zener diode with mcck onan control-o-matic genset?

Discussion in 'OnBoard Electronics & Controls' started by sdowney717, Nov 22, 2011.

  1. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi sdowney,
    My apology, I feeling the pressure of flying and forgive me if I have it all wrong. The attached sketch is what I think you have. I can see from your circuit diagram that the load current is sensed via the current transformer.
    Help me out, how your 3 x 12 Volt battery banks are connected.
    For me, your schematic is difficult to decipher, You mentioned, you have a new 3 KW inverter from 12 Volt DC to 120 Vac (primary 300 Ampere !!!! at 80 % efficiency secondary 25 Ampere AC)
    This 3 KW inverter has an overload current sensor and shuts down the 3 KW inverter and the 3 KW inverter has to be manual re-started, should an overload (or short) has occurred.
    I cannot read what it says at the right-hand side at the top under "Schematic"
    to GWS or something like that etc. Could you elaborate on what is written? The rest I am able to grasp what the functions are of all the transistors, fuses etc.
    Bert
     

    Attached Files:

  2. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    well the battery convertor charger has 3 bank charging. One positive wire to onan starting batt. One pos wire to engine start - house battery, one pos wire to number 2 engine start - house battery. Those red wires are simply attached to a junction point not really on the battery directly.
    I also have a standard battery selector switch to select the engine start - house batteries both - 1 - 2 - off.
    picture shows the 3 red wires from charger-convertor.

    The green-black-white 120 volt power wire coming in on top comes from the DPDT relay.
    simple relay is energized when shore power is plugged in and then convertor - charger gets powered up from shore power.
    when shore power is unplugged relay de-energizes. Power is then sourced from generator and the wire hooks up in front of the onan generator reversing contactor which bypasses the 12 volt auto starting sense voltage. Contactor is K3 on the wiring diagram. That one has 2 large NO poles and one small NC pole. The NC pole is what passes the 12 volt DC auto sense voltage.

    [​IMG]


    it says
    'to customer bilge blower motor 12 volt 5 amp max

    I took a screenshot of the area called schematic and they overlap
    [​IMG]

    [​IMG]

    here is the wiring diagram side of the page
    [​IMG]
     
  3. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Fine, that means all three batteries are parallel connected, just the cable resistance between batteries will be your safeguard that the actual voltage per battery is allowed to vary with a very small margin.
    But it still means that the batteries are switched parallel, just your "user items" can be selected from either the engine start or house battery.

    Yes, like I have drawn on my in hasty scribbeld jpg circuit.

    Here starts the fun for me (thank you, your jpg file is clearer than the one I have been able to download from the internet. Unfortunately I am doing last moment problem solving (cars etc) and then I am on the way to the airport, I maybe able to dial in once more, but then you will get silence for I think at least 3 weeks.

    I need to make something similair for myself.
    [​IMG]


    it says
    'to customer bilge blower motor 12 volt 5 amp max [/QUOTE]
    Just an outlet for an user item
    [/QUOTE]

    I took a screenshot of the area called schematic and they overlap
    [​IMG]

    [​IMG]

    here is the wiring diagram side of the page
    [​IMG][/QUOTE]

    The fun starts.
    Bert
     
  4. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    There are still some questions in my mind.
    1) Your inverter battery must be enormous, in view you have to cater for 3 KW at 12 Volt. That is at least 280 - 300 Ampere. At 6 Ampere /mm2 , we looking at 50 mm2 (0.1 square “or 8 mm (+/- 1/3 “) diameter copper. How big is your battery in Ampere-hour 400? 600 ?
    2) It won’t start automatically if I flip on a spiral florescent bulb., this is correct as I assume you have a energy saving spiral florescent bulb, which is approx 11 watt only. Correct assumed? This gives me an idée at what current the inverter kicks in. (your white ceramic resistor)
    3) Your charger is an 30 Ampere charger, (I read it somewhere) thus your inverter (3 KW) needs 10 hours of your charger time, or do you mean 30 Ampere primary?
    4) How do you know, that the batteries are fully charged with the charger? I assume with the alternators you have an automobile regulator with each alternator. Is this correct? i.e. it regulates the coil currrent. That stops the battery from overcharging.

    Sorry for all the questions, but it will give a better picture in what can and cannot be done by me.
    Bert.
     
  5. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    1.
    I simply get the big invertors so it can start things like the refrigerator. that takes a lot of power surge to start the compressor. So I dont care to run heavy loads all the time off the invertor. Idea was to not run the generator if the main engines are running. I tried a 1500 watt, 3000 watt surge inverotr and it could not start the refrigerator.
    I feed it with 2/0 copper cables less than 6 feet long.
    I can turn it on and off remotely.
    I wired all the boat outlets to this on a single circuit and include a gfci. Fridge is not on GFCI, which is good because nuisance trips and your food will thaw out. Basically the GFCI is outlet and gets power after outlet from dpdt switch. All wire connecting outlets is 12 gauge exceot 10 gauge is used from invertor to dpdt switch.
    Power is fed to outlets from two sources, from the breaker box which has shore and generator power, other source is invertor. Power from 2 sources comes into a single DPDT switch 20 amp rating, off,on,off. So a transfer switch which switches 2 poles. This way I can select invertor or gen-shore power with click of single switch to outlets. Invertor loads all I care about is running boat outlets.
    Generator versus shore power selection is by way of a large rotary 2 pole switch, typical application for shore-gen selection.
    When gen is selected all power to breaker box comes from gen, etc...
    Except for the convertor - charger, which if the you plug into shore power, automatically is on. Makes it nice to just plug in and dont have to remember to throw switches. So this means convertor - charger 120 volt AC power is not routed threw the boat breaker box. It does have internal ceramic fuses.

