around the pad actually makes things worse because it elevates the phone enough that it can slide over the lip and into the front cubby on hard acceleration.

My next step is to replace the entire rubber mat with a custom cut piece of foam. Then I can embed the charging pad in the foam.

What I would really like to do is 3-D print a new mat out of TPU or something, and print it with a cutout to hold the charging pad.
 

PNWmisty

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#6
After looking at all of the different inductive charging solutions out there, I wasn't satisfied with any of them. I didn't like the price, but if any was perfect I could justify the money. The primary reason is that it's not clear to me if plugin charging is still available while using any of the inductive setups. I need this, because my wife's phone does not support wireless charging (I'd happily get her a new phone, but she doesn't want one, and that is a discussion for another thread, and probably another message board).

View attachment 15104
This is what I've purchased so far. The charger is this one which is currently $12.59 with the 10% off coupon on the page. I also bought some black headliner material, which seems to be 1/4" foam with a backing, and some non-slip "utility liner". That came to $3.27 with tax.

That setup is a lot smaller than I was envisioning from the thread title!

I thought I was going to see a bunch of old extension cords reassembled into a big coil in the concrete under your parking spot!
 

JML

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#7
Hmm, yeah, I'm not sure why this was moved to the charging infrastructure forum. I guess I should have put "phone" in the title...

My current home charging setup can do 24 amps at 220 volts. The $12 inductive charger does 1 amp at 9 volts. That's a difference of something like 5270 watts. That's about 0.03 miles of charging per hour. On the other hand, I think the Tesla mobile charger can charge my phone in 0.8 seconds.
 

JML

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#8
I've given up on the home made induction phone charger, because in the course of working on it I found another solution that meets my needs just as well.

The problem was that the phone would slide off the charger. I reviewed the various printable wireless charging mats on Thingiverse, but none completely met my needs. The problem is that my phone case is thick enough that I need to have the charging pad directly against the case in order to work. The printable mats I saw all put the charging pad below the mat. My plan was to modify one of the existing mats to have a hole in it, so that the charging pad would be completely exposed.

In the course of sorting out a mat, I ran across this spacer which lifts the cable plugs 8mm, so that a phone with a thick case can be plugged in. The design also allows the plugs to be installed in the original lower position. So, I have a USB-C charging cable raised 8mm and a lightning cable at the original position, so both phones can be plugged in to charge.
 

msjulie

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#9
I'm curious how the spacer looks in the car - what I mean is, is it obvious it's there when you look down from the top?
 

JML

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#11
I'm curious how the spacer looks in the car - what I mean is, is it obvious it's there when you look down from the top?

It's essentially invisible. I printed in grey, because that's what filament was available. In black it would be impossible to see. If you look at just the right angle you can barely see it. In the picture above, you can just see a bit of the spacer between the cubby wall and the original cover. The white line on the original cover below the black phone is just glare.

Here is a reverse angle view, to see what it actually looks like installed. You can see the USB-C connector is raised up, while the iphone is using a lightning connector in the original position.

It's still kind of a pain to insert my phone, but that is because the case has a cover over the charging port. It's easy enough to do when stopped or getting in the car, but I wouldn't want to do it while driving.