Modding an Apple Mac Pro Power Supply

 I got an old Mac Pro power supply to replace my puny old Dell.  The thing is massive!  79A of 12V power, that's over 900 watts!!

But, there's a catch.  Like all things Apple, it's a beautifully crafted, high quality unit.  And unlike the rats-nest wiring associated with PC power supplies, it's got a single clean wiring harness which is sadly undocumented on the Internet.

 I guessed the large connectors would be for 12V and ground.  Measuring the voltages would indicate the polarity.  BUT  How to turn the unit on?  I was looking for the equivalent of the PC's Green PWR Wire, the one that if shorted out turns on the power supply.

Going strictly by guess, I started shorting out pairs of connections.  I figured it couldn't do much harm, since none of the wires would be carrying current if the PWR wire were not engaged.

Using a paper clip, I quickly found the pair of PWR,GND connection.  I'm not sure which one is which, but for my purposes it doesn't really matter.  I made a note of the connections so that I'll be able to recreate them when I cons up a connector to the charger.

The outside big connectors are both GND, and the inside big connectors are both +12.2V.  The PWR/GND pair is the outside small connectors, second from the bottom.  The connector is oriented so the left side is smooth, and the right side has the edge.

A slight bit of fiddling showed that the small curve of a paper clip was the perfect size to connect PWR/GND.  I snapped a picture of it and will cover it with tape to ensure it stays put.

That's it for the experiment phase.  I'll use the flat blades from an old extension cord to bodge up a connector for 4mm bullets which is what my power supply uses.  I'll update when I do that!

Note: I think it's this model:  Apple 661-5011 980 WATTS POWER SUPPLY


Here's a video walkthrough:

blogodex = {"toc" : "Power Supplies", "idx" : ["Mac", "charging", "power", "electronics"]};

Next Gen 1S Super Charger Coming Up!

epilot@rcgroups notes a new lipo charging solution over at banggood. 10 pieces for less than $10!  I'm going to get a batch and try two things:

• Next Gen Super Charger, even lighter weight than the old one.
• Embedded Lipo Charging for the ArrMote.

notes:

• resistor R3 determines the charge current.
• 1.2Kohm on board, meaning the charge current is 1000mA.
• Substitute R3 as per the Rprog table in the data sheet to reduce charge, e.g. 5Kohm = 250mA charge current.
• lowest charge rate = 130 mAh
• boards have an overcharge protection circuit.

Here's the TP4056 Data Sheet and the current table.

RPROG (k) IBAT (mA) 
10         130 
 5         250 
 4         300 
 3         400 
 2         580 
 1.66      690 
 1.5       780 
 1.33      900 
 1.2      1000

blogodex = {"toc" : "Charging", "idx" : ["Super Charger", "1S Charger"]};

New Battery Bunker

 Here's my new battery charging bunker.  It's a concrete block, with flats on top and bottom.  I chiseled out a slot for the wiring.  I'm going to try the "sand in bag" technique for the top.  The idea is that you put the sand in a plastic bag, and a fire will melt the plastic, smothering the battery.  I might keep the concrete flat on top of the bag, so it will totally seal.  There's a smoke detector on top.

Here's the reason for the new battery bunker.  It was a 3S 500, relatively small.  I'm pretty paranoid about watching over charging, so I was there when one of the cells popped.  I took it off the charger and examined it; within a couple of minutes smoke started coming out, so I tossed it out the door and it burst into flames a few seconds later.  I wasn't concerned with the leaves, because it was a rainy night and everything was soaked.  I've also got a fire extinguisher next to my bench; you should too!

Update: with the recent dry weather, I have a sand-filled bucket sitting outside the door.

blogodex = {"toc" : "Battery Safety", "idx" : ["Batteries", "Charging", "Safety", "Battery Bunker"]};

12-battery 1S SuperCharger Completed

Part 1 here.

The remainder of the parts came in, so I soldered up the connectors and elegantly hot glued everything together.  I've been using it for the last couple of weeks, and it's been great!

