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207kWh System... In 12V??? 😬

Yup
Looks like about 20 equalizers should take care of it. lol

Or you could simply cut out the problem during the design phase and use 48V batteries of course 😎. As everyone has suggested.

Before everyone comes up with a million more ways to solve this problem let’s just agree :

1. It shouldn’t exist in the first place.

2. BattleBorne should be ashamed of this crap.

Just stay in your lane in the 12V market or produce a proper 48V battery. This does nothing to help folks wanting a proper off grid system IMHO. It likely does more harm than good for people new to the idea.
 
IF you could somehow connect all of the BMSs together so they talk to each other and work as one
This wouldn't solve the problem. As they wouldn’t be able to transfer balance current between them.
 
Reasons to do the large ESS in 12v = 0
Reasons to Not do the large ESS in 12v = 3 (cost, balance, maintenance)

Maybe the 12v were just for the vid, and swapped out for 48v once the camera crew left!
 
This wouldn't solve the problem. As they wouldn’t be able to transfer balance current between them.
Well, imagine since I said, "IF you could somehow connect all of the BMSs together so they talk to each other and work as one," that means they would actually work as a single BMS.
 
Well, imagine since I said, "IF you could somehow connect all of the BMSs together so they talk to each other and work as one," that means they would actually work as a single BMS.
But, it wouldn't work. Unless there were also balance wires between the batteries. The reason why they get out of balance is because there is no balancing between them.
 
But, it wouldn't work. Unless there were also balance wires between the batteries. The reason why they get out of balance is because there is no balancing between them.
I mean, if we are designing a system to solve this problem, it would have the ability to do exactly that, no? I said IF. :unsure: Stop thinking about what existing systems can do.
 
I was just kidding. I picked up 4 tornado damaged MT Solar mounts for $4K used. https://diysolarforum.com/threads/sinclair-or-mt-solar.76590/

As these were used, they don't qualify for the solar tax credit but this is for my shop so I get to depreciate them fully out, I won't be claiming a credit. My first MT Solar mount was about $6800 during covid with freight to the terminal.

This is the aerial before the tornado hit the used array I purchased. Broke all 4 adjusters, the mounts are rated at 105 mph but the tornado had 150 mph winds.

View attachment 210357

And this was the small array after the adjuster broke. One would have thought the panels would have sustained more damage. This will become a 10 panel array, 3x3 with one odd panel at the top. I don't see doing 2x5 and I'd have to extend the rails to mount wider panels.

View attachment 210358

Previous owner told me the poles bent over on the larger arrays. I thought maybe the 5 rows of panels might be too high and was thinking I might go to just 4 rows high but in the end I decided to make a double pole mount with 4 columns and 5 rows high. I do have to add extensions to the rails as these had 250W panels which were slightly narrower than the 370W NE Solar panels. My space for this array is limited for length, thus the decision to go 5 rows high.

I think having 3 columns x 5 rows was too much for a single pole. With 4x5 and 2 poles this should work out well. Plan is 21 panels total. One odd panel way at the top, strings will be 7S.

I was planning on Sinclair this time but they dragged their feet and the used MT mounts came up for sale and couldn't pass them up. I did order 2 adjusters, he did have one new adjuster he gave me. I'll still have enough parts left over for one more array.
This is a really neat setup, especially with bifacial for the sonw to beam in from all angles. But if we calculate with a large sized panel of 1300x2400 it will be an insane power at the shaft/Beam If the beam is mounted in strongest direction perpendicular to the panels and the force will be around 100-120kg/sqm. You are looking at a single HEB 600 to manage the wind force with tolerance and without any plastic deformation. What beam is it right now? I have been thinking of building a 10m long fence with bifacial pointing east/west to get some moringin evening power and also extra power during winter when beaming from snow, but I think this is a better idea, with a tower. But the vertical beam need to be very powerful as shown above.
 
That doesnt matter much though, it is the series of the system that is important, otherwise you could say that a LiFePO4 128S is just 3.2V instead of the +400V? As soon as you put the batteries in series you increase voltage and reduce the Amp hence need for thick cables. So I would say that this is a 48V system but as soon as you need over 12kW from the storage (no matter if it is 15kwh or 200kWh) you should consider a HV Hybrid or HV off grid inverter instead of 48V and crank it up to atleast 64SxP to not be forced to use Frankenstein cables, fuses and connectors.
The reason it is very significant is that you're going to balancing issues over time.

Also instead of one BMS failling you now have four.

Instead of one LVD and HVD, you now have 4 in series. If cell drift occurs at all, one of the batteries will disconnect and render that entire string useless.

And no that is not a good comparison because if you have a 128 cells in series, you should have one BMS.
 
This is a really neat setup, especially with bifacial for the sonw to beam in from all angles. But if we calculate with a large sized panel of 1300x2400 it will be an insane power at the shaft/Beam If the beam is mounted in strongest direction perpendicular to the panels and the force will be around 100-120kg/sqm. You are looking at a single HEB 600 to manage the wind force with tolerance and without any plastic deformation. What beam is it right now? I have been thinking of building a 10m long fence with bifacial pointing east/west to get some moringin evening power and also extra power during winter when beaming from snow, but I think this is a better idea, with a tower. But the vertical beam need to be very powerful as shown above.
I'm no mechanical engineer but HEB 600 for panel mount sounds like something gone wrong.
 
I mean, if we are designing a system to solve this problem, it would have the ability to do exactly that, no? I said IF. :unsure: Stop thinking about what existing systems can do.
Yes, it could be done. Each battery would have to be equipped with a 6s BMS. And have external connections for 4 balance wires. Some provision would have to be in place for the beginning battery of each string. That wouldn't be using the #1 balance wire.
Still much better to just buy the correct batteries for a system.
 
