Battery configuration to increase V & AH

[Absentrush]

Hi guys, please help or assist.
I have 8 x 3.2v LiFePO4 200ah cells. I want to configure them to output 24v with 400 or 800ah. How do I bus bar them correctly? All the diagrams I have seen in Google images and here do not SEEM to cover this configuration, unless my eyeglasses need upgrading? Your input with a quick diagram would be marvelous. Thanks in advance helpers

 

[daviddakers]

So 4 x 3.2 would be 12v... 12v + 12v in series would be 24v.... but still at 200ah... Or 12v + 12v in parallel would be 400ah but still 12v... Can't do any better without more cells.

 

[Absentrush]

Hmmm, I guess that's why I can't find what I'm looking for. Thanks very much for your swift reply. I really need another 4 or 8 cells to make the battery bank more exciting, is that correct?

 

[daviddakers]

8 to make 12v 800ah or 24v 400ah.

 

[Q-Dog]

8 X 3.2, 200ah cells in series is 24 volts at 200ah. If you want 400ah you need to double that. So it would take 16 200ah cells, or 8 400ah cells to get to 400ah at 24 volts.

 

[daviddakers]

Hmmm, I guess that's why I can't find what I'm looking for. Thanks very much for your swift reply. I really need another 4 or 8 cells to make the battery bank more exciting, is that correct?

4 could make 12v 600ah... you could get 24v 300ah with 12 cells... but you would need to reconfig.

 

[Forbisher]

Hi guys, please help or assist.
I have 8 x 3.2v LiFePO4 200ah cells. I want to configure them to output 24v with 400 or 800ah. How do I bus bar them correctly? All the diagrams I have seen in Google images and here do not SEEM to cover this configuration, unless my eyeglasses need upgrading? Your input with a quick diagram would be marvelous. Thanks in advance helpers

8 x 3.2V 200Ah in Series is 25.6V at 200Ah
For 24V 400Ah you will need another 8 200Ah cells.

 

[Absentrush]

Great help. I'm off to the battery store today. My smart inverter is 24v so I have to configure my system with that in mind. Much appreciated ;-)

 

[Forbisher]

Great help. I'm off to the bettery store today.

Don't Bet it all on red.
What Store are you buying 3.2V 200Ah cells from and how much?

 

[Absentrush]

Don't Bet it all on red.
What Store are you buying 3.2V 200Ah cells from and how much?

I bought these 8 cells 6 months ago now and they have been sitting without charge all that time waiting for my electrician to finally install them today. They lost 0.06 volts over that time from receiving them and are all on the exact same charge I'm therefore going back to Sunrays solutions local to me, to get 8 more of the same. They cost approx £470 or $666

 

[Steve_S]

Have a LOOK at this Document about assembling & Configuring your LFP Cells.

Luyuan Tech Basic Lifepo4 Guide

This document was posted to the forum by Amy from Shenzhen Luyuan and written by Steve S. It was meant to be posted as a resource. Below is her description of the resource: Dear all friends in the forum, This file in the attachment was...

diysolarforum.com

24V System requires 8 Cells to make a Straight Series Pack.
Cells can be put in Parallel within a Pack to double the Amp Hours.
-> This IS NOT SUGGESTED with Unmatched & Unbinned cells. They WILL deviate a lot between each other.
--- Cells that are Paralleled, appear as One Cell to the BMS System, therefore it cannot manage each individual cell. Matched & Batched cells are used in Parallel (think EV's etc) which are matching for Internal Resistance & Impedance throughout their entire operating range, so they all function identically. Matched & Batched cells typically cost 20-50% than Bulk Commodity Cells used for ESS System. See the Link to the Article in my Signature, as well.

Setting Battey Packs in Parallel IE 2x24V/200AH will still provide you 400AH but will also be more Fault Tolerant as well it will share the Charge/Discharge loads on the system and if one shuts down for any reason the other keeps running.

Each Pack will require an 8S BMS (MAX 200A Discharge & 100A Charge capable), one Fuse (not greater than 200A).
Each Pack should be wired to a Common DC Bus using (=)(-) Busbars rated for 300A.
Each pack to BusBar and Busbar to Inverter should use the Same Gauge Cabling. !! Oversizing Batt Wires is a Good Idea as 1) you can future proof a bit but also 2) to reduce resistance and voltage drop. Besides Copper is frightfully expensive, so you only want to buy it once.