The Turnigy FC100 micro-heli chargers are the cheapest... at $2, they're less than half the price of the other flavors.

If you're getting connectors for a Walkera, be careful because there are apparently some other vendors that use the opposite polarity of Walkera.

Here's the charge leads soldered onto the tabs.

Totally now I've got 12 charging ports... four each of Eflight, Turnigy FP100, and Walkera.  There's still an open USB port as well!

Note: if you do this, be sure and check the power adapter provides sufficient amperage so that each charging unit can draw 500 mA.

Super-Duper 12-cell, 3-format 1S Charger

I've really loved my Eflight 4-port Celectra charger.  It's portable and does a great job charging Eflight-style 1S batteries.   But, I have a new love now... When I bought both my Ladybird and my HK FP100, they both came with a tiny 2-port charger powered off of USB.  This makes sense, since USB will deliver a 500mA 5V current, just right for charging two 1S cells.  I wanted to do the same for the eflight-style batteries.

So, I ordered an extra FP100 charger (less than $3!) and soldered in some eflight charging leads.  It was easier than I thought.  I didn't need to unsolder the FP100 connector from the board; instead they were perfectly sized and positioned to be solder pads for the cables. I did open the case to do the soldering though, so I wouldn't have to be so precise in navigating the soldering iron in the plastic case.

After soldering I put the case back together.  Line up the tabs on the FP100 connector or you will bend the heck out of them.  You could do the same thing with the Walkera charger, but those run about $8 Stateside, and HK is perpetually out of stock.  If I can find some Walkera leads (with the right polarity!!) I might make a version for them using the FP100 charger.

Here's the final goal: a 12-battery 1S supercharger, capable of handling four each of three different styles of connectors: eflight, walkera, and HobbyKing FP100.

I've hot glued the chargers to an old USB hub, and will power the hub from a wall wart power supply.  I think I'll be able to fit six of the chargers onto this particular model.  I wish I could find some 3 inch cables!  If I were to go totally insane on this project, I would eliminate the connectors and directly solder the power leads.

  I'll check the amp rating on the hub and power supply to see if it will charge 12 batteries simultaneously at full power;  It would be cool if it did, but I imagine I won't be needing to do that very often.

Open Source Lipo Charger

Very Nifty! Paul Asselin has an open source hardware design, based on the Microchip MCP73831.  You can download the schematics and Eagle files directly. He also sells a kit or completed unit.

A Handy Sticker for my Charger

Here's a handy sticker showing all the important charge values for 1-4 cells: low (absolute and recommended), nominal, and high.  I should add a row for LiFeP04 batteries.

An Idea for a Safe Lipo Charger

I heard somebody describing this idea, but I can't remember who.  He had seen a much larger system like this while working on a military project.

• take two flowerpots.  flowerpot 1 is the base, flowerpot 2 is the top.
• cut a notch out out of the rim of flowerpot 1.  this is for lipo charging wires.
• fill flowerpot 2 with sand.
• cover flowerpot 2 with a sheet of thin plastic, something like grocery bags.
• secure the plastic around the rim.
• attach a piece of chickenwire to flowerpot 2.
• put the batteries in flowerpot 1.
• place flowerpot 2 upside down over flowerpot 1.
• if the batteries catch fire, the plastic will burn and the sand will flood the batteries in flowerpot 1.

This works best if you have nice long charging cables.  I intend to try this some day, but for now I'm just using a lipo sack since I usually am charging small batteries one or two at a time.

It would be nice to have this setup sitting on the porch and just run the charging cables outside.

e-Station charging software and driver

e-STATION Chargers for Electric R/C:

This is for all rebrands as well, including the THUNDER AC6.

To install:

• don't attach USB yet!
• download and unzip
• run setup/setup.exe
• click "install driver".  this will install a driver for "Silicon Laboratories CP210x VCP, CP2010x USB to UART bridge".
• click "install monitor"
• serial number is in SerialNumber.txt
• reboot 
• attach USB
• run all programs/estation/estation

If anybody knows of a mac version of this software please let me know!

I'm installing it in an XP vmware fusion session.