How do you limit amps for charging?

Discussion in 'OnBoard Electronics & Controls' started by Raftman1979, Oct 20, 2008.

  1. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

  2. pistnbroke
    Joined: Jan 2009
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    pistnbroke I try

    Rodec ..perhaps you should read your post no 23 item 2 .above..says SERIES
    As for Masalai ....no need to read that stuff I wrote it for them......

    any way getting tired of all this ...so many who cannot see the wood for the trees....

    To Summerise

    Any battery suitable for starting or supplying Aux loads can be charged direct from a vehicle style alternator . outputs vary a little by make usually 14.4-14.7v .charge currents unlikely to exceed 25 A more likley 15 A and falling.
    Small gell batts can be floated by putting a diode in series to drop the volts by 0.7v but check the label and your alt output volts ..might not be neccessary ...

    All said
     
    1 person likes this.
  3. apex1

    apex1 Guest

    Not bad that advice.............:) may I recommend a better?:D

    http://www.victronenergy.com/upload/documents/Book-EN-EnergyUnlimited.pdf

    and........without being tooo rude..... almost all of the audience providing vicious remarks above, are well advised to have a close look!:D

    @ pis..and.broke
    Any battery suitable for starting or supplying Aux loads can be charged direct from a vehicle style alternator . outputs vary a little by make usually 14.4-14.7v .charge currents unlikely to exceed 25 A more likley 15 A and falling.
    Small gell batts can be floated by putting a diode in series to drop the volts by 0.7v but check the label and your alt output volts ..might not be neccessary ...

    All said

    Yes... all said.................... much wrong!:!:

    Regards
    Richard
     
  4. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    apex1, Have downloaded the pdf and having a good read (72 pages) - did you write that too pistin? - I'd have thought looking at the beach babes up there would be a 100% distraction? but is there a bar where one can get beer at reasonable prices whilst watching? :D:D Enjoy the good life sir, I'm only jealous....
     
  5. apex1

    apex1 Guest

    And.... was it worth reading? ;) have I won the T-shirt?
    Our beach babes here in the northern baltic region I think are amongst the most attractive worldwide! And usually nude........
    So I am not sure if you can focus on your beer. If it comes to prices and quality, you know Germany has the lowest prices for food at the highest quality level worldwide?!

    -did you write that too pistin-
    ----- yes mainly;) but everyone is invited to feel recognized.

    Regards
    Richard
     
  6. Frosty

    Frosty Previous Member

    Pistnbroke is closest. Only I don't agree with 14.4 I set to 13.8 but it could be temperature thing.

    You dont have to interfere with the current crossing the slip rings IE feild current. you can put a pot in the voltage sensor wire to the reg. This will fool the reg into thinking the batt is low and boost up the alt output.

    It will need constant monitering though keeping voltage down to what ever you want.
    With a system as this it is possible to shut down all systems and take them up to 15-16 to clean and de sulphate them up. But you gotta know what you are doing.

    If the pot is turned off it will be back on auto again.

    Handy for fast charging running the main engine.

    Errr--- lead acids only.
     
  7. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    13.8 is a bit low .and represents only a 50% charge ..batteries charged to 13.6 only last about 6 months...no doubt you are compensating for your low charge voltage with occasional boosts to 15-16v.

    remember that 14.4v is only 80% charged ie 20% sulphate and you need to go to 15.5v for 100 % charge ...problem is the battery gasses and needs weekly topping up like a dynamo charged battery on a car ( 15.3v)

    please note that the slip rings carry ROTOR current not field current thats a dynamo term.

    Of course you need an alternator regulator with a voltage sense wire to do your variable resistor trick ( most have no seperate sense wire ) and you cannot lower the voltage regulator setting only raise it
     
  8. Raftman1979
    Joined: Oct 2008
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    Raftman1979 Junior Member

    I have an electronic "smart" charger. It gives a digital readout and I can switch between charge percent or voltage. While charging, it gets up around 16 volts or so sometimes, but when it reaches "100%" and automatically kicks off, I let it sit for an hour or so and the battery is showing 13 point something volts. I've never seen voltage over 13.6 or so on a battery that wasn't receiving a charge.

    I guess when it comes to batteries and charging, if you ask ten guys, you'll get ten different answers. I guess I'll just use my idiot "smart charger" at home and my "I'm too stupid to open the hood" jumper cables that charge a car via cigarette lighter sockets for slow charging from a high-amp source. And if my batteries last 3 years instead of 4, I'll just buy new ones.
     
