1st ghurd controller built...

[Madscientist267]

Well, I finally got around to putting together the first of 3 that I ordered, and it went together without a hitch, with the exception of a minor inconsistency from the pics on the site and the parts listing.

But, I followed what I read and put in an 8.2K (as documented) instead of the 51K (as pictured) for R5, and she works like a champ.

Being the first one, I didn't quite follow the directions exactly, and made a couple of mods for giggles, but it will work just fine anyway, considering the maximum dump requirements are for an 8W solar panel.

First, rather than running the MOSFET source/drain leads directly to the battery, I just handled things with a little heavier wire and ran the MOSFET and dump resistor across the input. This would be a problem at higher power levels, but for this, it doesn't seem to matter. It holds regulation very well.

Second, rather than using the yellow LED for the dump indicator, I put a small piezo buzzer (with built in oscillator) across the dump LED output, and shunted the dropping resistor. The buzzer can be cut off by a push-on/off switch for those times when 'ok I get it already' comes to mind.

And third, I will be using a flashing LED (in place of the green) to indicate that the unit is indeed receiving power and 'should' be functioning as expected. This was due to the ~5mA draw that the green LED had drawing full time. At this scale, that can add up. Good call tho G, 3.3K is an excellent choice to minimize parasitic draw!

The idea is to test this very small system as a small scale 'what can I get from this' level, and see how she goes. When there's surplus power, it audibly clicks (the faster the clicking, the more surplus is available).

I'll put up a pic as soon as the goop that is holding it all together dries and can manipulate it better for the camera.

All in all, I'm happy with what I see so far. Hi5 on the design, looking forward to maybe getting a few more of these things from you. As I was playing with it, all kinds of things came to mind!

Steve

[ghurd]

Of course it works  'anyway' !   

Always trust the text.
Never trust the resistor colors in photos.  Especially digital photos, that have been manipulated, then rendered, then being viewed on a monitor that is not exactly the same as every other monitor on the planet.

R5 (documented as 8.2K) can be anywhere between 1K and 1M for most applications.  500 ohms to 10M is probably just as good, usually.
Some rare operating conditions would be better served with a higher or lower R5 value.
8.2K seems like a nice place to split the difference.
The only time it is wasting power is when the dump load is supposed to be wasting power.

"First, rather than running the MOSFET.... "
Yes, that can be done under certain conditions, and they almost always are related to solar.
Usually with solar, there is no power resistor required.
It is best if the solar follows the limits I specify for the max amps, in this case that would be the panel's Isc.
( http://i701.photobucket.com/albums/ww20/ghurd1/Sketches/NoLoadSlrKit.jpg )


"Second... shunted the dropping resistor"
Not sure I follow that.
I expect this statement will confuse many people, but the Yellow LED and "a small piezo buzzer (with built in oscillator)" can both be in series with the R2 resistor.
If your "small piezo buzzer (with built in oscillator)"  is as obnoxious as mine are, it will be just as annoying as always.

"third"
I agree.  A lot!
Many people do not consider 18ma as being a consequential draw, or as being sufficent to reduce the LEDs hours of usable life.
But I think the amp draw on that one is usually closer to 3.2ma.
In tiny systems, I think R1 can go to 10K and still have LED1 be bright enough.  "bright enough" depends on the viewing conditions and who is looking at it at the time.

"When there's surplus power, it audibly clicks (the faster the clicking, the more surplus is available)"
That audible clicking will reverse as the battery becomes more fully charged, if the battery is a battery. 
And I have a gut feeling your test battery is a cap.
For example, if the battery is charged so much it is beyond the set point voltage of the controller (which can not happen if the dump load is suitable to the charging apparatus), then the clicking will be only one click indicating the dump load is dumping all the amps it can but the battery is still over voltage.
A self-driven Piezo would be going "Screeeeeeeee...".

"as the goop that is holding it all together dries "
Dude!  Ever heard of 'high temp hot glue'?  It is 'dry' before the blisters on your fingers have fluid in them.

"As I was playing with it, all kinds of things came to mind!  "
Yes.  That frequently happens.

"Hi5 on the design"
Thanks!

And thanks for an honest review.
G-

[Madscientist267]

G -

shunted the dropping resistor

Just got rid of it because the peizo is very small and doesn't emit much sound as is, so rather than removing the 3.3K for the yellow LED, I just ditched the LED altogether and jumped across the resistor, leaving the peizo connected directly to the FET.

I have a gut feeling your test battery is a cap.

Actually no, the test battery is a 5AH SLA, with a 'simulated' solar panel consisting of a 15V supply passing through a 4R7 5W power resistor. At the time of completion, the moon just wasn't reflecting enough light to send it into dump mode 

It clicks instead of beeping because I did actually end up making a small nichrome resistor of ~1 ohm, and the controller quickly dissipates the excess, enough so that there is no perceivable tone coming from the peizo. An interesting side effect of this is however, that if the battery should become disconnected, the peizo buzzer goes nuts (if the panel is receiving light) because the dump/release frequency is so high (nothing to give an 'RC' time constant)...

