diy solar

diy solar

Help with 128 batteries each one is 280ah, and want to configure for 48v system.

Most of the time, energy independence come with an other way of consuming this energy.
Lean how to use less, 100kwh of batteries is a lot....
I have already reduced it by about 400kwh + monthly but due to our home job there are extenuating circumstances that are out of the ability to control.

 
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Went through all the information and yt videos and decided to place the order for 9 Chargery bms systems, wanted to have an extra on hand. After reading over them all Batrium still seems super nice but the chargery is much less overall and seems very easy to work with.
Why 8 times 280Ah 48V batteries instead of just one 2240Ah 48V battery?
For me it seem a lot easier to connect 8 cells in parallel to create one big 2240Ah cell and connect those in 16S battery.
After you need a cheap, but super nice, Zeva 16S bms and a large 500A contactor. That it, no?
 
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Why 8 times 280Ah 48V batteries instead of just one 2240Ah 48V battery?
For me it seem a lot easier to connect 8 cells in parallel to create one big 2240Ah cell and connect those in 16S battery.
After you need a cheap, but super nice, Zeva 16S bms and a large 500A contactor. That it, no?
I had looked at that but many responded that 16s by 8 would be easier to manage and monitor.
 
To me it easier to manage only one battery instead of 8 or, preferably, manage only 16 cells and one BMS instead of 128 cells and 8 BMS.
Well, I can only see one advantage to have 8 BMS and it's about the balancing current capability who will be 8 times higher.
But despite if the BMS balancing current isn't large enough, still you can manually balance the 16 cells (2240Ah) manually once a month, a year or a decade (depend of the quality of the cells).
Or ask at the BMS supplier how you can add external balancing capacity to their BMS... yes, it's a bit of work/trouble.
 
Personally I'd do 2P16S4P (i.e. 4 packs in parallel, each pack being 16 in series of 2 cells in parallel). It should be the best compromise between a lot of packs/BMS and one giant pack with only one BMS ;)
 
I have already reduced it by about 400kwh + monthly but due to our home job there are extenuating circumstances that are out of the ability to control.

Wow...1800kwh a month...? That's what I use in a year...?
But 400wh a month, a 20% decrease is already quite nice..!
 
Why 8 times 280Ah 48V batteries instead of just one 2240Ah 48V battery?
For me it seem a lot easier to connect 8 cells in parallel to create one big 2240Ah cell and connect those in 16S battery.
After you need a cheap, but super nice, Zeva 16S bms and a large 500A contactor. That it, no?
And now you got a fail on one cell..you got no spare...what do you do...you dismantle all pack..? In the 8p16s you just disconnect one pack (the one With the faulty cell) and you got time to fix the problem, you can disconnect a pack to top balance it if needed...it's flexible.
You could even sell one (16s pack)...or buy a new one and add it... I feel it's far easier to manage.
 
And now you got a fail on one cell..you got no spare...what do you do...you dismantle all pack..?
Simple. You identify the faulty 2240Ah cell, after you identify and remove the single 280Ah faulty cells and continue to operate your 48v 1960Ah battery for the time you shout your cell supplier to had sold you crappy cell ;)
After you add a new 280Ah cell and you will be able to operate your 48v 2240Ah battery.
In my case, I have more confident in cells than in electronic BMS. So, to me, less fairly reliable BMS and more ultra reliable busbar is the way to go.

The downside of a single battery is you have to stop your system to play with. If this is really problematic, build two 1120Ah batterie could be a good option.
 
Splitting the entire thing into two packs sounds pretty smart to me, that way as long as only one cell fails at a time it would be possible to stay online, if needed.
 
Simple. You identify the faulty 2240Ah cell, after you identify and remove the single 280Ah faulty cells and continue to operate your 48v 1960Ah battery for the time you shout your cell supplier to had sold you crappy cell ;)
After you add a new 280Ah cell and you will be able to operate your 48v 2240Ah battery.

So you need to cut all charge/discharge twice, it's rather inconvenient. If you have multiple packs you can repair the faulty one while continuing to use the remaining ones ;)


In my case, I have more confident in cells than in electronic BMS. So, to me, less fairly reliable BMS and more ultra reliable busbar is the way to go.

Then you would want the redundancy of multiple packs. With one big pack if your only BMS fails then the whole system is down. Having no SPoF plays a big role in having a high availability.
 
Wow...1800kwh a month...? That's what I use in a year...?
But 400wh a month, a 20% decrease is already quite nice..!
We take care of Intellectually disable people that do not have family or homes, and they do not understand many of the normal energy saving ideas. And by law we have to leave if we loose power for more than a day to a hotel which is extremely tiring, so we are taking steps to keep the power on and save on monthly costs. I need to take a few pictures just removed the ballasts and floruenscents from all the lights and put in led in the basement and kichetchen, laundry areas. Probably will not add to much but everything will help.
 
