Two Stage Ghurd Super Controller

[wooferhound]

I have been improving my 12v Solar power system to make it capable of adding more panels to. I beefed up my fused power distribution box. I built a Diode isolated panel combiner. So now finally I have rebuilt my Ghurd Dump Controller into a SuperController. Up until now I have been using this simple dump controller pictured below.

I was in a hurry to get my system working, and used some resistors I had on-hand to make this Dump Controller. The resistors are from an old audio amplifier. This system could dump almost 6 amps. It was perfect at the time but it's not really beefy enough to handle much more power than I am making now. Ghurd hooked me up with some real resistors and another Controller so I could make the GhurdSuperController.

This is my new 2 stage Dump controller already installed. It has 2 seporate Ghurd Controller Modules in it. The first stage can be set to start dumping at 14.5 volts, while the second stage can be set higher to start dumping at 14.7 volts. This makes it easier on the battery as large dump loads are not used until there is a large amount of power to dump. The resistors are hanging on 3/8inch threaded rod with little heatsinks made from big fender washers. The threaded rod is bolted tightly to the chassis which makes an it into an even bigger heatsink. The top row of resistors is Stage 1 and the 2nd and 3rd rows are Stage 2. The 12volt fan only operates when any of the 2 stages are dumping. The fan gets it's power through 2 isolation diodes that charge the Big Blue 10000mfd capacitor on the lower right.

I also made each dump stage adjustable with switches. Stage 1 can be set to dump at 3 or 6 amps, while stage 2 is settable to 6 or 12 amps dump. At this time I have everything set to minimum since I only have 3amps coming in right now, but I can really grow into some more Solar Panels and other RE inputs easily. I included On/Off switches on each stage too. This will let me operate the unit on either stage independently or turn them both off for Battery Equalization. The dump indicator LEDs are here also, plus there are LED outputs on the terminal strips for some dump indicators inside where I'm using the power at.

Here is "DanCADD" schematic diagram. It's hard to read but it's all correct. Except there are reverse Freewheeling diodes on each resistor bank to cancel out the possible Back voltage the coils in the resistors might create when being switched off.

- Results -

 This has worked perfectly since the moment I installed it and switched it on. Of course I had to do some minor tweaking to get the 2 stages dumping at the correct voltages, but all the functions work just fine. When I switch between High & Low amp dump settings, the LED flashrate does not change, but the On-Duration changes. The cooling fan (.14 amp) will run usably for about 5 seconds after each dump pulse and the whole thing runs cool enough to touch, even directly touching the resistors that are continuously dumping. As I add more power inputs I will need to watch and see how hot it gets. it's max dumping ability is about 300 watts at 18 amps.

This Dump controller was built inside the metal cover for a thin-form UPS unit that had been toasted. You may notice in the second picture above that this controller is mounted next to my Diode Isolated Combiner unit built in the golden metal. That was the Inner Chassis of the same UPS unit.

About the time I got my controller setup properly, it has started clouding up early every morning, and threatening storms in the afternoons so I haven't had the fun joy of sitting here watching my dump lights flashing, which is much more fun that watching the panels themselfs.

Here is a link to my system in Oct. 2007, it has been much improved since then.

http://www.fieldlines.com/story/2008/3/4/6303/63451

Here is a link to Ghurds Dump Load Controller, I highly recommend it.

http://ghurd.info/


W o o f -={(

[Dave B]

Very nice Woof. I don't quite follow the fan operation. Is this just run intermittently off the charged cap some how when ever both loads are on ? Great job and well worth the effort I'm sure.  Dave B.

[wooferhound]

Sure ,  I'll explain the Fan operation a little better . . .

If any one of the 2 stages pulses a dump voltage to the resistors, it also pulses the capacitor through an isolation diode, which charges up the 10000mfd capacitor and can keep the fan running for about 5 or 8 seconds. The the diode isolates the capacitor from the resistors preventing the capacitor from discharging back through the resistors. The ghurd dump controller can be set for a wide histersis range and I have mine set for .01 volt. Set that way the controller can pulse dumps quite rapidly. It is rare to see it pulsing dumps more than 1 second apart. I usually see the dump pulses running faster than 10 times a second, but it can easy be so fast that the dump light appears to stay on continuously.

There has been some discussion about how bad it is to charge a capacitor Hard like this in the first few dump pulses that may be more than 5 seconds apart, but I have never heard of any actual problems doing this, plus this is a fairly high quality cap.

[GeeMac]

Gadzooks!!

[valterra]

I just wanted to chime in here about that controller.

The heart of Woof's design is that GHurd controller, which is the simplest, most straight-forward piece of circuitry I've ever put together.   And it is the only part of my system that "just works" no matter what.

There are really pricey controllers out there - and there are junk ones like my deceased Harbor Freight charge controller.  This one is cheap and easy.

