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That's a bummer it will put a hard limit on the amount of continuous amps
You say with a lathe can make your copper bolts and then replace the brass in your new GS 6kw 12vdc .
Okay thinking about this, from what I understand this is only an issue on the new 6K the from re-reading the posts on the 12K it sounds like it is solid pad with a connection on both sides so increased resistance is minimal if we are talking 4mm that small amount of added resistance won't be a problem its like adding a thick washer under a connection.
The 6K is a bar that connects on the outside and then that connection would be a few inches long and then connects to a copper bus bar on the inside. I am hoping that these are actually nickle coated copper bars. Although swapping in new bars into these would be simple, so maybe something that can be done at the factory since they are bending copper bars for inside.
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11 minutes ago, dickson said:You say with a lathe can make your copper bolts and then replace the brass in your new GS 6kw 12vdc .
Yep, I can make new ones so not really worried about it. I would hate to open the case, and won't unless I have documented the terminal overheating and video the process I don't want to risk loosing the warranty right away. I will prep and make sure I have a few small pieces of different sizes copper stock on hand. The local supply house has some off cuts that I like to pick through for projects but you pay per pound and its not cheap right now. I only have 1/4" X 2" copper bar and some 1.25" round bar stock right now. Off subject you can get 3/4" grounding rod for a decent price at the electrical supply nice for small projects.
Brass is still a very good conductor. Almost everything looks like a poor conductor when you compare it to copper.
The ability to resist losing contact with the wires terminated to it is far more important than the losses in the terminal itself. Brass should serve you well in that regard.
8 hours ago, AquaticsLive said:That's a bummer it will put a hard limit on the amount of continuous amps it can handle before the plastic housing of the terminals gets discolored/brittle and the heat cycling will cause the hardware to loosen as well. What type of plastic is being used?
They have about 50% of the capacity of the aluminum PJ terminals before overheating.
Just did some math...the PJ terminals (after I pulled all the hardware off of them) I do agree are aluminum. Just way too light to be steel...
But they have a 10mm diameter = 78.5mm2 cross-sectional current carrying area.
The new GS terminals for the 12kw have a 20mm diameter = 314mm2 cross-sectional current carrying area. This is FOUR TIMES the current carrying area--meaning that even if the electrical resistance of the brass terminals is DOUBLE that of a PJ terminal (which mathematically I would be surprised if it is), a single GS terminal will still be TWICE as good as an aluminum PJ terminal.
The "hard limit" that would keep me awake at night has nothing to do with the battery terminals, busbars, or even the PCBs.
Those little TO-220 package leads on the FETs have to carry ALL of the power. Said tinned copper leads measure 0.5 x 0.8mm in size (I have a digital calipers), or 0.4mm2. On a 6kw, there's 12 of those little leads that ALL of the power flows through...twice (high side/low side). So 0.4mm2 * 12 leads = 4.8mm2 to handle 600A continuous. (And that's actually HALF the package rating, or 50A/package--a TO-220 package is rated at 100A continuous, regardless of the actual FET rating...which in our case is 180A.)
yeah, that's what concerns me, not the terminals with 314mm2 cross-sectional area...
single GS terminal will still be TWICE as good as an aluminum PJ terminal
Are we talking about the same terminals as the picture I sent?
That would be exactly what it would need to be for a 6K 12V inverter at least. One single PJ terminal is not even close to being able to handle the amperage. One PJ can only handle about 150 amps safely from my extensive testing of using them for years. The PJ engineer skimped on it with only two per side 4 total. So if the new GS 6K are double of the PJ terminal capacity then they will be the exactly the same as my current 8K PJ on safe current capacity. If that measurement of a 6K terminal is 4 times the volume of a single PJ.
Those little TO-220 package leads on the FETs have to carry ALL of the power.
Yeah that is inside the inverter and although they may fail, there is much less risk of them causing a fire or burning someone, the battery terminals are on the outside of the inverter will for sure cause a fire if they fail or harm the user if they get too close if they are hot. Its one of those safety things for inside of the cabinet versus outside.
The new GS terminals for the 12kw have a 20mm diameter
Re-reading your post yeah I agree the 12K is good, well I said that earlier, the issue currently is the 6K 12V, and hoping that those ones I sent in the picture are not actually brass like the 12K.
August 26, 2022:
FINALLY was able to OK the prototype unit for shipping. Not quite the 'one week' we were initially told, but...!
You can see the "flat head" screws used for holding the case together...they look a LOT nicer than the "army tank" big bulky head screws used before.
We should get the prototype inverters in about a week.
I'm also testing a revised MOS board design...got the boards of that yesterday, so now need to put them together in a test setup and see if they work as intended. That Miller capacitance is such a doozy of a challenge to deal with!
August 30, 2022
- Tracking on the 12kw inverter and 6kw inverter shell packages indicate that they have landed in New York at the SF Express "partner location." This is very good news, they may get to me by the end of the week.
