Battery advice for my solar system?

Nah its more of that you will have the limit on what you know about the cells. You only know that they will work with a current of 0.5A. So max current on your packs should be around 0.5A per cells. Im not talking about the time it takes to test them :)
 
Well, even though it takes longer to do the test, it is testing closer to what the cells would actually do in the pack.
 
daromer said:
Nah its more of that you will have the limit on what you know about the cells. You only know that they will work with a current of 0.5A. So max current on your packs should be around 0.5A per cells. Im not talking about the time it takes to test them :)
Click to expand...

Is not enough current for me 0.5A?


I think that if it is applied to every cell in the package up to 0.5A.I'll have to try and see for now.I will write the results from here

Korishan said:
Well, even though it takes longer to do the test, it is testing closer to what the cells would actually do in the pack.
Click to expand...

Actually to test the capacities I want to learn first. At the same time I can see what will happen to the pak. It would be better to experience it.
 
0.5A is generally safer than 1A and will give you more capacity in most cases. If thats your max then its fine :)

I always prefer to test at highest curent. Even though its just a peak thats my goal. If it reflects tad less capacity in total.. That doesnt do anything in long run... if i find out that i have more capacity in end thats just a win-win :)
 
Testing with 1A would of course be better. But is it just right to pay twice as much for it? Do you think the cells tested with 0.5A would be a problem? What's the disadvantage?
 
As i said the difference is that you only know how they perform ar 0.5A. You really dont know if they will survice 1A.

Its 2nd hand cells and we really dont know what kind of abuse they taken before we got em. It might not be any problem running the ones you tested at 1A... But its just that I personally like to know if they can handle it :)
 
OPUS C3100
charge current
200-300-500-700-1000-1500-200
discharge current
200-300-500-700-1000




LiiTOKALA Lii500
charge current

300-500-700-1000
discharge current

250-500
Battery resistance display

available
usb port 1A

available

DAROMER Dedi?im said:
As i said the difference is that you only know how they perform ar 0.5A. You really dont know if they will survice 1A.

Its 2nd hand cells and we really dont know what kind of abuse they taken before we got em. It might not be any problem running the ones you tested at 1A... But its just that I personally like to know if they can handle it :)
Click to expand...

Will I have to retest with at least 1 A current? I have to see what it does at a certain time with another current 1A current. This is going to be better. Thanks for suggesting
 
Ahh yeah it do have 1A.. Bad on me. Go with the ones you going to use :)
 
When testing at .5A, you are seeing what the cell can handle on normal day-to-day usage. Nothing really load intensive. When you test at 1A, you can see what the cell will do closer to a worse case scenario when everything in your house comes online at once kind of thing.
An example would be testing a car engine. Do you test the engine at 2000rpms, to find it's capable HP/Torque, or do you test it at its max rpms to find it's HP/Torque? It's tested at full rpm to get it's full capacity/capability.
That's what we do when we test the cells at 1A. Getting the full capability (or as close to it as possible) of the cells. If you only test at .5A, it may be closer to what you are going to pull normally. But, what if one or more of those cells that tested at .5A were fine, but if they were charged/discharge at 1A, they would start to overheat (example: the red sanyos). This could cause a problem under a heavy load.
"Could" being the operative word.
 
Korishan .5A\ said:
When testing at .5A, you are seeing what the cell can handle on normal day-to-day usage. Nothing really load intensive. When you test at 1A, you can see what the cell will do closer to a worse case scenario when everything in your house comes online at once kind of thing.
An example would be testing a car engine. Do you test the engine at 2000rpms, to find it's capable HP/Torque, or do you test it at its max rpms to find it's HP/Torque? It's tested at full rpm to get it's full capacity/capability.
That's what we do when we test the cells at 1A. Getting the full capability (or as close to it as possible) of the cells. If you only test at .5A, it may be closer to what you are going to pull normally. But, what if one or more of those cells that tested at .5A were fine, but if they were charged/discharge at 1A, they would start to overheat (example: the red sanyos). This could cause a problem under a heavy load.
"Could" being the operative word.
Click to expand...

