PLEASE NOTE: If you had an account with the previous forum, it has been ported to the new Genetry website!
You will need to reset the password to access the new forum. Click Log In → Forgot Password → enter your username or forum email address → click Email Reset Link.
not a torroidal type transformer core but more like h-type or some call it e-type with the many iron sheets of the core to lessen the eddy currents I think...
E-core is simply much easier to produce, wind, and mount.
Toroidal transformers are much better from an electrical/efficiency standpoint. But they're a LOT harder to wind...and let's just say that mounting the larger ones is quite difficult. Here's one of a dozen websites talking about toroid vs E-core: https://www.miracle.net.in/blog/advantages-using-toroidal-transformer/
Nah, the way you know what's on and off is by looking at the inverter output load.
I watch the latest video and Sean can see the wattage at 9456 watts and he also see the LED flickers and it is normal when his AC turn on . He know what is on by watching the output load . He also watch the input voltage drop to 54 vDC and the light dim and say the battery is loo low and someone need to shut smoething off . My PJ do not have accurate meter so I watch the battery input DC volts to be safe and shutdown the inverter or there will be a fire just like on youtube that is impossible to put out .
so it would be best to keep the battery voltage above 51 volts to aid the generation of the sine wave and with the right amount of filtering it will potentially more closely approximate a PSW (pure sine wave ) and not be a flat topped sine wave.
IT took me a long time to figure out the battery voltage need be above 51 volt and there is nothing I can do to the transformer to change that unless I re-design the transformer . You finally figure that out also .
I get a bit confused when people talk about 'core voltage'. My understanding is that the design (shape) and materials of a given core determine the maximum magnetic flux density (directly related turns per volt) of said core.
In general, toroidal cores have a much higher flux density than E/I cores of similar cross sectional area (CSA).
The higher the flux density (and hence turns per volt) obviously the smaller the number of turns required to achieve any given input/output voltage is. The ratio of turns between primary and secondary does not change.
However obviously lower flux density = more turns per volt = more wire = more resistance = more heat loss in the transformer = lower efficiency (and saturation in the core resulting in flat topped sine wave).
The main issues I see with the PJ transformer are (1) using aluminium wire means higher resistance per turn, which means more heat losses and (2) the turns ratio is wrong so it can't produce a high enough peak voltage under heavy load once losses are accounted for, nor when battery voltage is towards the discharged end of the curve.
oh yes, forgot to mention that the number of turns you can physically fit on any given core is the primary factor determining the maximum power achievevable with any given core. If you had ultra-thin superconducting wire and an extremely high purity core, you could potentially have 10kW from a 10mm2 CSA core!
I believe they said the 30k Sandi high voltage copper wound transformer inverter had an efficiency of 94 percent....
but the Sandi 30k inverter weighs somewhere in the neighborhood of 600 pounds and cost 850 dollars ... it is a low frequency PSW SP inverter and can out put 150 percent for 5-10 seconds.....
likely take 3 of the small 48 volt inverters for about 9000 dollars to do the same.... for comparison.....
i would not want to run Li-ion batteries....especially used ones in my residence or even the thought of the fires that are hard to put out in an outside solar power shed would be a bit scary...
they ((Sandi) and others) can factory assemble large/small scalable high voltage LiFePO4 battery banks that are safe for similar battery investment....still sounds interesting as an alternate....
good vs 4k high amp 12k inverters price wise???
I get a bit confused when people talk about 'core voltage'. My understanding is that the design (shape) and materials of a given core determine the maximum magnetic flux density (directly related turns per volt) of said core.
Well said...well, apart from a bit here and there, hehe 😉.
The main issue is that a hillbilly like me doesn't have books full of equations to convert "magnetic flux" and "core tesla" into what we really need to wind a transformer: "volts per turn." (I also don't have thousands of dollars of test equipment to measure core tesla/flux and all the other fun stuff.) Yes, the official equations technically deal with all the nitty-gritty details--but yet another problem is that the cores we use simply don't have datasheets. (More often than not, if you don't have a datasheet for a core, someone armed with equations will tell you, "you're out of luck, find something with a datasheet.")
