Loadshedding affordable battery setup?

Many like to comment with no real world experience of imbalance in cells

It's too soon to have good data on that so my opinion is just that based on my experience and what i have seen what
Batteries behave like with imbalance

And then use logic to say
If this is the case

Where will we end up

Surely many will tell you the graph said that we would be where we are know with eskom

If you followed the trajectory

Imbalanced cells is the same thing

If it drifts enough to be out of balance , if you do nothing you follow the eskom model
 
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leon.davibe said:
You don't have enough data/statistics to say that

Cells drift =fact

If you don't exceed 3.4-3.45v per cell on certain balancers they don't balance and balancing at a lower voltage is problematic for obvious reasons

So if you do 20-80
The shunt will tell you that you are in that range

If one cell drifts apart it can be 10% or even lower

ie that cell gets overworked
And you only noticed that you have lost capacity once you dip below the 60% capacity that you actually use

By that time the cell is toast

Sure if you look at the battery regularly it should show an alarm

On cell low voltage when you get that one or more cells drifted low enough
And can then charge to try and balance the cells if you don't or it's in a position that you cannot see the lights, you will happily abuse cells and be none the wiser
Click to expand...
Just because you have a faulty cell doesn't mean the whole world is like that. Cells are quite happy sitting at 20-80%. Also, a shunt doesn't look at cells. Balancing is only required if you want to achieve absolute capacity out of the battery, either by top balancing (what all bms's do) or bottom balancing, which no one really does.
 
leon.davibe said:
Many like to comment with no real world experience of imbalance in cells

It's too soon to have good data on that so my opinion is just that based on my experience and what i have seen what
Batteries behave like with imbalance

And then use logic to say
If this is the case

Where will we end up

Surely many will tell you the graph said that we would be where we are know with eskom

If you followed the trajectory

Imbalanced cells is the same thing

If it drifts enough to be out of balance , if you do nothing you follow the eskom model
Click to expand...
Again, your real world experience is that you have a faulty cell, **** happens, send it in for warranty and be done with it and stop complaining. Cycling at 20-80 is not going to create a faulty cell period. Actually, nothing you do creates a faulty cell, just **** luck does.
 
wingnut771 said:
Just because you have a faulty cell doesn't mean the whole world is like that. Cells are quite happy sitting at 20-80%. Also, a shunt doesn't look at cells. Balancing is only required if you want to achieve absolute capacity out of the battery, either by top balancing (what all bms's do) or bottom balancing, which no one really does.
Click to expand...
Sorry little bit of bullshit misinformation in there

No you always want your cells balanced mot just for capacity

Since you can still fit into the 20-80 voltage while you have a cell that is below 20% soc

The point of doing 20-80 is to conserve your cycles ,not some of the cells

Based on your response i deduce you have no real world experience on this
 
wingnut771 said:
Again, your real world experience is that you have a faulty cell, **** happens, send it in for warranty and be done with it and stop complaining. Cycling at 20-80 is not going to create a faulty cell period. Actually, nothing you do creates a faulty cell, just **** luck does.
Click to expand...
You can degrade cells faster if you run it lower ie to 100%dod

If you didn't you would not need to do the 20-80 to conserve it you contradict yourself

And naturally you will now work that cell harder all the time if you don't adjust your lifestyle to fit in the new 20-80
 
wingnut771 said:
Again, your real world experience is that you have a faulty cell, **** happens, send it in for warranty and be done with it and stop complaining. Cycling at 20-80 is not going to create a faulty cell period. Actually, nothing you do creates a faulty cell, just **** luck does.
Click to expand...
It's not gonna create a faulty cell

It's gonna create an imbalance in degradation

You series battery is just as powerful as your weakest cell

ie if you have a battery with 15 100ah cells and one 25ah cell

You have a 25ah battery
 
leon.davibe said:
Sorry little bit of bullshit misinformation in there

No you always want your cells balanced mot just for capacity

Since you can still fit into the 20-80 voltage while you have a cell that is below 20% soc

The point of doing 20-80 is to conserve your cycles ,not some of the cells

Based on your response i deduce you have no real world experience on this
Click to expand...
The purpose of 20-80 cycling is that NMC doesn't like to sit at very high or very low voltage, that is it.