Do you reduce the risk of raising the number of cells in the package? Example: average cell capacity 2000Mah 14x80x2x3.7 = 8.288 Wh
Inverter maximum value 3000W
Maximum current value for each cell = 0.723938Mah

If this calculation is true, my cells will give an average current of 0.723938 mA at full capacity.


14x100s Maximum current value for each cell = 0.579151Mah

Is it correct?
 
Your inverted rated at 3000W is it's max "output", not input; though, the two are tied together. You need to check your inverters max Amp Draw under full load (this also includes surge draw as well).

So, your inverter is rated at 48V input. To supply 3000W it would need at least 62.5A draw. The inverter is not 100% conversion, so there are losses. We'll say 70A draw to be safe

2000 mAh @ 3.7 = 7.4 Wh, or 7.4 Watts. To get 3000W, you would need 406 cells @ 2000 mAh. 70A / 406 cells = .17 A per cell.


I'm not sure, but I think I'm way off on the above :s The numbers don't seem right. (guess we'll both learn something here )

This is the part I'm still learning on :p I'm not fully sure of the math required for conversions.


Side Note: milli-amphour is mAh, not Mah. The Amp is always capitalized, not the m. Just a lil nit picky in that area as some of the others are here as well ;)
 
I think you have mixed your stuff together a bit :) (Though correct correct calculation)
First of all milli = m. M = Mega :)

If your inverter is max 3000W you will have a current of:
14*3,7V = 51,8V nominal
3000W/51,8V = 58A
58A/80cells = 0,72A => 720mA

And yes the more cells the less stress on the cells. Less current and smaller cycles also results in more cycles but at same time less Wh used per cycle. So its a delicate mix.

Edit: Korishan was faster but had some erros in his calculation?

Note that i did NOT include losses in above calculation. So add as korishan said from the 58A another 10-15% atleast!

Edit2: Perhaps not errors but he calcualted based on 3kWh... Perhaps not what was wanted unless you also want to be able to run the system under certain time. Though you missed that you need to do it on total ie if you go 3kWh of storage and get 400 cells thats 400/14 = 28 cells. And then its 70/28 = 2.5A per cell ;)
 
Hahah, thanks daromer!!! :) funny how we both posted at the same time. Probably took you a lot shorter time to post it than did me, tho :p
 
:)
I updated my post. Hope it makes sense. A little mix in your calculations. In mine to hehe
 
Calculation right out of losses. Packing with 100 cells is no problem.

When cells use 65A current power
14x100s Maximum current value for each cell = 0.656371mah

This value is very close to the Liitokala Lii500 test value. It's not a problem, right?
 
mA not mAh ;)

I will most likely work.
 
mA is capacity (size of your petrol tank)
mAh is how long will the capacity last (kilometer/liter)

Cells are measured (normally) in mA. But this number can be directly related to mAh. If a cell has a capacity of 2000mA, then drawing 1A(1000mA) of current, the cell should last 2 hours. 1A * 2hrs = 2Ahs (1000mA * 2hrs = 2000mAhs)

Teacher Kori :p
 
Nah cells are meassured in Ah or mAh... But then they also have indication of the max current and all that. And thats in A.
A cell cannot have a capacity of 2000mA ;) its mAh Korishan. I have never seen capacity being meassured in A on a cell.. Unless its china crap
 
LOL Yep, you're right. I got that backwards. My brain was working in reverse for some odd reason.

Soo, under correction:
Cells are measured (normally) in mAh. But this number can be directly related to mA. If a cell has a capacity of 2000mAh, then drawing 1A(1000mA) of current, the cell should last 2 hours. 1A * 2hrs = 2Ahs (1000mA * 2hrs = 2000mAhs)

Ok, did I get it right that time? :p
 
Yeah kind of :) capacity is just A*h :) Eya lets not spam his thread.
 
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