How do you limit amps for charging?

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

  1. pistnbroke
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    pistnbroke I try

    lamitaspatia does not know anything about alternators or batteries ...you cannot overload an alternator as it is self limiting for current and there is no way to damage a voltage regulator in normal use ....unless of course you are pulling leads off when its charging ...from a normal alternator regulating to 14.4v you will get a max of 25 A per 100ah of capacity .....if you want to know how to charge starting and house batteries from two alternators its very easy and the whole current capacity of the two can be used to charge the house battery once the start battery is up ...all totally automatic and very cheap.
     
  2. thudpucker
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    thudpucker Senior Member

    The Alternator works as an Electro Magnet.
    The little 3 volt circuit provides the Magnetism to make the voltage.
    The 3 volts gets to the Alt because the circuit watching the Battery (the Regulator) sees a "Lo" condition.
    The 3 Volt circuit is 'adjustable' and will be shut off when the circuit watching the Battery Voltage sees a "Hi" condition.

    SO....the simplest answer to your question on controlling the charge is an Alternator with an internal Voltage Regulator, or get some fancy Voltage sensing circuit, made up by a Tech that will take the time to make sure his work is not fatal to something.

    The problem with a series of batteries and ONE Voltage source is this.
    Suppose four batteries. Three are good. One seems to need a charge all the time.
    The Voltage regulator will keep charging, trying to build up that weak battery.
    Meanwhile the good batteries are being "Cooked"

    OR....One Alternator/Regulator, and a Rotary switch to send the charge to the battery your Volt Meter across Each Battery tells you one is low.

    It gets complex if all the batteries are connected to the same circuit so you have to know to do all this Testing and Recharging after the 'end of day' when those batteries are disconnected from the system.

    What your asking for just wont be automatic and Robotic.
     
  3. pistnbroke
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    pistnbroke I try

    " The little 3 v circuit " I have been an expert on alternators for 30 years and never hard such rubbish.

    " problem with a series of batteries" God the batteries are in parallel..

    "the good batteries will get cooked" NO NO the bad battery will get cooked

    " what you asking wont be robotic or automatic" well it is on thousands of british Narrow boats and other craft around the world.

    Thudpluckcer best stick to your chosen subject .....
     
  4. thudpucker
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    thudpucker Senior Member

    The post is for a guy who don't know how to do what he wants to do.
    So I made it simple for him to understand.

    The (tickler circuit) 3v circuit (which is varied by Time) you've never heard of is the small voltage across the coils to make the magnet for charging. surprised you didn't know about that. It's pretty common and has been in use since the Generators first went onto Vehicles back in the 20's.

    It was controlled by Relay points back then, but more recently Transistorized switching circuits.

    I did not say batteries in series, I said what I meant, a series of batteries, as the poster defined, he has four IIRC.
    To control the charge to each battery separately can't be done if all the batteries are connected.
    If you think other wise, I'm your best Skeptic.

    His original question was how to, or what was involved to control the Charge. I put it in simple terms for him.
    Splitting hairs and slander is not helping the poster.
     
  5. pistnbroke
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    pistnbroke I try

    sorry thudplucker your post is technically inacurate and unhelpfull to the guy....they did not have alternators in the 1920s thay had dynamos ( yanks call generators) and the concept of excitement is totally different .... best delete your post.
     
  6. thudpucker
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    thudpucker Senior Member

    Here's a little story from the past to explain that "Tickler" circuit.

    Way back the Generator had a separate relay the old guys who didn't understand why, just called it the tickler. The points in it chattered all the time. "What the heck's that thing doing?" my Uncle used to say.

    So the Tickler points would stick sometimes and really make the Generator charge about to it's max output and burn out lights and other damage not to mention cooking all the water out of the Battery. Usually one end cell.

    The Generator is trying to charge the Battery all the time. When ever those points are closed, current is flowing from the Generator to the Battery.
    Something has to control that. Eventually pretty sophisticated Voltage Regulators came into existence.

    But back then.... to monitor what that Tickler was doing, some smart guys put a Head Light bulb, in those days, and an old Heater Core Rheostat in the line between the Tickler and the Generator field.
    So now, you see the Bulb glowing or flickering weakly as the Generator is working.
    When you wanted it to charge more you opened the Rheostat a bit and more current would flow. The Headlight bulb would get brighter.
    If you wanted the Charge to pickup, like you were going to run an electric winch etc, you just turned the light bulb on a little brighter.
    That was real common in the 20's on Machinery and Boats.
     
  7. thudpucker
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    thudpucker Senior Member

    Sorry Pistonbroke, my post is technically correct, your interpretation is incorrect.
     
  8. pistnbroke
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    pistnbroke I try

    Its 2010 not 1910 ..beleive me my friend what you are saying is of no help to the guy and I am problably the only person reading this who knows what you are on about ...

    you are mixing voltage regulaton with current regulation by sloppy use of terms ....regulation of both voltage and current were neccessary back in 1920 but no current regulation is required with an alternator
     
  9. thudpucker
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    thudpucker Senior Member

  10. Submarine Tom

    Submarine Tom Previous Member

    To the original question/post: Get a smaller alternator.

    -Tom
     
  11. pistnbroke
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    pistnbroke I try

    Tom please dont join the other guy ..I have told you you need a 120A alternator to charage the bank in the best possible time...and of course keeping the batteries fully charged is he way to a long life ....a smaller alternator will only take longer to charge them and by modern standards 50A is small.. Its the voltage of his regulator going to 17v that has let him down ...
    There are 3 systems for this
    Use one alternator and switch it to the house bank when the starter is charged.
    dont like that as you always forget.

    Modern systems use two alternators ..the simplest is to have one for the house and one for the starting ...No problem but you do waste the current available from the start alternator once it has charged the start battery.

    the modern way is to use the surplus current from the start alternator to help charge the house batteries ....you need one of these and its automatic.(see pic)

    A VSR is not so good because when it connects in the house battery the starter battery discharges into the house battery which tends to defeat the objecet.
     

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  12. lamiataspaska
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    lamiataspaska New Member

    I have some thing that makes the start battery charge first, and then it switches to the house battery bank. What I plan is to devide the bank in two and have a switch to choose which half to use. Those switches have a state 1, 2, 1+2, and unfortunately for me 0. So if I forget it to zero, after the starting battery is charged, the gadget will switch to charging the house battery, but it will be an open circuit. Will that burn the generator?
    And is there any famous trick to lower the 14.4V to 13.8V? I can put a super long cable so I get some voltage drop, but it seems like a stupid idea...
     
  13. michael pierzga
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    michael pierzga Senior Member

  14. Bglad
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    Bglad Senior Member

    Newmar makes a battery isolator (http://www.newmarpower.com/Battery_Isolator_Integrators/Battery_Isolator_Integrators.html) which would solve your switching problem. The mechanism they use to keep batteries separated except for charging causes .7 to .9 voltage drop to the batteries. It would be a bandaid to use and you would still need to check the voltage to make sure it is correct after you installed it. The proper course of action is to install a separate alternator and regulator with capacity and controls required to handle the house bank. Expensive not to if the result is another batch of cooked batteries.
     

  15. Landlubber
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    Landlubber Senior Member

    "A VSR is not so good because when it connects in the house battery the starter battery discharges into the house battery which tends to defeat the objecet."

    ...which is why I connect the house batteries to the VSR and they then switch to the start batteries after looking after the house....modern engines start so quickly that there is bugger all drain on the starter batteries, the house batteries are of course usually seriously knocked about

    ....pistnbroke.....what do you reckon about that...am I a goose?
     
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