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Hello,
Brand new here, just purchased a 24v/4000kw powerjack 2021 version (11.1v board). They put 8000kw on it, but my reading indicates I can probably get 2-3kws continuous. It is definitely more barebones than what others have pictured, but I knew that going in. No LCD.
First off, thank you for providing this forum for discussion and knowledge sharing.
I'm planning an off-grid solar solution using as much DC as possible and using my inverter as little as possible. Right now, it is probably better to describe it as a "grid adjacent" as I'm planning to basically build an all-in-one that I can move around as needed. It may power a detached garage with no current power, but I'd like to be able to put it in a van and drive away. It will be an aluminum extrusion box covered with panels housing the inverter, 5.2kw batteries, battery management, solar chargers and usb plugs, AC plugs, etc. Right now I have ten 250w solar panels, feeding into an Electrodacus DMPPT450 + SBMS120. I'm only using the SBMS120 right now. (my initial impression is wildly positive)
It was pretty cool the first time (yesterday) my powerjack was powering my lights, a space heater, a small toaster oven, my fridge, and charging some laptops and phones all at once.
I am almost completely ignorant of oscilloscopes, other than a few youtube videos. My first question may be a how-to on where to place my probes to watch the sine wave coming out without killing myself or my electronics. I have the case off now (yes, know the risks, DANGER).
Some plans I had for simplification/improvements include:
1. maybe remove an LED if present and appropriate
2. maybe put one more loop in one of the wires
3. remove the back panel where 24V battery screw terminals are, and short wires to those posts internally. Attach 2/0 cable directly from my battery to the heatsinks where the positive and negative were connected. This would save space and weight and reduce extraneous connections. I would basically not have the back plate on at all. It would still all be encased in the aluminum extrusion and side panels.
4. learn what needs to be cooled. I think the transformer benefits from constant cooling. I'd also assume the heatsinks areas...
5. learn how close I can safely house my batteries and electronics to the transformer and other inverter electronics. Is it mostly a heat issue, or are there electromagnetic issues I don't understand...
May leave it at that for now. Thanks again.
If it's only a short term observation of the output waveform you might consider a basic hand held battery powered 'scope. This would avoid any possibility of a mistake hooking up the probe and damaging the scope / probe / inverter / yourself. If you want to use a mains powered scope be very careful with how the probe is connected to the inverter's output. A typical mains powered scope will have the 'ground' side of the probe tied to mains earth which in turn is tied to neutral (in most installations). If your inverter's neutral is earthed (it should be for safe operation etc) and you accidentally connected the ground of the scope probe to one of the hots (L1 L2) coming out of the inverter things are not going to go well. All metalic parts of the scope / probes should be treated with caution.
An often overlooked and cheap solution to the problem of accidentally earthing L1 L2 through the scope it is to an old style mains plug pack / wall wart that produces AC instead of DC. AC plug packs were often used to power dialup modems. In one fell swoop that will guarantee isolation and reduce the voltage you are monitoring with the scope to safe levels. Plug plug-pack into inverter, connect scope probe to plug-pack AC output. The waveform you see will still be a fairly good representation of what comes out of the inverter and actual AC voltage on the inverter can be calculated easily enough if needed.
This sort of thing
I am almost completely ignorant of oscilloscopes, other than a few youtube videos. My first question may be a how-to on where to place my probes to watch the sine wave coming out without killing myself or my electronics.
What make/model oscilloscope do you have?
+1 everything @thebutcher wrote. I actually cut the ground prong off the cords I use on the 'scopes--yes, that's not safe, but as the DSO 'scope power supplies are generally isolated, that solves the issue...
3. remove the back panel where 24V battery screw terminals are, and short wires to those posts internally. Attach 2/0 cable directly from my battery to the heatsinks where the positive and negative were connected. This would save space and weight and reduce extraneous connections. I would basically not have the back plate on at all. It would still all be encased in the aluminum extrusion and side panels.
I don't recommend this. Yes, the internal wiring could spare to be beefed up a bit--but I definitely recommend keeping the original back panel and terminals largely for safety...you may notice that all the negative wires go between the heatsinks. And said heatsinks are the transformer output as well--in other words, if the negative wires are getting moved all over, there's a chance the insulation could get worn through, causing a catastrophic failure.
You also DEFINITELY want a disconnect between the inverter and the battery. Personally, I prefer a breaker (though some people like fuses)...simply because if it trips, you can "re-use" it. Not to mention the ease of disconnecting power whenever desired. The inverters do not have any fusing/safety protection on the DC input...apart from everything blowing out.
At 24v, you can use just about any generic breaker (Chinese / eBay or otherwise); for much past 30v, you will need a breaker that's specifically rated for the necessary DC voltage.
4. learn what needs to be cooled. I think the transformer benefits from constant cooling. I'd also assume the heatsinks areas...
Yes, the transformer cooling can always be improved. Unfortunately it doesn't significantly increase the max output before overheating--but it'll definitely help.
PJ inverters...yes, cooling on the FETs won't hurt.
5. learn how close I can safely house my batteries and electronics to the transformer and other inverter electronics. Is it mostly a heat issue, or are there electromagnetic issues I don't understand...
I don't expect any issues with close proximity to the inverter--especially if the original chassis is fully intact (an RF shield of sorts). Yes, the inverters do have the possibility of being a broad-spectrum RF interference generators--but my (PJ 9k chassis) inverter is mounted literally 6 inches above my LFP battery bank...haven't had any issues.
1. maybe remove an LED if present and appropriate
Ah, on the control board...yeah, you could. Definitely quiets the transformer down a bit.
On an 11.1V PJ control board, the LED is still present (LED4 right above the LM339 [U02]).
Thanks for the detailed responses.
I have a Fnirsi 1013D Type 2 which is a battery powered portable "tablet" oscilloscope. That may eliminate several of the more dangerous safety concerns?
For #3 I left some details out on the setup, and your concerns I agree with. While testing I have the positive 2/0 battery cable connecting to a shunt (positive side on the electrodacus setup) which connects to a GJ1 65v 200a breaker, which connects to the two short wires connecting to the heatsink of the inverter. Thanks for the concern! Not having a way to disconnect would be trouble. I agree, I like breakers over fuses in this case.
I also briefly considered mounting the one screw end of the breaker directly to the heatsink, but it doesn't save much space to lose those two short wires and keeping the breaker and heatsink physically separated seem like a good idea for temperature reasons (not to mention the breaker could physically rip the heatsink off if bumped improperly, etc).
I also agree and will probably 3d print (nonflammable/meltable stuff) some cable holders and such at some point to avoid any potential for rubbing/wearing of insulation.
I probably will also heavily modify the back plate as well. I may try to do a proper AC breaker and a small box of outlets.
Thanks again.