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    How to limit a voltage at 14.5V (20A)

    Hello everybody,

    I have a regulator for my solar installation, but unfortunately it "overcharge" my batteries (it let the charge voltage up to 17V) It brings literally my batteries to bubble over.

    So I constructed a "limiter" to work like a switch (v>14.5 stop the regulator, v<=12.2v restart it). It works but I would prefer an other solution.

    I would like to limit the voltage at 14.5v - but the current can go up to 20Amps.

    My first guess was to use a Zener diode to limit it, but I cannot get one of 20 Amps here in Mexico. :-/

    I have some power transistors, can I use them somehow ?

    Thank you very much for an answer.

    •   Alt19th May 2017, 18:12

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    Re: How to limit a voltage at 14.5V (20A)

    Why not disconnect the charging source instead of shorting it?



    •   Alt19th May 2017, 18:21

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    Re: How to limit a voltage at 14.5V (20A)

    The charging source is my solar panels output, I would like all the process to be fully automatic (ex. when I'm not at home...) and protect my batteries.



    •   Alt19th May 2017, 18:25

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    Re: How to limit a voltage at 14.5V (20A)

    What you want is a DC-DC converter (probably buck/boost,
    or boost capable in some other topology) capable of standing
    off unloaded panel low temp max V, and producing a controlled
    charging voltage. Like, say, a "solar panel charge controller".
    eBay search turns up many (pedigree, is on you).


    1 members found this post helpful.

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    Re: How to limit a voltage at 14.5V (20A)

    Quote Originally Posted by dick_freebird View Post
    What you want is a DC-DC converter (probably buck/boost,
    or boost capable in some other topology) capable of standing
    off unloaded panel low temp max V, and producing a controlled
    charging voltage. Like, say, a "solar panel charge controller".
    eBay search turns up many (pedigree, is on you).
    The above is good advice, use a purpose designed solar charge controller.

    Different batteries will have a specific charge profile that will give the maximum battery life (discharge/charge cycles). You could use a solar charge controller with a generic charging profile or you can match batteries and charge controllers for maximum battery life.

    Below is an example of a charge profile.



    An advantage of a proper charge controller is that the solar panels can be supplying current. If you panels can deliver 200 watts and your load is only 150 watts then you batteries are not being discharged, this will add life to your batteries.

    Even if you were drawing 300 watts, the panels would provide 200 watts and your batteries would only need to provide 100 watts, again a good thing.

    Again search for solar charge controllers. There is a large amount of information on the net.


    1 members found this post helpful.

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