Pre-charge capacitors





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  1. #1
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    Default Pre-charge capacitors

    I read an installation manual today where it is recommended that when first connecting a battery to an inverter, one uses an inline 100ohm resistor to "pre-charge the capacitors"

    Why is this required, is it best practise, "old" way of doing things or maybe a really anal installer requirement?

  2. #2
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    Default Re: Pre-charge capacitors

    My 1kW Microcare has that built in. Before moving breaker to on, push a button and hold till beep, then switch on power. Charges capacitor, says so in manual
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    Default Re: Pre-charge capacitors

    It prevents an initial heavy inrush of current from the battery/ies to the caps.


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    Default Re: Pre-charge capacitors

    My MLT got the same setup where you precharge the unit before closing the fuses.

    It prevents arcing of closing of the fuses and in rush of current to the Caps.
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    Default Re: Pre-charge capacitors

    ...and so does my 10kW MicroCare invertor.
    Quote Originally Posted by Prof View Post
    My 1kW Microcare has that built in. Before moving breaker to on, push a button and hold till beep, then switch on power. Charges capacitor, says so in manual

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    Default Re: Pre-charge capacitors

    En moet nie proebeer fuse toe maak sonder om te pre charge nie. Ohhhoooohhooooo pappa!!! Hy brand gat in die fuse soos hy arc!!!

  7. #7
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    Default Re: Pre-charge capacitors

    How exactly does one do this, any tips?

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    Default Re: Pre-charge capacitors

    Here is n small video how to do it. https://youtu.be/ZlrtmJRfSP8

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    Default Re: Pre-charge capacitors

    Quote Originally Posted by NewLandy View Post
    How exactly does one do this, any tips?
    Instead of trying to find a resistor, just use a car headlight bulb.
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  12. #10
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by Fluffy View Post
    Instead of trying to find a resistor, just use a car headlight bulb.
    It's a 48V battery.....Car lamps are 12V....

    Where on earth can I get a resistor in SA.
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    Last edited by NewLandy; 2020/07/11 at 12:28 PM.

  13. #11
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by NewLandy View Post
    It's a 48V battery.....Car lamps are 12V....

    Where on earth can I get a resistor in SA.
    Mantech and Communica. You can get ones they use in audio crossovers.

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  15. #12
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by NewLandy View Post
    It's a 48V battery.....Car lamps are 12V....

    Where on earth can I get a resistor in SA.
    Use a regular kitchen kettle. It takes a minute longer, but the switch of the kettle comes in handy.

  16. #13
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by Gerlach View Post
    En moet nie proebeer fuse toe maak sonder om te pre charge nie. Ohhhoooohhooooo pappa!!! Hy brand gat in die fuse soos hy arc!!!


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  17. #14
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by bigboy529 View Post
    En moontlik ook agter in jou onderbroek soos jy skrik.
    hahahahaha!!!! ja, ek was skoon in gedagte gewees en so vergeet ek om te pre-charge te druk. hy klap daai 22x58 fuse sommer n lekker hap in. Ek het destyds vinnig geleer met die 48v systems en hoe amps speel jy nie. Met 96v dc system $%^& jy nie me rond nie. Hy vernader vinnig jou tools in gesmelte metaal.

    Ek sal nooit vergeet nie. Ek was eendag gou deur saam met ouens na n site toe vir nood geval van hoŽ spanning transformer change over langs die N1. 400MW. Die grond bewe onder jou soos die tranfromers sing. Ouens was besig om die change over switch kamer te verf. So klim die een ou bo op die change over kas met die verf om die dak te verf en so skop hy die emmer verf om en dit hardloop binne in. Stel dit so, ons het 10mm stainless steal bolts op getel wat half weg gesmelt was en gate deur 5mm plate gebrand is.

  18. #15
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by Gerlach View Post
    Mantech and Communica. You can get ones they use in audio crossovers.
    These are freely available and no need to fork out 10 times the price just because it is in a piece of aluminium. Inside heat shrink is fit for purpose.
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  19. #16
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by Gerlach View Post
    hahahahaha!!!! ja, ek was skoon in gedagte gewees en so vergeet ek om te pre-charge te druk. hy klap daai 22x58 fuse sommer n lekker hap in. Ek het destyds vinnig geleer met die 48v systems en hoe amps speel jy nie. Met 96v dc system $%^& jy nie me rond nie. Hy vernader vinnig jou tools in gesmelte metaal.
    Wel so met die tyd sal mens uitvind dis hoekom daar snap action switches en relays gebruik word om stroom te maak en te breek. Nie die fuses wat ons mense gebruik op solar stelsels.

  20. #17
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by ekkekan View Post
    Wel so met die tyd sal mens uitvind dis hoekom daar snap action switches en relays gebruik word om stroom te maak en te breek. Nie die fuses wat ons mense gebruik op solar stelsels.
    Ek neem aan jy praat van High speed circuit breakers en Air breaker, soos wat ABB maak. Freedom Won en AESS gebruik die ABB se breaker wat motorized toe klap.

    Bluenova gebruik ook n Precharge in hulle system wat die Magnetic Contactor Solenoid toe maak, en hulle het n paar groot units wat hulle bou.

    Ek dink met tyd begin almal nou aan pas met sekere goed maar baie high amp plants installes gebruik nog maar fuse bases. Ons kan in baie detail in gaan oor breakers en fuses en stuff oor arching en so aan maar ja. Elke een doen sy werk.

  21. #18
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    Default Re: Pre-charge capacitors

    I bought one online from Mantech, R26.00, Al clad, very pretty looking..

    The postage was R100.....Worth it and saved me trying to explain to my wife that we need it and she has to drive to PTA and back again to fetch it.

    Couriers have saved my marriage on many an occasion!

  22. #19
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    Default Re: Pre-charge capacitors

    Quote Originally Posted by NewLandy View Post
    I bought one online from Mantech, R26.00, Al clad, very pretty looking..

    The postage was R100.....Worth it and saved me trying to explain to my wife that we need it and she has to drive to PTA and back again to fetch it.

    Couriers have saved my marriage on many an occasion!
    Nice man!! bly jy het reg gekom daar. Mantech maak ons mal in die kaap met orders. Hulle hele system is demekaar tans en die sales mense is vrek ly jong!!!!!! Vriend van my sukkel al 3 weke lank met hulle met order wat hulle rond geneek het met 2 x 48v 8amp chargers. Een het gekom maar hulle het nie ander een gestuur nie, of erins tussen al hulle goed. Ons wil dit gebruik om 100 amp mppt te backup met 5kw inverter of n reen dag. Dan hoef die inwerter nie te koppel aan die grid om te charge nie, die 2 chargers sal daai werk doen. Die city kan niks aan jou maak met daai nie. Microcare het klaar so unit gebou.

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