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Wireless Charging
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 Posted: Sun Sep 16th, 2018 06:05 pm
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dan3192
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This is the top of the charging track. I will use IDT's color coding to identify the various wattages of Tx and Rx coils.

Next step is rearranging some locomotives for the additional pcb's and wiring, then testing and taking data.

I have 3 Watt coils for a 3rd track for 2S charging I hope to build soon. 







-Dan

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 Posted: Sun Sep 16th, 2018 11:08 pm
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bobquincy
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Switching off the power remotely is good and it is hard to beat a physical switch.  The devices used in Pololu's e-switches come close though, with Off-state leakage current that is less than the self-discharge of any rechargeable battery I know of.
Perhaps one of these devices would work for your remote switch.  I use them in my models and have seen no problems.https://www.pololu.com/product/2810  



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 Posted: Mon Sep 17th, 2018 04:43 am
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dan3192
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I'm sure the 2810 switch would work. I have their 750 power switches which I think does the same thing:  https://www.pololu.com/product/750  But with the rebuild I'll have a 1S battery management board (BMB) and Pololu's 2116 voltage regulator:  https://www.pololu.com/product/2116  plus the original DelTang Rx61x receiver.

So I'm thinking I need a SPDT switch instead of the SPST switch I was using to direct power from the Rx coil to the BMB when I'm in charge mode, or to the voltage regulator and DelTang Rx from the BMB when I'm in run mode. I have some SPDT mini switches from Miniatronics I plan to use for this. I hope this makes sense.

There's an option to control the SPDT switch with a servo that I'm thinking about, but I am running out of space. LED lighting is a higher priority.

Appreciate you making me aware of the 2810 switch.

Dan  

Last edited on Mon Sep 17th, 2018 04:47 am by dan3192

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 Posted: Mon Sep 17th, 2018 01:23 pm
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bobquincy
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I am interested in your work on this as I would like to use the idea for some of my models. Thanks for posting all the information!

For a solid state DPDT we can perhaps use a dual H-bridge chip. Pololu packages them as motor drivers, I use their #2135 but there are other versions for more voltage/more current. We may need two to get the required switching but that is still much smaller than a servo.

boB



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 Posted: Fri Sep 21st, 2018 02:11 am
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dan3192
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Being an ME, and not an EE, I'm electronically challenged. I'd like to try the 2135, but adding a motor driver adds another level of complexity I'm not sure I can handle.

One of the engines I'm adding wireless charging to is a relatively small road switcher, so not much room. I'm OK with walking over to the engine and switching from run mode to charge mode. At least I don't have to fuss with charging wires, or dirty track or removing the shell and batteries for recharging.

I think a remote on-off feature is better suited for my other, larger engine, where I'll have more room for adding such parts.

Dan   

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 Posted: Fri Sep 21st, 2018 03:37 am
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dan3192
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I've ordered these 2P3T switches to experiment with for a large diesel engine or large steam engine tender when induction charging is added. I hope to get run, charge and off-test mode capability. This should cover all engine conditions. 






Dan

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 Posted: Sun Oct 14th, 2018 01:19 am
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dan3192
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Decided to build the 3 watt charging track since I was waiting for delivery of a 1S battery protection board for my engine. I used a 1-1/4" Forstner bit to make the hole...very tricky.

Even though I went very slowly, when the bit got into the ties, pieces went flying. Fortunately the rails were not damaged and the hole looked great.

Dan
 

Last edited on Sun Oct 14th, 2018 01:24 am by dan3192

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 Posted: Sun Oct 14th, 2018 01:45 am
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dan3192
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The coil was difficult to work with. I tried to solder wires to the coil leads several times without success. I wound up using crimping pins and a pair of connectors to make a lead wire for the coil.

A rubber plug and some Kapton tape holds the coil against the bottom of the rails.

Dan




Last edited on Sun Oct 14th, 2018 01:46 am by dan3192

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 Posted: Sun Oct 14th, 2018 02:04 am
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dan3192
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The coil is about 3mm below the top of the rail. I estimate the best I'll be able to do is about 2mm from the top of the rails to a receiver coil under an engine or car. This gives approx. a 5mm gap between coils, so a lot of testing ahead to see how good a magnetic coupling can be made.

Disassembly and rebuilding of a couple of engines has started plus one or two new BPRC engines will be created fitted with charging coils and related electronics. The transmitter side electronics also has to be assembled and wired.

BTW, the white dot signifies a 3W transmitter and its location.


Dan

Last edited on Sun Oct 14th, 2018 02:04 am by dan3192

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 Posted: Sun Oct 21st, 2018 04:05 am
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dan3192
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I disassembled the drives and cleaned, lubed and reassembled them and reinstalled the battery bracket and battery. The electronics will be rearranged to include the receiver coil, receiver pcb, battery protection board and additional wiring for external battery monitoring.

If nothing else, the photo shows how one can fit a good sized battery into a narrow bodied HO road diesel (GP35) for BPRC operation.       

Dan

Last edited on Sun Oct 21st, 2018 04:08 am by dan3192

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