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Discussion in 'Home Power and Microgeneration' started by Sparks, Sep 17, 2003.

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  1. Sparks

    Sparks Guest


    I have seen A Briggs and Stratton BSP7500LE generator, and wondered if
    anyone can make any comments on it?

    I was thinking of building it into an automatic system, where if the grid
    power fails, it would kick into life (it has an electric start) and supply
    power to the house...I would build a microcontroller based circuit that
    would wait for set periods of time, shut off the main incoming supply etc..)

    It is 6000w
    It has a 13hp Vangard engine
    It has two 16a 240v outputs (I really need one output I can draw all the
    power from, but it should be easily modified!)
    It is 74dB @ 7m
    It is petrol
    It is 105KG
    It has a 16 Litre tank
    It will apparently run for 7h 40 at half load on this 16 Litres

    It looks like a nice bit of kit!

    It doesn't seem all that expensive (980GBP)

    Thanks for any comments!!

  2. The B&S 13hp Vanguard is a good engine. But I really
    have a bias in favor of manual transfer switches.
  3. Sparks

    Sparks Guest

    Yes, I was at first thinking of this, but then what would happen if there
    was a power cut when we were not in...

    I was thinking of connecting the control circuit up to my alarm, so if the
    power fails when the alarm is set (i.e we are not in) it would know not to
    fire up the generator for say 5 hours - then after 5 hours, it would run the
    generator for 30 minutes, to keep the fridge, freezers, and alarm system
    batteries charged, then wait another 5 hours or so, and repeat - then if the
    alarm was unset, it would then realise we are home, and fire it up

    It would consist mainly of a 100A contactor on the grid feed, activated by
    the grid feed via a relay connected to the control circuit - this way, if
    the grid fails, the contactor would open - then if the grid comes back on,
    it would require the control circuit to click the relay to reactivate it -
    therefore greatly reducing the risk of having the generator, and the grid
    connected together (messy!!) The generator would need a 40A or so contactor
    also, this would be activated from the generator output, again via a relay
    connected to the control.

    Trouble is, Contactors seem fairly expensive!
  4. Sparks

    Sparks Guest

    Another question I have, is regarding storing petrol

    Petrol apparently goes off, and you end up with a gooey mess in the pipes

    Is there a product you can add to the petrol to stop this happening, or at
    least delay it for a while!?


  5. Dave Hinz

    Dave Hinz Guest

    In the USA, we have a product called "Sta-Bil" for just that purpose.
    Works well, from what I've experienced. I'd be surprised if it didn't
    exist in your part of the world. Automotive supply store, perhaps?

    Dave Hinz
  6. MSH

    MSH Guest

    If you are not there opening the doors, your refrigerator and freezer will
    be fine for 5 hours or even 10 hours unless there's a heat wave. If you're
    just coming from work, all the complicated things could be skipped. If your
    concerned about it happening while on vacation it could be a different
    matter, but how often does the power go out that long?

    Does that genny have an electric choke? That is key to remote start. More
    complications as you need to program the choke to open after starting. I
    have a nice 10kw Honda with no electric choke. Still have to go out and
    start it.


  7. Dale Farmer

    Dale Farmer Guest

    In most areas of the US, the electrical code requires that there be no
    possible way for a generator to be connected that it could backfeed
    power into the grid. This is accomplished by mechanical interlocks on
    the switches, or a switch that moves the load off the normal grid powered
    panel over to the generator powered panel. This is because of the number
    of electrical linemen who have been killed or injured by home generators
    backfeeding into the grid after weather damages knocked down wires.
    Installing this device is almost always ruled by electrical inspectors, and
    your insurance company, to be a permit job. Thus you need a licensed
    electrician to go pull the building permit, install it in accordance with all
    the safety rules contained in the electrical code, and then the inspector
    has to come and inspect the job before it can be turned on.
    This really is something you ought to have done by a licensed
    professional. Many ways to kill someone or burn down your home if
    you make a mistake.

  8. Sparks

    Sparks Guest

    Hmm, looks like the BST9200M Transfer Switch @ 210GBP

    Is the safest option....

    Seems a bit pricey for a switch though!