So you need to cut all charge/discharge twice, it's rather inconvenient. If you have multiple packs you can repair the faulty one while continuing to use the remaining ones ;)
Yes, but with multiple packs, you have to consider the not negligible fact that you will have to balance the batteries before put them back parallel (all batteries at similar voltage, if no there will have big current flow).
Also, this imply more contactors (or at least kill switchs), more lugs, crimps, wires... so more chance of trouble.
Flexibility have a cost and it's often at the cost of reliability.
I'm a big fan of keep it simple stupid solutions with no extra components, but I understand some people can prefer flexibility... but never from 8 battery+8 bms.
Then you would want the redundancy of multiple packs. With one big pack if your only BMS fails then the whole system is down. Having no SPoF plays a big role in having a high availability.
If I have to do a single large (100 kWh and +) battery like that with only 16 large cells (2240Ah) I think it's would not be a crazy idea to have two identical BMS with the master driving the show and the second bms simply waiting to replace the master in case of fail.
 
Yes, but with multiple packs, you have to consider the not negligible fact that you will have to balance the batteries before put them back parallel (all batteries at similar voltage, if no there will have big current flow).

true, but you can just wait the right moment to add the repaired pack back. And you have the same problem at the cell level with one big pack anyway.


Also, this imply more contactors (or at least kill switchs), more lugs, crimps, wires... so more chance of trouble.
Flexibility have a cost and it's often at the cost of reliability.

Actually if each independent pack has the same complexity as the one pack solution (let's say cells + BMS + fuse + disconnect for example) the end result will be more reliable, even if the total number of parts is higher.


but never from 8 battery+8 bms.

Yes, 8 is a bit too much, that's why I was suggesting 4 ;)


If I have to do a single large (100 kWh and +) battery like that with only 16 large cells (2240Ah) I think it's would not be a crazy idea to have two identical BMS with the master driving the show and the second bms simply waiting to replace the master in case of fail.

Why not, it would work, but then you'd better having 2 separate packs instead of one at this point ;)
 
Actually if each independent pack has the same complexity as the one pack solution (let's say cells + BMS + fuse + disconnect for example) the end result will be more reliable, even if the total number of parts is higher.
Still it's easier to build, manage and monitor fewer components, contacts and crimps.
To me, in the specific case of 128 cells to build a 48V battery or batteries, my choice is one 16S 8P battery. I can understand to use two 16S 4P batteries, but more batteries, I don't.

Well, the important here is we had explain some reasons to choose how to connect large group of cells with some advantage and disadvantage.
Now kromc5, or others reader, can choose their preferred battery configuration based on those reasons.
 
Well, the important here is we had explain some reasons to choose how to connect large group of cells with some advantage and disadvantage.
Now kromc5, or others reader, can choose their preferred battery configuration based on those reasons.

Yep, exactly ;)
 
We take care of Intellectually disable people that do not have family or homes, and they do not understand many of the normal energy saving ideas. And by law we have to leave if we loose power for more than a day to a hotel which is extremely tiring, so we are taking steps to keep the power on and save on monthly costs. I need to take a few pictures just removed the ballasts and floruenscents from all the lights and put in led in the basement and kichetchen, laundry areas. Probably will not add to much but everything will help.
Timers on corridors lights, on tv set and all those things, forcing them to get up and "add" some more time to this device that will finally shutdown automatically..? Well, first analysing where the energy is going then actions should be easier.
This is a kind of work that can be hard on nerve, and very exhausting...but I suppose also very rewarding.
Nice job.
 
Yes, but with multiple packs, you have to consider the not negligible fact that you will have to balance the batteries before put them back parallel (all batteries at similar voltage, if no there will have big current flow).
Also, this imply more contactors (or at least kill switchs), more lugs, crimps, wires... so more chance of trouble.
Flexibility have a cost and it's often at the cost of reliability.
I'm a big fan of keep it simple stupid solutions with no extra components, but I understand some people can prefer flexibility... but never from 8 battery+8 bms.

If I have to do a single large (100 kWh and +) battery like that with only 16 large cells (2240Ah) I think it's would not be a crazy idea to have two identical BMS with the master driving the show and the second bms simply waiting to replace the master in case of fail.
Perhaps I'm wrong, but I would say that as soon as your repaired pack is topbalanced, you could put it in parallel, just program the bms for a low discharge rate like 10A.. and the pack should go down to those others pack.
 
1 cell fail expected -> 2 packs maybe?
2 cell fail expected -> 3 packs maybe?

my personal preference is for per cell voltage monitor and balance lead, but this result in more BMS/complexity at your large scale.

thank you for trying to address the electricity needs, i am sure your efforts will result in a victory
 
Allow me to clarify what I am trying to point out.

We use our batteries to “supply” us with power. As an example let’s use a 48v battery, 16 cells at 3v each.

At 100 amps that “supplies” 4800 watts.

Each individual cell supplies 300 watts.

So each cell is responsible for 1/16 th of the power supplied.

So is this the correct answer because it seems to be going back and forth. I would have thought it is the way you state it here...each cell supplying SOME of the load to make the total load up from the pack as a whole.

But others here keep saying ....NO.....each cell will supply 100 amps. So its hard for a new comer to grasp. Which point of view to take as correct ?
 
Each cell supplies 3 V @ 100 A --> 300 W, the whole pack supplies 48 V @ 100 A --> 4.8 kW.

Each cell has 100 A passing in it.

Power is different than current, and current is different than voltage.
 
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