    2) "It won’t start automatically if I flip on a spiral florescent bulb., this is correct as I assume you have a energy saving spiral florescent bulb, which is approx 11 watt only. Correct assumed? "
    yes, and that resistor is soldered into the sensor board A1 on the scematic. Circuit will auto start gen with about a 40 - 60 watt load, I think. Changing the ohms on that resistor affects the sense cutoff to auto start.

    3. Yes 30 amp, but only 20 amp continuous, I think. There is a 30 amp meter on the front, but I will look again. If you ran the invertor hard up to capacity, that convertor could not keep up. batteries would run down. But that wont happen if you run the generator and dont load the invertor. So if boat is anchored, then run gen and turn off invertor.

    4. "How do you know, that the batteries are fully charged with the charger? "
    Good question and it pretty much just works for years I get from batteries at least 5 to 7. I actually bought some nice used batteries from Advance Auto for half the price of new.
    I run flooded lead acid and this simple charger keeps up. The voltage is set so as not to let the batteries gas out hydrogen. It is a single stage charger. Fancier chargers are out there. Alternators are on each engine. They are like a car Delco unit and are single wire self internally regulated 78 amps each.
    About 10 years ago, one battery developed an internal short and that charger managed to keep everything working even though it got quite hot.
     
  6. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    I like to agree to some names first.

    Relay (in your case) : the unit which switch at 12 Volt something

    Inverter. This is the unit which converts from 12 Volt to 120 Volt AC and senses at the 120 Volt side that a load is connected sufficient to pull the internal relay in to start the inverter. The inverter is big enough ( 3 Kw) to allow a fridge or deep-freezer to kick in.

    Charger: Is your unit which converts from 120 VAC to 12 Volt (13.8 Volt and not 14.4 Volt I understood)

    Alternators: They are on your diesel and provide power when there is no shore power to charge your 3 parallel connected batteries.

    Old inverter: This is now replaced by you, with the more powerful 3 KW inverter and is no longer used

    After a fantastic holiday in Holland , having gone through your threads and screened all the circuits with a magnifying glass, I came to the conclusion that your only problem you have is , that you like the charger to be switched on and off automatically. For this we need to make an electronic circuit which senses the battery voltage. The problem is, will it be enough to sense the voltage of 13.8 Volt, which is the gassing voltage of a lead acid battery. The second problem is that the charger is charging the battery, while we have to figure out in how far the battery is charged. The third problem is that with the charger connected to the same plus and minus of your inverter, you mentioned somewhere that the inverter then does not automatically switch off. (Which puzzles me)


    Here is my proposed solution.

    1) We have a relay or MOSFET transistors which can DISCONNECT your batteries to your charger and all other circuits connected.
    2) We have 6 Super capacitors in series which are connected to the 12 Volt side charger and inverter, etc.
    3) By disconnecting the batteries from the charger, for that short period, the super-capacitors take over, and we can then measure the voltage of the disconnected battery.
    4) If the Voltage is too low, the charger carries on charging and the relay does not remove the charger from the 120 Volt AC
    5) If the Voltage is long enough at 13.8 Volt Volt (or a acceptable voltage) , we could via the microprocessor disconnect the charger from the 120 Volt AC until the microprocessor has decided that it is time to connect the charger again.

    Let us at this stage not argue about cost. Just discuss at this stage only whether this is solving your problem.

    Bert
     
  7. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    Its been a while since I thought of this so I will have to rethink what I was thinking.
    Actually, it already does turn off the DC output from convertor- charger to the batteries when the engines are running. Yet somehow knows to help with a starter boost. Must sense when the engine starts running from the coil outputs.
    It is the blue wire in the picture I uploaded of the convertor. It will sense from both engines. Although It still runs the AC part of the convertor

    here is a manual listing some of the qualities
     

    Attached Files:

  8. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Sdowney, please help me out. What do you understand is a convertor-charger. Either you have a charger which takes 120 AC to 12 Volt DC and is solely used to charge batteries. Or you have a converter which convert AC to AC or DC to DC, or AC to DC or DC to AC, but I am battling with the term convertor-charger. Is it doing something else than charging batteries?

    Have you ever considered to approach the manufacturer and put your question to them?
    Bert
     

  9. BertKu
    Joined: May 2009
    Posts: 2,452
    Likes: 39, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi Sdowney, I hope that I understood your problem correctly.

    1) You like it that the charger switch off when the diesel with alternators kicks in.
    2) The alternators automatically stop charging the batteries when the batteries are full. But the diesel carries on running (this you don't like and like to see a solution for this problem)
    3) You don't like it, if the charger is on shore power and it does not switch off, therefore you selected 13.8 Volt to protect the batteries. You like to see a solution for this problem.

    Have I understood your problem now correctly?
    Bert
     
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