  9. mark Ransley

    mark Ransley Guest

    you have a manual choke, and how would you disengauge the starter? It
    wont work. Get a manual transfer switch for 200 $ us . Generators
    should not be left alone unless designed for auto use.
  10. Sparks

    Sparks Guest

    Well for the manual choke, I would simply use a sevo of some sort

    and the electric start, currently works on a 3 position keyswitch - off -
    run and momentry start
    I would connect to the back of this, and have an elecronic circuit do what a
    hand would normally do - switch to run, then swtch on the starter for 2-3
    seconds - then it would check to see if the thing was running - if not, it
    would wait a bit, and try again.

    This is all just in my head at the moment!
  11. mark Ransley

    mark Ransley Guest

    and how would you time the choke, and how would you tell if the motor
    starts. and if it doesnt start thats another problem . that isnt a big
    generator , loads should be put on in steps so it doesnt bog down, a
    manual switch is still safer, I have one, and feel safe with it
  12. Ian Stirling

    Ian Stirling Guest

    I'm contemplating something similar, if rather smaller.

    Inside goes a 800W generator.

    As it does not have automatic start, or choke, there is a bit more to do.
    I plan to add an automatic choke and fuel-shutoff (R/C servos) and a little
    motor with gearing to wind up a spring (ex washing-machine suspension) and
    then use it to pull the starter cord.

    Add 5-10 car batteries from the scrapyard, and it can use whatever power
    is spare to charge them (have several spare 40A 12V PSUs that can be tweaked
    to 13.8V.) and an inverter, and I can run my minimal loads (around 50W)
    for a couple of days with occasional use of microwaves/... before firing up
    the generator for few hours to replace the charge.

    Even the onboard tank could last a couple of weeks.
  13. I own two lawnmowers with Briggs & Stratton engines that have
    automatic choke. The choke butterfly valve is held normally-closed by
    a small spring. Intake vacuum acting on a small diaphragm overcomes
    the spring once the engine fires up.

    Lots of automobiles used a heat pickup off the exhaust manifold to
    warm a bimetal element to release the automatic choke.

    Gordon Richmond
  14. Sparks

    Sparks Guest


    Thanks for the tip!

    I took a trip to my local auto warehouse, but they have never heard of it!

    I then when to a little local lawnmower shop, and they have orderd it fro

    Enough to treat 100L was only £7 - so that's good!
    ....although I garantee it will be cheaper in the US!
  15. Sparks

    Sparks Guest


    Thanks for the tip!



  16. Sparks

    Sparks Guest

    I have actually already got this generator, I just wanted to get an honest
    opinion ;-)

    I have put the generator in a large box, and installed a large fan blowing
    into the box
    I have attached a metal pipe over the exhaust, and directed this out the
    side of the box
    (The pipe is about 7cms wide)

    I have just lashed the pipe over the exhaust hole, as I figure the +ve air
    pressure in the box will stop any fumes escaping into the box (if the fan is
    running, and the generator is not, there is a very slight air movement out
    of the pipe)

    My question now, is how do I know if the generator is overheating or not?
    I would like to be sure the fan in the box is powerful enough - The lid of
    the box is hinged, and when it is shut, there is a 4cm gap the entire length
    of the lid (about 1M wide)

    When the fan is running, there is quite a draft coming out of this gap

    I can take a photo of it, if this is of any use!

    Any tips would be appreciated!


  17. Ian Stirling

    Ian Stirling Guest

    I used a probe attatched to the cylinder head to measure it.
    Go look round local stores for electronic thermometers with remote leads
    that read up to at least 70C.
    Attatch 2 or 3 to various bits in free air, then compare the temps under
    max load in and out of the box.

    I would then obtain several thermal fuses, or resettable thermal breakers,
    or thermostats, and wire a relay across the engine kill switch, so that
    it killed the engine in the event of overtemp.
    I would then also arrange a couple of bits of steel so that they drop under
    gravity if a fire occurs when a fusible link melts.

    Maybe overkill.
  18. James Storm

    James Storm Guest

    Unless it has an automatic choke it will need assistance to get running any
    way. I am working with a similar unit but with the Generac branding (owned
    by Briggs).
    It needs choke to start hot or cold.

    Product in the U.S. called Sta-Bil is a gasoline additive to add storage
    time of 1 year or more.
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