Ahh hot glue, well, yes, and I use it on occasion, but only for very specific things. Stuff that is of the more 'permanent' variety or subject to temperatures gets the ol blue RTV treatment. It's not so permanent that it can't be removed if absolutely necessary, but wont 'run' if exposed to a little heat.

Today I am running it through it's paces, and it just so happens that there is a shelf full of 12V 12AH SLAs that are just sitting there rotting, slowly initiating sulfation. I got no complaints from the boss in bringing in my new 'toy' since it's a symbiotic thing - I get to test the dump controller, he gets free insurance (for a while anyway) on the batteries that I charge with it. Win-Win.  Doing very well so far, it's working on the second battery as I type.

As for the 'its connected and running LED', I don't really need more than just the quick flicker of one of those red flashers from Radio Shack, etc. It actually would give better visibility for where I intend to use it anyway. Gotta ditch the parasites everywhere I can with this system.

When I go to build the real deal equalization dump controller, The kit will pretty much be built just as designed with little modding, if any.

I noticed tho that there are a handful of resistors left over from building the first one; are those the alternates for using it as a LVD? I want to build one of those as well for the DC 'mains' coming from the 8D.

Also - I cheated a little on this first controller - I used a single 'shady' 44N instead of the ones that came with the kit. I figure a failure here is of minimal consequence, but it seems to be doing well so far. I'll probably use the 'extra' real trannies for the master LVD when I go to build it, a more critical use, methinks. It will have to support a 750W inverter, as well as a few other 12V loads (although not very likely that much power at one time haha).

I'll take a pic of what I have so far very shortly (probably on my lunch break) so you all can see what I've come up with.

Steve

[Madscientist267]

Here they are, as promised:



The inner guts of the dump controller. The peizo buzzer and green LED are just 'tacked' right now, as I intend to fold the leads over on the peizo, and replace the green LED with a flashing red one.

The dump resistor is ~1 foot of #24 nichrome wire, crimped into some open-loop spade connectors, with one leg from each on either side slipped into the internal board mounting holes in the enclosure, with the other bent back to provide a solder point. For this application, it gets warm, but not hot, so I was not concerned with any kind of heat dissipation mechanism. If you do something like this, with more than a few watts, I'd HIGHLY recommend something OTHER than just open coil nichrome as a dump load. You've been warned!






The front cover. The switch is the 'ok shut up already' button for those times when the battery is full, I don't have anything else that needs juice, and I'm tired of listening to the clicks. The small hole on the right hand side is so that the peizo unit can actually be heard. It's not very loud, and needs all the help it can get.






The system with the panel, battery, and controller, with my trademark pack 'o smokes for size comparisons.

[freejuice]

Nice,
 I like those little controllers, Nice setup, I realize you are dumping some low watts but in the same box...eeek! I just got a few more parts in today myself!
 Thanks Glen for the a swell product and thanks for the share Mad267

[ghurd]

Looks good to me!

C1 is for a bit of RC time delay.

The extra resistors are for changing the hysteresis mostly.  If the hysteresis is increased a whole lot, the controller becomes the LVD circuit.
But they can be used for other things too, like 3.9K for R1 to reduce the green LED drain a little more, or 1.8K or 3K for R2 to make the yellow LED brighter.
Everybody has there own ideas about what is best for them, and I tried to get enough parts in the pack to make almost everybody happy.

It can be pretty forgiving of part values and still work perfectly fine... except for the ZD1, Pot and RX area.
I did some extreme part value changes in the prototypes trying to see the effects.
G-

[ghurd]

Looking at that panel closer, I have to agree with Freejuice.
That panel is about a 5W?  Maybe a tad more?  That's a lot of heat in the little box.
G-

[Madscientist267]

At one point, I calculated it out to ~8W or so, using the whole OTV x Isc method at high noon summer solstice, yadda yadda...

Real world power (especially as it ages) is probably a tad less, yes. But the resistor doesn't seem to get very warm at all. Granted, most of my tests have been done with the box open so far, feeling it out as it goes.

I'm actually more concerned that if the MOSFET should short, then I'd have a serious problem on my hands. The battery fuses (that would be using this) are all 10A fast-acts, but there's still a chance a decent amount of heat could build up in that short amount of time before the fuse goes.

The pulses are so quick that no real heat builds up (or so it seems ATM), but of course, a watt is a watt is a watt, so yes, you're right, it could theoretically become a problem.

I'm more likely though to forget to rotate the panel back into the sun than have any kind of problem with the heat from the nichrome.

I do keep a close eye on it during my simulations, since the sim is an 'ideal' sun, and doesn't have cloudy patches or drift away from the normal of the panel, etc etc.

I know one thing, LMFAO - with the flashing red LED on it and closed up, I don't think I would even go anywhere NEAR an airport looking for sun... hahaha They'd have a field day with me over this one  

Steve