Just a short video testing out the newly mounted slip ring. No power is being routed yet, but I wanted to see how it worked in place and if there was any pulling on the cable.

I really am building honest and Artoo is back on the workbench.

I’ve revised my battery charging system and in the process of making a new harness for the larger batteries. I’m also reworking my fuse system, so basically everything had to come out. This may look like a mess, but I know where everything goes back honest!

The new battery harness is designed it in such a way that I can mix my old 7ah batteries  and the newer 18ah. I added a little arm that folds out and holds the smaller battery when needed.

Here it is with mixed 18ah and 7ah batteries in place

Arm out of the way and two 18ah batteries this time

Tonite I’m hoping to finish up the re-wiring.

I cut the hole for the slip ring tonight.

Started off by marking the center lines and then using a hole cutter to score the 7/8″ outline where the slip ring body would sit.

I then marked off and drilled holes where the slot would go for the cable plug to pass through

I used a Dremel and a hand saw to join the holes up

You can still just see the outline of the circle I’d marked

I then took a file and made the small circle notches either side of the slot to accommodate the slip ring

Testing that ring slip ring fit and that the plug will pass through

Top view of the slip ring secured in place

Now to solder up the connectors

I started work on my test slip ring tonight and hope to get it installed in the next few days and report back on a new group order.

The sample slip ring has eighteen 2A circuits and I plan on grouping together 6 or 8 for the +/- 12VDC uplink to the dome, leaving ten circuits for PWM/servo signals. To save on circuits I’m not planning on routing the +/- 5VDC from each of the PWM pairs through the slip ring. As a result each RC channel will require just one wire allocated on the slip ring. I’ll just tap of the 12VDC in the dome and re-create a separate 5VDC supply for the servos.

Out of the box the slip ring wires are loose and really needed protecting.

I bought some braided expandable nylon wire wrap from a local surplus electronics store for less than a dollar.

I wrapped the ends in electrical tape to hold things in place.

Now that I have the wire wrap in place I can start soldering the wires to the connectors.

Here’s an overview video on how I plan to implement the wiring

A slip ring, in electrical engineering terms, is a method of making an electrical connection through a rotating assembly.

In our case it could be used to route power and other signals into the dome, but still allow it to rotate continuously without tangling wires.

I’ve been toying with the idea of putting a slip ring in my droid for a couple of reason

• Remove the needs for extra batteries in the dome and save weight at the same time
• Easier charging of the batteries
• I’m upgrading my RC setup to 2.4Ghz in the next month, and this would allow me to eliminate an expensive second receiver in the dome.

Here’s a quick picture of a sample I picked up today.

It’s pretty small, but offers 18 circuits, each capable of 2A. The company that sells them is close to where I work and they also sell a much smaller 6 circuit design as well as 12 and 24 in the same size package as above.

I plan on testing it out in the next couple of weeks and will report back on my findings.

I can’t believe it’s been a month since WonderCon — I’ve done very little on Artoo since, which as been a nice break, but I feel guilty that I still need to go back and post on work I’d done last month.

The good news is, as a result of us being at WonderCon there’s at least one new builder who’s jumped head first into building. What’s even better he only lives a few miles away from me – Welcome to the club Steve!

Today I did get together with Gerard to talk droid and strip my Artoo back down ready to implement my revised battery system. I was hoping to get a few more local builders over, but being easter it was hard to arrange at such short notice.

The easter bunny also brought me newer bigger batteries. I’m going to replace the smaller 7Ah batteries with a single 12V 18Ah battery. Thanks Gerard!

Now to try and get the battery to fit and still be easily removed.

I’m probably going to position the new battery just off-center with a second smaller standby battery for the RoboteQ to the right. Based on the height of the battery and the clearance needed to get it in and out, the new holder/harness will probably much shorter than my original.

I’m also even more convinced that I should loose the fuse block, which works well and even has a battery voltage read-out, but it’s somewhat overkill and gets in the way of battery removal. I could try putting it deeper into the droid, but that then defeats the purpose of keeping for the voltage display.

In closing here’s shot of my frame minus the skins

Update 4/21/08: Click here for the latest wiring schematic.

Here’s another revised version of my 12V battery and charging system. I’m now using additional relays to isolate two sets of batteries which can be charged independently.

I’ve also added a little bit more detail to the schematic to show additional connected sub-systems.

There’s also a PDF version available for you to download and print.

Related Posts:

• Updated Charging Circuit

Here’s a couple of shots of my “finished” charging port and bracket and the associated wiring and electronics before I mounted it. I say “finished”, because I’m currently redesigning the circuit again to accommodate for charging two sets of batteries to work around the RoboteQ problem I experienced at WonderCon.

I ended up soldering the LED array to a small board. They were okay as standalone strings, but mounting them permanently to the bracket was easier this way. The ribbon cable on the left runs to the PICAXE board, and I braced it to make sure the wires wouldn’t pull out

Here it is installed in back of the port bracket

I added a length of acrylic to the original aluminum bracket to mount the additional electronics on it

Here’s the PICAXE board mounted. It drives the LED array

Almost done. I wired in the relay and switch that runs to the main fuse block and batteries.

The relay is hard to see, but click on the image to see the large image and the relay is on the top right of the photo

Related Posts:

• Battery Power Issues Resolved
• Charging Jack LEDs
• Updated Charging Circuit
• Relays for Charging System