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All right guys, quick video tonight i want to talk to you about free charge, pre-charging the caps on your pretty much anything i mean anything that has a bank of capacitors, like your inverters or all kinds of equipment. Has that right? So when you plug in stuff that has capacitors there's a spark now, sometimes if it's like a little device, it's a little spark. But when you're talking about like a huge system like this, this is 4 000 watts of uh inverters. I'm gon na put four kilowatt hours worth of battery right with big, connectors and stuff.

That spark right here. If i just connect that in here, this is gon na be a huge spark and what happens is that you could damage your connectors here, because that spark is gon na, be so big that it might melt the contacts and then they're not gon na work as Good, so you do that a few times and then you ruin your connector. So what you have to do is you have to pre-charge your caps on your thing. How do you do that? Let me show you all right here we go.

These four inverters are connected in parallel right and then they terminate into this plug here. This other plug here is the one that's coming off of the battery this battery. Here, it's at 41 volts right this. This all these batteries here can put out five amps each.

So they add up, there's like uh 24 25 of these in here or something so you do the math there's quite a bit of power that can come in here and then they're fused into these big giant fuses. Each one is 80 amps. So, theoretically, this could do about 160 amps for a few seconds right before these uh uh fuses will go right. So there's a lot of power here that are capable right.

So so here's how we're gon na pre-charge the caps here i have connected on this side. A power supply this power supply is set to the same voltage as those batteries right there, and so, as you will see here on the little meter on the power supply in a few seconds, the caps will get there. So what you want to do is you want to set your power supply to the right voltage and to the right uh current. So i have it set to zero right now, the current right and then you want to connect it and then only once everything is connected.

Then you could apply power to the power supply, so we're gon na do that right now. We're gon na do the thing here: okay, so there we go right now it's at zero everything's at zero, because i turn this off right. So now, what i'm gon na do is i'm gon na start applying current and there we go. It's like one amp and it's going and boom just like that in a few seconds.

The caps over there now are at 41.7 volts 41.7. So now those caps right here are charged with the electricity right and so now, when you connect that plug to that plug. There's not going to be a huge differential, and that means that then there's not going to be a huge spark, so let's try it and see and do it in camera. I always flinch when i do these connections because i don't like sparks right.

I don't like sparks um period, but i don't like sparks when they're, not okay, positive, to positive negative to negative okay! Oh now, are you telling me these are different. These are different. Okay, i'm gon na have to change the plugs here, so these are different brands. Uh, that's the thing we keep getting from different suppliers.

They keep sending them different and there's slight differences on these okay. Let me change that and then we'll come back all right, we're back now. Now these two connectors are the same. Should work - oh, my god, okay yeah, so it was nothing, no spark! Why? Because both connectors have the same voltage right so now what you can do is you can disconnect this in here uh, because that served this purpose.

So now you can turn it off, and now we continue with our test. So that's just one way that you can do pre-charge right. You use a variable, voltage power supply and then you charge the caps and then you connect your battery right slowly charge your caps! Another way to do it is to connect the actual battery right, but not connected directly. You use the resistor and there are a couple of other ways, other components that you can use to do that right, but for right now this is the only one i can show you so there you go uh if you were wondering how to do this, how To eliminate those sparks how to not destroy your high current connectors pre-charge, your caps, that's what you have to do all right! Thank you for watching this video, we'll see you guys in the next one bye,.


15 thoughts on “Pre Charging your inverters Caps – No Sparks”
  1. Avataaar/Circle Created with python_avatars Uncontrollable Dogs says:

    I don't like sparks either. Especially @48 volts.
    A simple resistor with a momentary switch in parallel with the main switch works great.

  2. Avataaar/Circle Created with python_avatars Leo Zalewski says:

    Us a DC circuit breaker as it can take the spark, also provides a fast over current trip, the fuses are slow blowing.
    Also use a low current circuit breaker (1A) with a series resistor for 0.1amp to pre charge with a 240ohm 5 watt resistor.

  3. Avataaar/Circle Created with python_avatars hi-tech-guy-18 says:

    I would get a Dual Battery bank DC Rotary Selection Switch
    Add A Resistor or String Series 12V incandescent Car Lamps to bank 2 Side of the Switch

    When you First Connect you Rotate the switch to Bank 2 to Pre pilot – Precharge the caps ((if you using incandescent it will let you know when the caps are ready by going Dim or Off – note just very bright in cap Charging ))
    then you know to switch to Bank 1 for main Direct DC Run

    Other notes this Does Not work With LEDs (it will just eat them alive Due to the Zero impedance of caps Temp want 5000A)

    Other Circuits -> Thyristor triac (self limiting) – Thyristor Heating Element (self limiting) – DC DC Regulator Converter With Self Limiting – latching DC Latching Relay / Switching DC Contactor with memory – RC / Ebike / EV ESC Speed controller (PWM) – or mosfet (PWM) or variable-voltage/variable-frequency (VVVF) drive

  4. Avataaar/Circle Created with python_avatars The Tired Horizon says:

    Surely those grid-tie inverters precharge if you flick on the mains first? Seems to be what was recommended in my Ecoworthy version of that inverter (1000w version). I used a resister to be on the safe side anyway.

  5. Avataaar/Circle Created with python_avatars onjoFilms says:

    In a surge of current, capacitors look like a short. If you add a Choke inline that Choke looks like a huge resistor to fast current. Then as the caps charge, the Choke is basically a wire now. Chokes are basically a coil of wire, sometimes with an iron core.

  6. Avataaar/Circle Created with python_avatars wd9dau says:

    Worked with 3 phase drives and they all had resistor based precgarge circuits. I wonder why the inverter manufacturers don’t do the same.

  7. Avataaar/Circle Created with python_avatars jayzo_sayers says:

    Would this not be simpler by wiring a breaker switch to disconnect the battery from its Anderson connector?

    Also that Jigo is clearly counterfeit, the colour of anderson connectors denote a different keying and I'm pretty sure the Jigo is just a grey connector keying but for some reason blue plastic.

  8. Avataaar/Circle Created with python_avatars Misuta Suparkoro says:

    OH NO are you serious the JIGO connector didn't work, after the emails I sent you about it? My man, I was trying to point this out to you months ago.

  9. Avataaar/Circle Created with python_avatars Kamen Tabakov says:

    What type of resistor should I choose when I want to connect my ebike battery? It's not a big spark but my connector gets burned and maybe eventually won't be able to get a good connection. So I want to implement some type of precharge.

  10. Avataaar/Circle Created with python_avatars RBUG says:

    Usually I precharge my inverter by connecting a 30ohm 10W ceramic capacitor from the positive lead of my battery to the positive input of my inverter.

  11. Avataaar/Circle Created with python_avatars RV Sparky says:

    Funny how pre-charging inverters, amps, items with caps is often promoted but then everyone puts large dissconnect switches inline and of course no precharge ever happens.

  12. Avataaar/Circle Created with python_avatars CET675 says:

    I am such a dom dom. I didn't realize I can charge batteries (okai wall) through the discharge cable. I have been trying to figure out for weeks.

  13. Avataaar/Circle Created with python_avatars DIY with Batteries says:

    You can use a soft starter Sir but it can't handle the 4kwh pack until we connect them in Parallel just like the inverters 😉

  14. Avataaar/Circle Created with python_avatars ruhoer eoijre says:

    Actually, cheapest hi power "resistors" are car bulbs.
    But in a good device precharge circut supposed to be already implemented inside of device.

  15. Avataaar/Circle Created with python_avatars DSK Studio's says:

    You are Not having an A/C Power, Then it's not working I think. | But using Some kind of High power Switch for it. It Better or not?

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