I take it you have no real world experience on this either.
 
leon.davibe said:
It's not gonna create a faulty cell

It's gonna create an imbalance in degradation

You series battery is just as powerful as your weakest cell

ie if you have a battery with 15 100ah cells and one 25ah cell

You have a 25ah battery
Click to expand...
No **** sherlock. No balancer in the world will fix that ****.
 
leon.davibe said:
You can degrade cells faster if you run it lower ie to 100%dod

If you didn't you would not need to do the 20-80 to conserve it you contradict yourself

And naturally you will now work that cell harder all the time if you don't adjust your lifestyle to fit in the new 20-80
Click to expand...
Yes, you don't want to got to 0% and then let the voltage sit there, that's not good.
 
If you degrade one cell by 1ah
Due to imbalance

And carry on the trend what happens

ie you think you are at 20% capacity on the pack and you don't know it is actually at 5or3%

It is kinda like if a tree in the forest fall and you are not there to see it fall did it not fall

Sure you can try 20-80 but once every few months do a full charge to see if that is where you are actually at

Just as cells drift shunts can also

So you could happily think you are 20-80

Meanwhile you are 15-75
Or 10-70

Or satisfy the voltage to meet 20% and and have a cell close to empty

I have experienced an imballance before when i just did some stupid ignorant ****

That said battery is full

Load shedding hits 15 min later in the dark, with a bms

Sort out the imbalance pull through 2hrs as if it's nothing

Noe yes i did some realy stupid **** i induced the imbalance

But thought it isn't a problem it has a balancer , it will counter what i am doing

Until you read up and say

Thanks to math there is a snowballs chance in hell that it will sort out the imbalance that i am creating (was a temporary thing until i can get get a dc to dc converter )
 
wingnut771 said:
The purpose of 20-80 cycling is that NMC doesn't like to sit at very high or very low voltage, that is it.

I take it you have no real world experience on this either.
Click to expand...
How many of these are nmc?

A point you like to throw at me when i say they exist in the solar backup market
 
wingnut771 said:
No **** sherlock. No balancer in the world will fix that ****.
Click to expand...
I did not say that is the imbalance showing a point

When it comes to series it is a whole new ball game

And you ALWAYS want your cells balanced in series setups not just when you want the capacity
 
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wingnut771 said:
Pretty much all the portable power stations.
Click to expand...
Which people won't do the 20-80 on , cause the capacity is often so measly you need it fully charge to meet their needs

The point i am making is lifep04 related , oe even if you do the 20-80 on an nmc you would be able to spot an imbalance in the middle of the graph

While with a lifep04 you can have a hefty imbalance , and only pick ip on it if you happen to check the individual cell voltages

When you are right at the bottom almost empty, and right at the top while full charging also not resting as a full cell will come and rest with a voltage difference of less than 0.1v of a cell with 90%soc
 
leon.davibe said:
Which people won't do the 20-80 on , cause the capacity is often so measly you need it fully charge to meet their needs

The point i am making is lifep04 related , oe even if you do the 20-80 on an nmc you would be able to spot an imbalance in the middle of the graph

While with a lifep04 you can have a hefty imbalance , and only pick ip on it if you happen to check the individual cell voltages

When you are right at the bottom almost empty, and right at the top while full charging also not resting as a full cell will come and rest with a voltage difference of less than 0.1v of a cell with 90%soc
Click to expand...
Its like you don't even know what thread your in. o_O
 
leon.davibe said:
Which people won't do the 20-80 on , cause the capacity is often so measly you need it fully charge to meet their needs

The point i am making is lifep04 related , oe even if you do the 20-80 on an nmc you would be able to spot an imbalance in the middle of the graph

While with a lifep04 you can have a hefty imbalance , and only pick ip on it if you happen to check the individual cell voltages

When you are right at the bottom almost empty, and right at the top while full charging also not resting as a full cell will come and rest with a voltage difference of less than 0.1v of a cell with 90%soc
Click to expand...
One of these cells are out of balance which one?

No cheating to go and check old photos
 

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  • IMG_20230223_142633.jpg
    IMG_20230223_142633.jpg
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Anybody that hasn't checked the old photos put in your votes by cell number which one is the one out of balance here i am charging in the middle of the flat portion, and they are in balance
 
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