Wiring 16 cells into 24v battery???

[shaymcquaid]

Hello and thanks for looking.
Will says on his website about 24v 4000watt system:
“This system is a beast! It can handle any solar panel array up to 4000 watts, can handle a large battery bank of 24/12/6 batteries wired to 24 volts, and can power a large 24 volt inverter (inverter size will be limited to battery size in this situation)”

My question is: I plan on buying 16 cells to wire four 12v batteries (4 cells each) and then wire them into a parallel bank of two 24v batteries...

Will says 24/12/6 batteries.
What am I missing?
I don't understand why not 16 cells to equal 24v?‍♂.
Thanks in advance for any input...

-Shay

 

[John Frum]

8x 3.2 volt cells in series is 24 volts nominal.
Parallel 2 of ^ and you still have 24 volts nominal but 2x the watt hours.

 

[FilterGuy]

With 16 LiFePO4 cells, you can get 24 volts a couple ways:


Edit: Updated 2P8S image

 

[shaymcquaid]

Thank you all for your time and knowledge ?

 

[CreativeGuy]

On a related note, I'm wanting to put together an 8 cell 12V battery in a single line like your second diagram. Am I correct in thinking that I would have each two cells in Parallel and the groupings in Series?

 

[LucasH]

With 16 LiFePO4 cells, you can get 24 volts a couple ways:

View attachment 7074
Edit: Updated 2P8S image
View attachment 7076

Could a 16S BMS be applied in either of those configurations?
I'm hoping to build an expandable 24v system. Thought I might start with 8 cells in series, and add another 8 when I need more AmpHrs).
Hello

 

[FilterGuy]

On a related note, I'm wanting to put together an 8 cell 12V battery in a single line like your second diagram. Am I correct in thinking that I would have each two cells in Parallel and the groupings in Series?

Sorry.... I did not see your post till now. Yes. You are correct.

 

[FilterGuy]

Could a 16S BMS be applied in either of those configurations?
I'm hoping to build an expandable 24v system. Thought I might start with 8 cells in series, and add another 8 when I need more AmpHrs).
Hello

For a 24 volt system you need an 8S BMS configuration. For the 8S2P, you must have two seperate BMS configurations.

In your case, you could start with 8S and a BMS. Later on you can add 8 more cells to the system either way. However, if you want to do the 2P8S configuration, you need to make sure the BMS you start with in the original 8S (1P8S) can handle the current of the 2P8S configuration.

 

[Roly]

With 16 LiFePO4 cells, you can get 24 volts a couple ways:

View attachment 7074
Edit: Updated 2P8S image
View attachment 7076

Perfect, just what I was looking for. Thanks

 

[Roly]

For a 24 volt system you need an 8S BMS configuration. For the 8S2P, you must have two seperate BMS configurations.

In your case, you could start with 8S and a BMS. Later on you can add 8 more cells to the system either way. However, if you want to do the 2P8S configuration, you need to make sure the BMS you start with in the original 8S (1P8S) can handle the current of the 2P8S configuration.

With 16 LiFePO4 cells, you can get 24 volts a couple ways:

View attachment 7074
Edit: Updated 2P8S image
View attachment 7076

Perfect, just what I was looking for. Thanks

 

[Factory400]

I have a 16 cell 24v LiFePO4 system that is currently in the 2p8s configuration with a single BMS. It works electrically just fine, but it is too heavy to move and I would like to be able to split it up for other reasons.

I am planning to get 2 BMS's and two independent batteries.

Either config is valid, you just need to think forward about how you will use it. In my case, I wanted to be able to physically move the battery system, periodically charge in two separate locations, have redundancy, etc, etc..... Your needs are most likely different than mine.

 

[Letdasunshine]

Using image 7074 how do I hook up my BMS? I get confused on the second row. Which battery is number 9? Any help will be appreciated!

 

[FilterGuy]

Using image 7074 how do I hook up my BMS? I get confused on the second row. Which battery is number 9? Any help will be appreciated!

This is image 7074


In this layout, you are building two separate batteries. (Each battery has 8 cells). For this setup, two BMSs are needed.

 

[Letdasunshine]

So I can't or shouldn't use one with 16s? I have two 24v banks running parallel.

 

[FilterGuy]

So I can't or shouldn't use one with 16s?

Correct. What BMS do you have?

BTW: you can use a single 8S BMS like this:


However, you need to make sure the BMS will handle the current needed for your loads.

Note:
* Some people do not like this arrangement because the BMS only monitors pairs of cells, not individual cells. I feel that if you start with well-matched cells, this is fine.
* Some people like to build two batteries with two BMSs for redundancy. (If one fails, you still have the other). This is true but 1) Will the single BMS handle the current and 2) having 2 BMSs doubles the chance for a BMS failure.

 

[Letdasunshine]

What is the amp hours your way versus my configuration using two separate 24v banks parralled? Assuming all batteries are 3.2v for 24v battery banks? Thank you for your BMS idea! Not to mention buying 1 BMS v. Two BMS'. Saves a little loot.

 

[time2roll]

So I can't or shouldn't use one with 16s? I have two 24v banks running parallel.

16s is 48 volt battery. If you have a 16s BMS.... some are compatible on a smaller 8s battery with half the sensor wires to be unused. RTFM.

 

[FilterGuy]

What is the amp hours your way versus my configuration using two separate 24v banks paralleled? Assuming all batteries are 3.2v for 24v battery banks? Thank you for your BMS idea! Not to mention buying 1 BMS v. Two BMS'. Saves a little loot.

The amp hours are the same either way.

In both cases, the cells are paralleled. With two batteries, you build the battery and then parallel them. With one battery you parallel the cells (2 cells each group) and then build the battery.

Cell Configurations for 12V 24V and 48V LiFePo4 Batteries

This short deck shows 1P and 2P cell configurations for 12V, 24V & 48V LiFePO4 batteries. To get the deck, click on the orange button at the top of this page. Note: Reviews, Comments and corrections are welcome Document Revision History...

diysolarforum.com

 

[Peckaroo]

This is image 7074
View attachment 81095

In this layout, you are building two separate batteries. (Each battery has 8 cells). For this setup, two BMSs are needed.

What if I use a 16s BMS like this. Would it then manage each cell individually?
I'm planning a build and would rather use only one BMS.

 

[FilterGuy]

What if I use a 16s BMS like this. Would it then manage each cell individually?
I'm planning a build and would rather use only one BMS.

No... the BMS will expect all the cells in series.