Which is why I just cut to the chase, and measure the transformer core hillbilly style...with a variac, AC volt meter, and AC ammeter. Graph the core voltage vs idle current, and find the "peak efficiency" -> volts/turn number, which I guess I've dubbed "core voltage", as it's pretty well constant for a particular core material/dimensions (in the LF inverter usecase, with fixed frequency and rather fixed voltage range).
Yes, aluminum wire has significantly higher resistance (and a slightly higher temperature coefficient) when compared to copper. But it's roughly 1/2 the weight and 1/3rd the cost--financially it does balance out. It's just when improperly handled that there are issues.
The real issue is that the PJ-spec transformers are simply not specced to handle the advertised power rating.
(and saturation in the core resulting in flat topped sine wave).
At least in the case of inverters, flat-topped sine waves result when there isn't enough battery voltage available to "draw" the top of the waveform. (This happens when the SPWM throttle exceeds 100%.)
In my hillbilly tests, I've run inverter transformer cores at double their ideal 'core voltage' rating. Efficiency is horrid, losses are through the roof, transformer is buzzing angrily--but the output waveform is still a sine, and the "core voltage" (turns/volt) does continue to linearly increase.
Though...I do agree that technically if the core saturates to a DC level, I would expect to see the transformer output voltage fall. But you wouldn't get a perfect flat top on the waveform...that happens by CPU design 😉.
Even with that in mind, the transformers WILL pass a square wave surprisingly well. I haven't tested a square wave at core flux saturation though...
they ((Sandi) and others) can factory assemble large/small scalable high voltage LiFePO4 battery banks that are safe for similar battery investment....still sounds interesting as an alternate.
NO DIY battery for 450v DC off-grid inverter system . IT is impossible to make 265 LiFEpO4 connected in series tight and not be loose and start arcing and the fire will destroy all 265 battery . DIY for 48v DC inverter is safe with LiFEpO4 from people on youtube I think .
7 hours ago, dickson said:NO DIY battery for 450v DC off-grid inverter system . IT is impossible to make 265 LiFEpO4 connected in series tight and not be loose and start arcing and the fire will destroy all 265 battery .
I think Mike G was using 72 cell pairs to get the 240 volt dc battery but indicated it was a dangerous build and for similar investment one could buy the factory built LiFePO4 batteries. he suggested the 32kW battery with built in paralleling studs for future expansion...
he (Mike G) has later video with disclaimer suggesting to not build the high voltage battery DIY.....
I think the tesla is around 400 volts but is liquid cooled or something....even tesla is headed toward the LiFePO4 vs the more dangerous Li-Ion batteries... part of it is the chemical/mineral cost >>>to try to make their product for less money but still high quality (the Tesla vehicles and tesla batteries) electric battery demand is high.....vs their ability to supply them...
yes, I have seen a few videos of the spontaneous combustion of Li-Ion batteries that suddenly decided to fail and overheat and fire is caused which is very hard to put out.. scary indeed>>>>not in my house>>>>makes me even think the outside solar power shed which houses the inverters charge controllers and LiFePO4 batteries could/should be placed further from the house.....
the battery (ESS = energy storage system) is the most expensive part of all my solar off-grid builds by far....🤔
he (Mike G) has later video with disclaimer suggesting to not build the high voltage battery DIY.
HIS friend business buiding and everything inside was burn down by battery on mike g youtube . I was soldering laptop lithium-ion in my bedroom and the battery exploded and could have burn the house down . I had shipping damages lithium-ion car battery exploded by thermal runaway while charging and almost burn the garage down . The new 2020 PV code require all powerwall and inverter be outside with disconnect . Mike G say he hired licensed electrician and get permit to follow the PV code and who is the first to admit doing beside engineering 775 . Most youtube video do not folow the PV code and probably do not know there is a code . Buy the pre-built 450v DC system to be safer as rhe battery are welded and less chance of comming loose .
