New Dumpload Controller using Amanda's Design

[ruddycrazy]

Hiya Guys,

          Well last weekend I found my plasmatronics PV charge controller had bitten the dust so rather than buy another commercial one I decided to make my own using the Circuit 1 from Amanda's files. I found my sla 700AH array sitting on 31 volts and my 3KW sine wave inverter was complaining about over voltage. So this project is sort of a rush job to ensure next week when I head back to work the shed array doesnt over charge again.

I made the circuit on some proto board I got from hongkong cheap and I set it up to start reading @ 24 volts then go up in 1/2 volt increments to 27.5 volts. Then the top 3 led's have BC558 transistors to control each dumpload. As my my PV can input over 15 amps on a sunny day I've decided the 27.5 volt dump will be 2 amps, the 28 volt dump be 4 amps and finally the 28.5 volt 8 amps. As the signal from the transistor is only 5 volts and the only fets I have here are IRFZ44N's, I'm going to make a seperate dump board using a TC4469 fet driver along with a 12 volt regulator. Amanda did suggest to me just to run the board off a 12 volt reg but I found de-soldering the cheap proto board also pulled the copper pad's off.

Thats all for now and as I progress along I'll put some more pic's up.

Cheers Bryan1

[ruddycrazy]

Well here's Part Two,

                     I got the dumpload board finished and working, so the next big jobbie is installing it all and ripping out all the old reduntant stuff. I had a heap of fun yesterday trying to get the TC4469 to work and Amanda came to the rescue yet again ( Thank You Amanda ). What had me stumpted was the output signal was 'open collector' which meant it would output a 5 volt pulse but not return to ground without a 'pull down' resistor. I did a bench test using my 240 volt water heater element which are in modiefied so they only draw an amp or 2 each. I used my good ol' trusty 30 volt 3 amp bench power supply and watched the current draw as the first fet turned on--- 1.14 amps, as the second fet turned on--- 2.6 amps and as the third fet turned on BEEEEEEEEP over current. So the test worked out perfect first time glady. Now the heatsink is off an old computer and the fan is a 12 volt one. I toyed with the idea of placing another fet to drive the fan then realised I had an unsed input on the 4469 which runs on 12 volts anyway. So with a link on the input back to the first input when the first fet fires so will the fan.

Cheers Bryan1

[zeusmorg]

  Nice looking work! I hope it meets your expectations and outlives your old controller.

  I always like to see good electronics designs in fruition.

[Dave B]

 Funny how similar ideas seem to come together. Without knowing much of anything I designed and built my controller shown here several years ago using 2 LM3914's 15 LEDs with adjustable range and 3 variable trigger levels.

 In it's testing phase here I'm triggering (2) 50 amp solid state relays directly off the led voltage of different levels to control hot water heating elements direct from the wild AC side. The resistors you see are just to help drop the rectified AC before the range adjustment pot of the control circuit.

 It's been through many variations and currently I am powering the circuit with a 12v motorcycle battery that is on a trickle charger for emergency backup load control when the grid goes down. Seems like high winds and power outages go hand in hand, no free wheeling for me thanks. Dave B.

[oztules]

Nice work Bryan1

I like this type of controller (all the bright leds I think). Mine was similar but used 2 quad comparator chips in place of the lm3914... didn't have any dot/bar display driver chips.

Good to see you getting on top of things over there. Next thing you will be using the 3914 for a current meter. (Your power room will become a disco with all the coloured lights)

Nice of the Commanda to come to the rescue.

......oztules

[Boss]

That is a fine project. I am rusty with electronics but very interested. Where would I find Amanda's schematics to study?

[TomW]

Brian;

I think it is in her files:

http://www.fieldlines.com/user/commanda/files

Not sure which one, tho.

TomW

[zeusmorg]

http://www.otherpower.com/images/scimages/2006/09590160.pdf

[commanda]

http://www.fieldlines.com/story/2006/6/1/84528/29208

http://www.fieldlines.com/story/2006/6/22/04750/5496

http://www.fieldlines.com/story/2006/7/21/93147/7405

Amanda

[Boss]

Yeah man there are a bunch of files there.

[ruddycrazy]

G'day Dave B,

             Mate do you reckon you could provide a schematic of how you hooked up 2 LM3914's all I have to go on is the datasheet which does give me anyway the the info I need to get 2 of them going together.

Cheers Bryan