Its now about 1:30 in the morning, so this post might be too late for the contest. But I finally finished my wireless charged snow groomer. After doing the final reworks and bodges on the PCB, I added the needed connectors and put everything together.
Receiver
For the wireless receiver, I added a small support board that holds the receiver PCB with the coil attached to it. I put the coil on the back side of the receiver PCB, and fixed it with two layers of Test Power Strips. That helped in leveling out the solder joints from the PCB:
I then mounted that PCB on an acrylic plate, and used standoffs and spacers to get it to the right height.
PCB reworks
Nearly all parts of my circuit needed some form of touching and reworks. What once was a nice board now looks quite patchy:
(Top side, with most of the reworks for the end-of-charge circuit)
(Backside, where the wires are for the differential amplifier)
On the right side on the back one can see the PCB areas designated as heat sinks for the balancer FETs.
Connector puzzle
After finishing the PCB (and verifying that everything works as it should) I added connectors to put everything together:
Here the base plate is visible. It also holds the PCB, which gets half-hidden under the receiver board. To allow that, I removed the test points and the programming header from the receiver.
The battery is a 11.1V, 1300mAh race car battery (an extron X1), which comes with both a balancer connector (for charging) and power leads. I added a screw terminal to them, so I can remove it easily.
The final step
As final step I just needed to fit everything in the battery compartment of the snow groomer. Since I measured quite carefully, I knew how large all the stuff was allowed to be. So it was not a surprise that everything did fit in snugly:
The battery and the acrylic plate span together the whole length, to they hold quite tight. On the side there is enough room for the connectors. It was a welcome surprise, after all these set-backs in the last few days, that it did indeed work on the first try.
When putting it on the charger base station, I found out that it fit a little bit too tight - I should have save some millimeters there... But the charging notification on the transmitter turned on, and also my current sense notification. Even though its a little bit hidden:
I also should put the USB power cable entry not to the side, but to the front, since its now to close to the driving chain.
But the status LEDs from the transmitter a visible, so I consider this as OK.
Wrapup
Thanks to Element14, Texas Instruments and especially Würth for this contest, all the parts and the support given to all the contestants! Many thanks especially to Christian and Simon!
Even though it has been stressful at some times, this was a fun project. My son was delighted when he discovered (today in the afternoon...) what I did build for him. And for me it means there are now two toys less where the batteries are empty at the wrong moment, and I don't need to keep charge of them. I also learned a great deal, not only about wireless charging.
This won't be my last post on this project. I still need to come up with the final schematic. And I also will need to do some more verifications and tests before I hand this project over to my son. So I will report about that also, but give me a short break to catch up with my sleep...
All the blog posts
In chronological order (more or less):
Beyond the phone - ein Plan muss her!
Wireless power demo board - Ein erster Eindruck
Wer misst, misst Mist - or measuring the performance of the wireless demo kit
Besser zweimal messen - update to my performance evaluations
Wireless Power - Pläne schmieden
Wireless power - Wie lade ich einen Akku-Pack?
Wireless power - charging a battery pack part 2
Wireless power - charging a battery pack part 3
Two times is not enough - Measuring the performance of the wireless power demo kit part 3
Wireless power - battery undervoltage lockout with multiple cells
Wireless charging - status update
Wireless charging - complete schematic walkthrough
Wireless charging - status update 2
Wireless charging - status update 3
Wireless charging - proof of work
Wow, 16 articles. Thats nearly one article per week. I did not remember to write that much...
