generator start stop with voltage monitor for off grid app

Discussion in 'The Projects Forum' started by kd7ura, Apr 15, 2010.

  1. kd7ura

    Thread Starter New Member

    Apr 12, 2010
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    1
    New guy here! apperantly i started to hijack a thread, but here goes
    ive got a gen with the auto start built in , im looking at a low voltage detector and voltage monitor circuit with leds, trying to figure out how too put them together with a relay to trigger the auto start on the gen.
    i need the relay to close to get gen to auto start when the battery bank reaches low voltage point of 11.89 VDC stay closed untill battery bank reaches full charge of 13.8 vdc then open relay to shut down gen.
    i have two wires coming from the gen by putting them together it starts,runs. and shuts down when you seperate them. the two wires draw 12volts from the generator battery to trigger the auto start feature.
    the gen will run 220 v to two xantrex inverters , one on each leg and they will invert and charge the batteries,
    ive looked at the mc34161 detector chip for voltage checking and LM3914 for the led display monitor i need a recomandation for a relay to trigger the gen and how i would put them together. Ive got a relay from discounthomeautomatiom.com part#EELK924x i think will work for the gen
    just not a good electronics guy need to know if this setup may work..

    im thinking of tying the 3 circuits together so the relay will trigger when the low voltage led turns on and shuts off the relay when the high voltage led lights up. i think it should simple enough to start with .
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Using a low voltage alert circuit to latch the relay at 11.89v then a zener to unlatch it when 13.8 is hit would do. Instead of lighting a LED for the LOW BATTERY circuit, latch the relay.

    Using a latching relay, you need only pulse it to change states. You do not need to continually supply power to the coil.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If you don't compensate for the battery internal temperature, you will be undercharging or overcharging your batteries.

    You need to consult the manufacturer's datasheets for your batteries, as to the recommended charge voltages, float voltages, etc. and the temperature compensation to be used.
     
  4. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    Latching relay where and what part number im a short timer when it comes to electronics and the leds are just for a monitor of the voltage, the guy im making this for is a bit blind and wants to see the pretty lights.
    im about to place an order for a bunch of parts got the elk924 relays for another setup on a larger inverter for the autostart figured id keep using them but what works better ill doit like the idea, show me the way! thank you!
     
  5. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    Also on the batteries the inverter is programed to charge the batts whenever there is a line voltage to draw from,(gen) the voltage i posted are the settings i use to keep the bats in a health state for as long as 12 years keeping the low cutin at 12.5 will run them a few more years but most people get upset when the inverter shuts off when (there is plenty of battery power) we run the bat voltage as high as 14.5 to balance all the sells once every few months my neighbor hood is 100 % offgrid about 2000 households we like free juice!! thanks guys i appreciate the help
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    You really should "balance the cells" more often than once every few months. Running them down so low lets the plates start to sulphate.

    If you charge them up to 14.5v (temperature compensated, of course) every few days, you'll keep the sulphate off the plates and the electrolyte stirred up.
     
  7. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    thanks for the info on the batts you dont have to convince me its the people i make repairs for that have to listen.
    they tend to shut of the inverters 30 day exersizers for the batts to save on gen fuel.
    most dont have enough solar panels to let the charge controlers do a monthly
    they have a mindset on a three to four year replacement schedual for there golf cart batts. mine on the other hand are at full charge 99 percent of the time and are on auto EQ from the panels charge controler. 24 L16 trojans arnt cheap they get what they need and dont see much use except when im doing gunsmith work.

    ok what kind of circuit whould i need to operate the latching relay?
    would i use the mc33161 or would you recomend a different Voltage detector.
    i can build circuits from a schematic but designing is not my forte
    i can follow instructions and test as i go. the schematics iv seen im not sure about what i would do to get the voltages to function in the ranges id need.
    iv got a variable power supply to work with and an o scope that works on one trace
    i can get things built if i have a guiding hand.
    any free programs out there that would help me learn a bit about the circuits as im a poor man these days as i doo alot of expencive work for cheap.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Don't have time to give you much at the moment.

    Linear Technology's LTSpice is a good and free Spice simulator tool. There is also an LTSpice support group on Yahoo! Groups.

    Google LTSpice download.
    Join the Yahoo! group for lots of additional component models and help.
     
  9. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    thankyou,, also found this site as well http://www.tech-systems-labs.com/freesoftware.html lots of free software. there is another link where you help a gent with a low bat cutout with a reseting led he wanted it to monitor the start bat during startup "that was neet"
    where i got the info on the lm33161 the pdf's on the chip confuse me a bit as to how i would implement it with the relay for both the high and low voltage set points, would i use 2 of them, one for high etc,, going to search for latching relay thanks for you assistance. semperfi
     
  10. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    been looking at your other post for the low batery detector you helped smoke maker with, by adjusting the r2 resistor we can change the low detect voltage.
    im looking at the MC34161-D.pdf fig 17 dual positive low voltage detector.
    the graph next to it shows the led off on points for the V inputs.
    im trying to under stand this part? if i set the resistance of Vs1 to 12V and Vs2 to 13.8V would this cause the led to change states at these voltages?
    the relays i have are 12/24v adjustable with both pos or neg triger inputs that will latch the relay with as little as 1.2ma http://www.elkproducts.com/products/elk-924.htm would i just set the pin 5/6 to the neg trigger on the relay and tie the positive input on the relay to pin 8 with Vcc to get what i need to trigger the start function on the gen
     
  11. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    i downloaded eagle and put together a circuit "i think im getting somewhere:confused: not shure how to check if what im doing is going to work.
    ive got ltspice installed can i move the file over to spice somehow??
    and how do i set it "LTspice" up to work with the LM3914 chip?

    Could you take a look at my circuit and let me know if im close??
    i think im digging a hole and dirt is falling back in so i cant go any deeper without a bucket!
     
  12. kd7ura

    Thread Starter New Member

    Apr 12, 2010
    27
    1
    iv been thinking of addin two more relays to wrk solinoids for generators. without an auto choke. we would have three total, one each for, run, start, and the choke/diesel gloplug.
    woul be a nice setup to build. so far iv setup a lm3914 with the led's to monitor voltage and triger transistors off the #1 and #10 led.
    they lead to a mosfet to trigger and hold the run relay im hoping i have it setup right , im not sure if im following the right flow patern through the circuit?? an i dont know much about the packages for caps in the eagle software. glad i could use it though actualy spent a hole day moving parts around the board just for the fun of the autorout function

    thanks
     
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