I'm no mechanical engineer but HEB 600 for panel mount sounds like something gone wrong.
You can use Euler to calculate it, 150miles per hour give more than 100kg load per square meterso if you have a tower that is 6m high you can iomagine the force if it was only the top row of solar panels, that is 1,2x4,8m = 600kg for just the top row. So now if you think that you take a beam and attach it to a wall so it is going straight out 6m, and at the far end you add a 600kg load it will be quite evident that the beam need to be massive :) if the area on lot is big enough, it will be much more cost and weight efficient to build it out sideways, so it is 3 panels high and 4 panels wide instead. But then the horizontal beams need to be calcualted both for bending around Y axis but also the gravity force from structure and self weight since these "arms" need to go out over 4m on each side.
 
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The reason it is very significant is that you're going to balancing issues over time.

Also instead of one BMS failling you now have four.

Instead of one LVD and HVD, you now have 4 in series. If cell drift occurs at all, one of the batteries will disconnect and render that entire string useless.

And no that is not a good comparison because if you have a 128 cells in series, you should have one BMS.
I agree that the amount of BMS part is excessive, although in the first post I got maybe the wrong assumption that you though it would be a lot of AMPS and inefficient. Regarding the BMS, in HV system, you can have one BMS, but there are no BMS with inbuilt BMU that handle over 24S (that I know of) so usually you still have to have a BMU for each 48V battery and then x amount of BMUs communicate with the BMS. and each Battery module (usually of 48VDC) are then connected i Series. And I still think it is false to call that system a 12VDC system, it would have been a really big difference and a lot worse if all the batteries would have been connected in parallel also. Although it is really bad as it is already, but that would have been insane.
 
You can use Euler to calculate it, 150miles per hour give more than 100kg load per square meterso if you have a tower that is 6m high you can iomagine the force if it was only the top row of solar panels, that is 1,2x4,8m = 600kg for just the top row. So now if you think that you take a beam and attach it to a wall so it is going straight out 6m, and at the far end you add a 600kg load it will be quite evident that the beam need to be massive :) if the area on lot is big enough, it will be much more cost and weight efficient to build it out sideways, so it is 3 panels high and 4 panels wide instead. But then the horizontal beams need to be calcualted both for bending around Y axis but also the gravity force from structure and self weight since these "arms" need to go out over 4m on each side.
600 kg load is a lot but you were talking about frikking HEB 600. You would use something that size to build small bridges for 60 ton semis!
6 m tower built from HEB600 can handle around 320kN wind load at the 6 meter lever arm. 600 kg is only 6 kN

6 meter section of HEB600 alone would weight around 1300kg, that aint fly very far even in windy weather. :ROFLMAO:
 
There should be a way to connect 12V batteries in series to make 48V batteries, or 48V batteries in series to make 480V.
There is, after all, a way to connect 3V cells to make any of those.

If passive balancing (bleed off high cells through resistor), that works in 4s or 16s packs, so could work with multiple 12V or multiple 48V batteries, so long as they communicate and tell fully charged batteries to bleed all cells so the stragglers can catch up.

Active balancing, each cell could feed DC/DC converter that boosts to pack voltage, enabled whenever that cell is too high.
Add a battery balancer to do the same from 12V to 48V, or 48V to 480V.

Similar to having separate battery charger for each and periodically bringing all batteries to same SoC.

Some BMS are modular, with electronics per cell. REC has 16s modules and can connect parallel (for more Ah) or series (for more voltage). They have an active balancer, not sure exactly what they do in the series connected case.

BYD has HV batteries that can be stacked for higher voltage and capacity & wattage, e.g. 2 to 5 battery modules.
Not sure if the control unit simply connects to additional cells, or if there is a master/slave arrangement.

 
600 kg load is a lot but you were talking about frikking HEB 600. You would use something that size to build small bridges for 60 ton semis!
6 m tower built from HEB600 can handle around 320kN wind load at the 6 meter lever arm. 600 kg is only 6 kN

6 meter section of HEB600 alone would weight around 1300kg, that aint fly very far even in windy weather. :ROFLMAO:
Hi, Im not sure about your background but I am a mechanical engineer and have constructed all kind random products for a profession. I'm sorry to say but a HEB600 by itself would never ever be used for a tall bridge :) You usually have either massive towers with wires helping with the support between towers or you use a structure below road surface so the total thickness of the surface below the car is way more than 600mm. I dont have Inventor on this Computer so I didnt do a FEM analysis myself, Ijust calculated with E module as 2.1x10^5 which is common for normal steel and used Eulers case with 1 fixed point and the second free hanging. If you show me your calculation I guess we can see where it has been wrong. But the whole area of the thing blowing with a pressure of +110kg/sqm will be 2.4x2x6x110 = 3200kg and to simplify you can put that as one force on middle of beam = 3m up on the beam. And you can load it some more before plastic deformation occur but not much and the HEB 500 will not handle the +3000kg load. Can you show your calculation and we can compare?
 
There are several.
Batrium is one that comes to mind.

He never called it a 12v system.
He said "12v batteries".
I have good connections within Batrium regarding different projects and they all have multiple BMU in common, when going above 16s, they call the "BMU" Cellmate-K9 and they recommend one of those for each 48VDC pack you want to have in Series. So if you need 8 48VDC, you also need 8 BMU (Cellmate-K9) that each keep track on the 16 individual cells regarding voltage and balancing. You just need to look at the subject of this thread and it is 207kWh in 12V... but it is actually 48VDC, divided to 12V which is divided to 3.2V internally.
 
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