Make a simple one to save your batteries.

Make 2 of them like woof and a complicated (and cool) 2-stage system.

But just make one.  Your batteries will thank you, and you won't have to babysit your system anymore.  Like Ron Poppeil says, "Set it!  And Forget it!"

[Opera House]

It wouldn't hurt to put a few ohm resitor in the charge part of that cap.  A greater concern than damaging the cap is damaging a FET.  A really good large value cap would look like a dead short and stress a FET that was operating close to its limit.  I have used this method with higher frequency PWM dump and it is an easy way to turn on the fan as resistors start to get toasty.  In faster PWM circuits, use a fast recovery diode otherwise it will be conducting in both directions.

[ghurd]

Wow!

That may be the most complex use of the circuit so far!

Nice to see people can run with it,

G-

[Bruce S]

Just goes to show... "it's the little things that count :-/

Cheers

Bruce S

[wooferhound]

We had a huge lightning storm last week and I seem to remember 10 or more strikes where the thunder was simultaneous with the flash. The power went off a couple of times interrupting a movie we were watching. Everything seemed normal that night, but the next day the batteries just were not charging right. The next day I changed to a backup battery and it went to 9 volts in the next 24 hours and a grid powered charger was not helping.


I went out to the battery shed and started measuring stuff. I touched one of the resistors on the dump controller and it was warm and so were several others. I pulled the fuses for the dump system and focused my attention on the dumping system.

I got some tools and a better meter and plugged the fuses back in. It seems that a couple of FETs were blown and were Locked On. The next day I tested if the Ghurd Controllers were working. It appears that one of them is blown and the other one is working but had a blown LED dump indicator. Fortunately I have a spare Ghurd controller along with it's Spare FETs, Now if I can only find the time to fix it up proper ,   maybe tomorrow?

[Rover]

Only you would have a spare "Ghurd Controller" ...

With the damge that the system looks like it took, I figure eh.. not so bad .... (kidding) .

Waiting for the day I can buy Ghurd stock ....

[wooferhound]

The picture I added is from the Construction, most of the stuff isn't hooked up on there.
I have become the Human Charge Controller ,  That's how TomW would describe it.
Now I have a new problem . . . I don't have a spare Ghurd Controller anymore . . .

[Boss]

Only you would have a spare "Ghurd Controller" ...

Not the only one
However Woof does have a very nice power dissipation bank I wish I had built something like that

[hydrosun]

I've used C-40 controllers to turn on heaters for dump loads for years. Most had brushless fans on the same circuit and turned on at partial speed to match the amount of heat created by the resitance wire. I've had very few fan failures. The only one that caused problems was a fan with plastic parts that partially melted because it was too close to the heating elements when the fan stopped working. The replacement fan was mounted a few more inches away to keep it cooler if it failed. So with the pulsed output of the controller the fans worked fine in most instance.

 I didn't need to set up any separate circuit to turn on the fan. I can see where the capacitor would help smooth out the pulses but I've found it works fine without.
 
On my own system I have six voltage controlled switches to turn on loads at ascending voltage points. From the hot water tank, floor heater,heater by the computer desk, plug in the kitchen for tea kettle,  to two split heat pumps. Controllers are two Chris Greacan home built, a solar converters simple switch, MX-60 aux switch, FX-2024 aux, and Tristar 40 amp. So I've tried many ways to direct surplus power. 
The Ghurd controllers seem to be very robust and I'll be looking at using them in the future.
Chris

[wooferhound]

- Update - Do Not Panic - My System Will Survive - Alert - All is Not Lost - Dump Controller Lives - Thanks Ghurd - Power to the Electrons - Do Not Be Alarmed - This Is Only A Test - PING Timeout - Error Loading Paper - Buffer Overflow -


I worked on my Dump Load Controller today and discovered that both Ghurd Dump Control modules and 2 of the 4 FETs were blown up by the lightning strikes last week. I replaced both FETS and one of the Ghurd Dump Control modules. The system is working fine on a single stage of Dump Control right now.

My spare Ghurd controller was still in the form of a Kit and I sat down in the living room and assembled it as my wife restrained from complaining. I took the newly made module out to the shed and carefully replaced the Stage 2 module in the chassis. Then I plugged the Dump Fuses back in and the Indicator LED came right on. Adjusting it with a small screw driver, I quickly found the set point and got it all set correctly in about 10 minutes.

This will work for now but I need to order a few more parts from ghurd to bring it all back 100% and have spare parts onhand too.


Here is a picture of the general layout where my Solar Panels are. The panels are on the shed and on the ground. Then there is a major utility pole on the property line. I'm betting that one ore more lightning strikes hit the Ground Wire at the top -then somehow- flashed over to my shed and solar panels and eating some electronics but not actually burning anything up.

All the panels and all the combiner diodes are still testing out good