Category: Hardware Hacking

VFD Update, Stripped the AC front end.

I removed the input AC components today. The drive had a lot of weight in components just to drive a 110V fan. I’ll obviously have to replace that AC fan with a DC fan. It won’t have the CFM output of the original but I won’t be generating the heat it had. This monster was in a building right next to I-405… you can tell is was breathing a lot of fallout it’s whole life. It’s amazing where the dirt and scum has found to hide and how much there is.

I was happy to see the only thing the AC provided power to was the cooling fan and then straight to rectifiers… that’s great news of course.

I know it was wishful thinking but I threw 160 VDC at it… didn’t even blink. I’m just going to have to wait until I can get my hands on more batteries. My 20Ah batteries are looking like they’re going to be garbage… they’re just too far gone I guess. All the recycling tricks are proving to be crap 🙂

Check out that toroid!
Check out that toroid!

Edit: that board up front is the variable voltage rectifier controller… It is also going to be removed

Sometimes you get what you pay for! An attempt to bring back SLA batteries

If you’re reading this, perhaps you’ve run across the endless forums of magic battery revival modules, advice for adding acid, water, salts.. whatever? I spent a solid day reading/surfing.. maybe there are a few magic ways to save your batteries? I don’t know lets see… but before I start let me say one thing: Have a ten year old car battery you’re trying to make last another two? Well, sit down, this may sting… you’re cheap.. buy a new damn battery! 🙂 I scored four *free* 12V 20Ah SLA batteries.. they were installed 2 years ago.. only lasted in some biomed equipment for about 18 months… why? Who knows.. they aren’t used much.. probably a crappy charging system in a 20,000$ piece of equipment. Worse case I drive a mile down the road to drop off the batteries for recycling (also free).

I refuse to chuck these.. even though they are really in a bad way. Status of batteries: 4-6 Volts… DEAD. Below dead.. and they’ve been sitting that way for weeks. So lets see how these goes! All batteries are close to the same age, came out of the same equipment and are roughly the same voltage. Also of note, these aren’t gel cells.

Battery 1: I put battery 1 on a Powersonic SLA battery charger (12V 4A..) PSC-124000A for 24 hours. the battery charger sat in float the whole time.. didn’t get warm.. didn’t draw much more than 10mA — not looking great.

Battery 2. This battery went through the same 24 hour ineffective charge as above…. I popped off the top. The cells were lacking water, I don’t know what is normal but it looked considerably low. I put about 150mL of water into the six cells which brought it up to just under the vent ports. I also put in two drops of sulfuric acid into each cell (why not!?). I threw it on my current limited power supply 15VDC and I put the current trip at 250mA just in case something gets away while I don’t have my eyes on it. I’ll adjust this later on if needed. It started off at 10mA, but I’m in about 4 hours and i’m up to 50mA… lets see what a day or two does?! Many of these sites mention this process taking a week or two. I’ll put the battery on the powersonic charger once my current gets up to 100mA or so.

Battery 3 & 4… To be continued!

 

Weekend stepper fun!

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I got got home to take delivery of this front end frame piece. Now I’ll be busy this weekend working on electronic steering. The PIC 16F1509 will be controlling all steering functions. I’ve written a remarkable amount of code for how long it’s been since I worked I a project with a F628A and 18F1330 motor control for the Roomba sumo bot. This project has gotten painfully expensive despite scoring some nice freebies. I spent way too much on wire because I want MTW or Teflon.

Doubts about the IGBT isolated drive voltage

Fresh out of repair I hooked up my IGBT pack for testing one channel. I had vaporized some traces off the secondary supply voltage. I hooked up the load, the low voltage drive and then my best guess on the isolated power supply. I guessed wrong. I was hoping because the Chiller had a good 4 or 5 24VAC secondary transformers and 24VAC is ubiquitous throughout the HVAC world. I guessed wrong. I let some more smoke out.

I am lucky I have a new friend who works on Chillers. He hooked me up with the water-cooled heat sink and I have a pump and some capacitors coming to me as well. I’m going to ask him to let me poke into an operating board with my multimeter next time we are working together to find out whats going on. The pair of wires is feeding 6 isolation transformers in parallel with what I thought were MOVs but it’s hard to tell, no markings and I doubt my soldering skills could get them safely off and back on again? Maybe…

Well back to the drawing board… rumor has it they might have another (smaller) drive out of a refurbished unit…. could I be so lucky?

IGBT pack married to it's heat sink
IGBT pack married to it’s heat sink

Lithium Battery Boost Power Supply Comparison

I purchased two boost converters or DC to DC power supplies, or whatever else people want to call them on eBay. One was a LiPower board from Sparkfun for $14.95. I assume it’s made in the US, has a battery connector and can be soldered with 0.1in pitch terminals. It’s setup for low voltage drop out at 2.6V but there is a small hack to reduce that (though I feel like you have better options if you’re trying two NiMH batteries because it has reduced current abilities from the hack.) See the sparkfun site for more details, including the link to the hardware hack. The output is a small solder jumper that comes preset to 5V but wouldn’t take but a minute to convert to 3.3V.  https://www.sparkfun.com/products/10255

I put a small load (my anticipated load of a project) of 50mA and this device measured at 85.3% efficient.

The other device I bought was a cheap-o Chinese converter that came as a two-pack from Hong Kong. It came with a USB connector and took anything 2 to 5V. I tested this with a 2.4V battery pack and it seems to cut out at just under 2V. The efficiency was measured at 77.0%… Also with a 50mA load. My input voltage was a bench power supply set to 3.7V to simulate a LiPo battery on both tests. A nicety of the Chinese “mobile booster” board was the red LED showing output power status. The LED blinks rapidly when it goes into low voltage cutout. The cheap-o board also output 5.20v which was fine for my application. I think I gave roughly $4 both boards with free shipping.

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IGBT Pack and Drive Pin Diagram

So if anyone runs into an IGBT pack from a York Chiller I’ll do you a solid and give you a pin diagram.

York part number: 031-02061-001

The connector is of this style (p/n from package, I forget which side): 1-794223-0 http://www.digikey.com P/N: A100435CT-ND .. using this you can find both pieces.

.. all TTL is 5V the “/” is a low level input designator. PIN

1: U1 (5VDC)

2: U1+U2 /FAULT

3: U4

4: U5

5: U5+U6 /FAULT

6. T1 (RTD 5K)

7. DC NEG

8. Vcc (5VDC)

9. Isolated Power (I think this is 24VAC but I’m not sure)

10. U2

11. U3

12. U3+U4 /FAULT

13. U6

14. /RESET

15. T2 (RTD)

16. N/C

17. DC NEG

18. Other side of isolated input I believe.. I blew mine up before I could fully test this.

… as for the IGBT it’s 2, 4, 6 are + (up to 1.2kV) and 1, 3, 5 are the negative side, the others are the 3 phase output. New, this pack is painfully expensive.. $1,400 but maybe you’ll run into a good deal or some “garbage” as I did. Good luck!

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