3 hours ago, pilgrimvalley said:I think the tesla is around 400 volts but is liquid cooled or something
A large part of the liquid cooling (and heating!) for electric car batteries is because they push the cells to the absolute limits for "ludicrous acceleration." Lithium batteries also don't like being charged below freezing.
Apart from the freezing temperature restriction, off-grid systems generally won't need any sort of cell cooling--because the charge/discharge rates are usually well below 1C.
11 hours ago, dickson said:NO DIY battery for 450v DC off-grid inverter system . IT is impossible to make 265 LiFEpO4 connected in series tight and not be loose and start arcing and the fire will destroy all 265 battery . DIY for 48v DC inverter is safe with LiFEpO4 from people on youtube I think .
There is always inherent risk with any energy storage system (batteries or otherwise)--because if that energy gets misdirected in any way, "stuff" happens very quickly!
Yes, there's risk with 48v. But not for serious electrocution or long arc.
At 450v, though, you'd better be coming around with a full electrical suit and gloves...and the electrical arcing potential is nothing to laugh at.
he (Mike G) has later video with disclaimer suggesting to not build the high voltage battery DIY.
it never said why his friend (Mike G) building burned down....
but Meritsun also makes 384 volt pre-built batteries....and any other size and voltage powerwall one might want that is UL approved...
engineer 775 always has a licensed electrician on the solar sites....i like his Solar videos....they are put together professionally....
you can not use equipment that is not ul listed and have it connected to feed into the grid legally....for safety that is why they have the national electric code as a guide to prevent fires....
cement board lining and steel enclosures would be an upgrade..
I bought several steel enclosures for the charge controllers....the lifepo4 could stand to be enclosed differently for safety but it is in an outside solar power shed. ....>>>>definitely not interested in ever putting these battery systems in the living quarters the more i learn about them... I put in in the separate building initially to keep away from the curious little ones and other snoopy people... but safety is still the most important thing....
there is definitely a lot of bad YouTube information and one has to research the equipment pros and cons....🤔🤔🤔🤔
At 450v, though, you'd better be coming around with a full electrical suit and gloves...and the electrical arcing potential is nothing to laugh at.
yes they use personal safety equipment as the potential arc flash in high voltage systems....is always a issue....I watched the lineman replace the meter poles and switches and cut the wires from the transformer pole etc...they wore special gloves, coats, and used fiberglass handles etc to isolate from the transformer....a crew of 3 men...
I have installed several AC whole house electric services but never mess with the electrical company connections without a shut off 1st....
I am still leery of battery connections even after assembling 4 high AMP LiFePO4 batteries.... a loose connection was usually the issue, if any....🤔😎😎
the spark makes me put on gloves and glasses on 24 and 48 volt batteries.....🤔
it never said why his friend (Mike G) building burned down. I thought Mike G say it was his friend BATTERY business building that burn down . Mike say he use aluminum bus bar so the connection is tight and is the first one to use aluminum and say copper bus bar come loose . Some of my bus bar are steel and seem to work . I check every battery connection with a infra red thermoneter and it is under 120 degree F . IF 200 degree F then for sure it is loose everytime and the smell of insulation melting .
On 7/1/2022 at 1:58 PM, pilgrimvalley said:the choke or extra windings help to filter the AC input ((( aka ferrite rings))) on the step-up transformer primary??? kind of soften the input voltage a bit??
ferrite just means it is a magnetic ring of some unknown proprietary mixture... a secret formula...
at least it (ring of the choke) will become magnetic once you run AC electricity thru it....
kind of like when the Chinese were selling pet food with a plastic chemical to make it seem like the pet food had high protein (according to tests) and in the end their secret formula poisoned your pets....🤔
chokes are made of either iron, steel, or ferrite according to the engineering mindset YouTube videos...
the transformer humming is caused by the vibrating of the laminated sheets in the easy to assemble and mount h-type /e-type transformers....according to the engineering mindset YouTube videos...
so one really never knows what any of the powerjack manufactured transformer core of a is made of either, let alone the chokes....some supper cheap concoction to same 2 bits...🤣🤣
not like anyone is going to take them apart and find out either...