  9. pistnbroke
    Joined: Jan 2009
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    pistnbroke I try

    thats fine for wet car type batteries but too high for sealed types.. If you stand your battery overnight you will find the terminal voltage drops to about 12.6 ...anything below 12.5 and the battery is suspect ....nice to hear from you
     
  10. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    into the lions den

    On my cat I used to run a wire from the field coils of an alternator to a rheostat. The alternator was run from a belt that ran off the top of the outboard's flywheel. The long belt would moan and the kids would shout that they couldn't do their homework - I told them I needed some amp hours in the battery and I wanted to kick the 400 AH deep cycle battery bank in the guts. Rheostat was set low . I would pike out at about 30 Amps. Then about the third time the belt jumped off, grabbed the alternator and flung it out the engine nacelle. The family cheered. I was too scared to do it again.

    So then my mate gets a small diesel and does the same for his lovely cat. He is a sparky and just watches hydometer level and voltage - decides he wants to shove lots of charge in and winds up the field coil level. Top up comes from solar but the majority from the alternator with fiddled field coils given a boost. Like me he tried the normal alternator but it is really dispiriting to be having an engine on and seeing the current drift downwards quickly as the voltage of the battery comes up.

    I hope I am not doing something really silly. I want to make another charger out from a proper generator (they are cheap now) with the 240 generator taken off and an alternator put in its place. With no calculations I hope a big alternator will put out some charge at crankshaft revs although I could use pulleys.

    I am a little tired of being a mega amp miser - that is the reason for a dedicated fast charger on the cat. My batteries were amazing though. Bought in 1999 - I didn't charge them past 13 volts till 2001 when I finally got the good oil from an electrician. They only died last year. 6 volt deep cycle - lived aboard three years.

    Cheers all

    Phil
     
  11. catsketcher
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    catsketcher Senior Member

    addendum

    By rheostat set low - I meant low resistance - high current.

    cheers

    Phil
     
  12. white840
    Joined: Aug 2008
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    white840 Junior Member

    You can use SCC2 is a solar charge controller, regulate the power flowing from a photovoltaic panel into a rechargeable battery. It features easy setup with one potentiometer for the float voltage adjustment, an equalize function for periodic overcharging, and automatic temperature compensation for better charging over a range of temperatures... I know a site http://www.zigbee.eu/ that will help you..
     
  13. thudpucker
    Joined: Jul 2007
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    thudpucker Senior Member

    I've been working on this for awhile. There is some hope out there. My idea was a Weedeater motor, but I think the 3.5 B&S is a better deal.

    Among the things I learned so far: the GM single wire alternator is the best. The charge rate is very well controlled.
    If you want to monitor; put an Ammeter in between the Battery Plus Terminal and the Charging source. That will tell you the rate of charge. It will be high at first, and as the Regulator shuts down the field voltage the current will fall off to nothing.
    When the charge starts up; a Voltmeter across the battery will tell you the Amount of Voltage in the battery. When its at full charge you might see as much as 13.5 but you might see the rate of charge go up to 14.2. It wont stay there though and it don't seem to hurt the battery.

    One of those links has a good schematic for what your trying to get.

    http://theepicenter.com/tow02077.html

    and;

    http://theepicenter.com/tow082099.html

    and;turbo-charging-gas-engines-weedeater-genset.jpg
    weedeater-genset.jpg
     
  14. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    I have read what you have written and so that people get properly educated ......please absorb the following

    The battery will not be at 100% charge until it reaches 15.3v ..but it will be gassing
    the normal 2009 ideas of full charge is 14.4v which is the voltage beyound which it starts gassing ( no maintanece required ie topping up ) but is only 80% of true max capacity
    Alternators were not designed to have ammeters which drop the sensed voltage to the alternator and reduce charge rate/voltage

    If you charge a 100ah battery at over 25 a it will gass and get over hot ...

    your weed eater is too weak to drive the alternator but you must gear the briggs and stratton (3600rpm ) to drive the alternator at 2-3 times that speed for full output ....



    if this was usefull please leave rep if not ....ok
     

  15. thudpucker
    Joined: Jul 2007
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    thudpucker Senior Member

    It is useful. Almost too much info in fact.
    I wondered about the GM alternator's minimum and maximum charging Rpm?

    The Weedeater will go way up in Rpm, maybe as high as 8000, so if the GM has to run at 2500, it means we can have about a 2" pulley on the Weedeater and a 5 or 6 Inch pulley on the alternator.
    The Weedeater should be able to handle that if you let the Rpm build up before you connect the Charge sense wire to the load.

    The B&S will do fine with a load like that at 3500 Rpm. It has good torque attitude and good crank oiling.
    So if the B&S will be happy with 3500 and the Alternator at 2500, the pulley would again be smaller at the B&S engine.

    How about that? Am I in the ballpark there?
     
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