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We have NOT started the production run at the factory yet:
- need to sort out the busbar not fitting issue, see if it's on my end...or if the factory didn't bend the chassis right
- working to test the updated MOS board design, but need a GS-spec mainboard to test them on.
- making a GS-spec mainboard is a bit slow when I have to cut down PJ heatsinks by hand with a hacksaw, then drill and tap the GS-spec holes in them. Slower yet when I get the bolt pattern exactly upside-down on one of the 3 heatsinks...and then have to do it again correctly...oops 😉.
- did a quick check with a 'scope on a GS6 inverter: if the updated MOS board design solves the Miller spike, it's also going on the 6kw inverter MOS boards. Gonna be a bit harder to fit the circuitry on those tiny boards, but I'll get it done!
On 8/22/2022 at 4:45 PM, Sid Genetry Solar said:I do get a laugh out of people saying, "oh, power jack is going to copy your design, they're going to copy your design...!"
nope, not gonna happen. They are beyond focused on bottom line cost. And us at Genetry......basically aren't. Our goal is to get the cheapest QUALITY parts (i.e. not ridiculous overpaying), and not focus on "the cheapest parts we can find."
I had a bit of back-and-forth between the factory about the caps we're using in the Genetry inverters. Everyone else (including Aims, Sungold, Growatt, etc., etc.) uses a bunch of really tiny--and cheap--caps on the mainboard. The problem is that they're looking to get "microfarads" as the only thing that matters.
It isn't. What actually matters is getting the ESR down. And unfortunately, the only way to get a very low ESR rating on a cap, is to get a physically very large one. (This also significantly increases capacitor longevity due to increased ripple current rating.)
After I insisted on 4-5 lead 40x80mm caps, the factory priced them, and came back with a quotable quote, "those capacitor must be made of gold!"
Funny, very funny 😉. Chance of seeing those caps in a Power Jack inverter from the factory? Empirically 0%.
That's actually not quite right
As each cap ESR will be resistance in parallel the effective ESR will be the rating of the cap divided by the number
Another thing is placing a ceramic cap across the electrolytic one greatly reduces the ripple current on the E cap preventing it's failure
That's actually not quite right
Of course this is the case.
My point is that what actually matters is the ripple current rating. This often directly correlates to the ESR rating, as ESR = heat in the cap, and the lower the better.
EACH cap on the new GS inverters is rated to nearly 8 amps ripple current. Times four = 32 amps ripple current rating. When we're running hundreds of amps of power, this seems only barely adequate--but the competition is all using caps barely rated to 2 amps ripple current (if that).
Another thing is placing a ceramic cap across the electrolytic one greatly reduces the ripple current on the E cap preventing it's failure
Depends on the frequency of said ripple and size of the ceramic cap, of course...but there are two polyester 10uF caps in parallel with the electrolytics as well on the GS mainboards.
Poly caps work well also
September 1st:
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ONE of the 2 packages arrived...it's the 6kw case prototype. This means that I got a good look at the battery terminals. I'm not 100% sure, but wouldn't be surprised if they're at least mostly copper. Took a file to the edge of one of them, and it's got the same reddish color inside as it does on the outside. Compare to an (obviously) brass GS12 terminal and see the diff....
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- not sure where the actual 12kw prototype package is. Will call the carrier in the morning and try to figure out what's going on.
Overall the 6kw shell is pretty decent--most of my complaints with it have to do with where the case was bent (not where I specified, obviously!) which makes the screw holes not line up very well, in addition to making measured distances rather problematic.
Just heard from the factory.
Apparently the 12kw prototype got rejected at the airport security scan...and sent back to the factory.
Now they have to send it back out again via a different carrier...and hope it passes this time.
This is the first time we've ever had this happen--and we've had them send close to a dozen units by airmail with nary an issue.
Ugh. Unexpected delays.
And I am extremely hesitant to "OK" the factory to start the production run without going over the prototype unit and making sure they got everything right. (Especially trying to figure out what's going on with the busbars.)
But this is real life, not a reality show. We at Genetry obviously thank all of those who placed preorders for your patience.
Further discussion with the factory...apparently, the 12kw inverter failed a "magnetic inspection report" at the airport and was returned to the factory as a result.
The only website I can find with regards to this is: https://www.twingsupply.com/faq-air-cargo-magnetic-inspection/
And down at Q8.3, in the long list is....relays.
Guess what: this is the VERY first time that we have had the factory ship a Rev. C control board--which has 2 large latching relays. These relays have very strong internal magnets to "hold" the state with no power.
So I ran the "Sensors Multitool" app on my phone, and brought it close to a Rev. C control board. My phone didn't notice much until I got within a few inches of said relays--but boy did it go haywire when I got within an inch!
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Who would've guessed........