Myself, I run 24V with 1190AH of LFP & 856AH of Heavy Lead. All my Battery Wires are 4/0 gauge (120 mm2) from Batt terminals through to Inverter/Charger. They still warm up when taking more than 100A charge but nothing serious. I started my Solar Build based on a 2000W Inverter and used 2/0 Gauge wires but when I upgraded to 4000W I also had to update the wiring to 4/0 and OUCH that stung a bit.

Hope it helps, Good Luck and peruse the links in my Signature.

 

[Forbisher]

I bought these 8 cells 6 months ago now and they have been sitting without charge all that time waiting for my electrician to finally install them today. They lost 0.06 volts over that time from receiving them and are all on the exact same charge I'm therefore going back to Sunrays solutions local to me, to get 8 more of the same. They cost approx £470 or $666

What BMS are you using?
Or are you using a BMS?

 

[Absentrush]

What BMS are you using?
Or are you using a BMS?

8s 100amp

 

[GSXR1000]

I bought these 8 cells 6 months ago now and they have been sitting without charge all that time waiting for my electrician to finally install them today. They lost 0.06 volts over that time from receiving them and are all on the exact same charge I'm therefore going back to Sunrays solutions local to me, to get 8 more of the same. They cost approx £470 or $666

how do you know they are at the same charge? you can have same voltage and totally different charge...
I suggest top balance

 

[Absentrush]

Yes, I get that thanks My smart charger is telling me that my batteries combined are at 26.3 volts currently but my SOC is less than 50%. I am a little confused as to a couple of other settings on my charger/inverter...I have been instructed to set my bulk charge at 29.2v & my float charge the same. Is that normal? I thought one had to be slightly lower than the other? I have a DALY BMS coming in the post in the next couple of days...will that rectify all instead of using the user defined settings in my charger to top balance my 8 cells? I am not using the system at present, just setting it up, so any help will go a long way for a quick learner ;-) These are my batteries for your perusal.

 

[NPhil]

Hi guys, please help or assist.
I have 8 x 3.2v LiFePO4 200ah cells. I want to configure them to output 24v with 400 or 800ah. How do I bus bar them correctly? All the diagrams I have seen in Google images and here do not SEEM to cover this configuration, unless my eyeglasses need upgrading? Your input with a quick diagram would be marvelous. Thanks in advance helpers

It's not in the diagrams because the bus bars which connect to 8 more 200AH cells in an alternate universe (for 400AH at 24V) or 24 more (for 800AH at 24V) are top secret.

 

[Absentrush]

It's not in the diagrams because the bus bars which connect to 8 more 200AH cells in an alternate universe (for 400AH at 24V) or 24 more (for 800AH at 24V) are top secret.

If you make your own bus bars from flattened copper pipe, nothing is beyond doable ;-)

 

[GSXR1000]

Yes, I get that thanks My smart charger is telling me that my batteries combined are at 26.3 volts currently but my SOC is less than 50%. I am a little confused as to a couple of other settings on my charger/inverter...I have been instructed to set my bulk charge at 29.2v & my float charge the same. Is that normal? I thought one had to be slightly lower than the other? I have a DALY BMS coming in the post in the next couple of days...will that rectify all instead of using the user defined settings in my charger to top balance my 8 cells? I am not using the system at present, just setting it up, so any help will go a long way for a quick learner ;-) These are my batteries for your perusal.

BMS will not to balance your battery's...
also your BMS should not stop the charging of your batteries...
I charge mine to 90% so 13.8v (27.6v for you) float at 13.73 (27.46]
for 100% and faster charging then I would say 28.8v and 27.5 for float

 

[Absentrush]

BMS will not to balance your battery's...
also your BMS should not stop the charging of your batteries...
I charge mine to 90% so 13.8v (27.6v for you) float at 13.73 (27.46]
for 100% and faster charging then I would say 28.8v and 27.5 for float

Those last settings you have given are nigh on the same as the defaults so I'm guessing that's where I should be? My battery manufacturer recommended I float at 29.2v or 3.65v per cell so I'm a tad confused...maybe they want me to charge to 100% max constantly, but I've read a lot of stuff and am happy to run up to 90% to keep the batteries and system healthy. Thanks for your input. It's much appreciated ;-)

 

[NPhil]

If you make your own bus bars from flattened copper pipe, nothing is beyond doable ;-)

My recommendation is to keep them round, so you can make them spin. That way, you don't wind up with an annoyed general ordering you to "make it spin."