Assistance to replace my 12 volt lead acid batteries with 16 lifep04 500ah batteries.

[Fishtank]

Hello, I have purchased 16 lifep04 batteries to replace my lead acid batteries.
I am new to solar systems and want to make sure I am going to do this right. I am off grid and have a magnum inverter and 4 outback charge controlers with a hub. I need to know how to configure the batteries for 12 volts and how can or should I bottom balance or top balance them and which BMS would be the best? I have watched a few videos of Will's but I am not A100% sure how to put it together and set it up safely. Any help is greatly apreciated.
Jody.

 

[jberger]

You need to help us understand how your current system is wired, and what you've purchased to replace it so we can help.
A wiring diagram (it doesn't have to be beautiful), some photos, etc. would help us understand the scope.

 

[John Frum]

Hello, I have purchased 16 lifep04 batteries to replace my lead acid batteries.

batteries or cells?

 

[Steve_S]

16 cells can give you FOUR Battery packs in Simple Series Configuration. DO NOT Parallel cells "unless" they are properly Matched & Batched to have the same IR (Internal Resistance through the working voltage range) - These cost MORE and are not just Voltage & IR matched at static storage voltage which is what 97% of vendors do. Matching & Batching requires 3 passes of charge/discharge with IR measurements at every 50mv point, it is time consuming & costly. There are Matched & Batched cells from factory but again - more $$$.


Please Download THIS RESOURCE it will help you assemble & configure your battery packs.
Luyuan Tech Basic Lifepo4 Guide V1.0A

Hope it helps, Good Luck.

 

[Fishtank]

Thank you guys for the replies, I am grateful for the help. I will take some pics and post them. Steve, I don't understand the diagram you sent, how would I connect them? I will go to the resource you sent, but I realy ned a clear diagram of the four battery packs put together. Thank you again guys. Jody.

 

[Steve_S]

The image shows how you can configure the cells to create a 12V Battery Pack

 

[Fishtank]

Here are a few pics, I don't have the knowledge to give a wiring diagram.
Steve, how would I best connect the two sets of 8 cells together? If I bought a 16 cell bms, would I be able to use it on only 8 cells as well?

 

[Steve_S]

4S BMS is for 12V using 4 cells in Series as shown above.
8S BMS is for 24V using 8 cells in Series. 16S BMS is for 48V using 16 cells in series.

IF you are building 12V then you need a 4S BMS' ! 1 BMS per Battery Pack. So build 4 Packs and install them in Parallel
IF you choose to build a pack with Cells in Parallel as shown above in 2P4S, you still only require a 4S BMS with the sense leads attached to the + side of the cell bus bars.

At this point in time I cannot Recommend a BMS System to use. I would have suggested JKBMS but as of late their hardware has suffered from cost cutting and there are serious quality issues that are a result and also their software side has seriously dropped the ball on many points. A respectable BMS with Active Balancing (Never bother with Passive Balancing if cells are Greater than 50AH Capacity). Generally, 1A Active Balancing per 100AH of Capacity works as a general rule.

Seplos BMS has version interconnectivity & function issues and no Active Balancing
JK have become Hardware & Software problematic due to recent cost cutting measures.
DALY well... there are heaps o issues across the board... just browse the forum.
JBD BMS are OK but only Passive Balancing.
Chargery BMS' are good and use relay's / contactors, their new T Series are more capable but again, only have Passive Balancing and they benefit from having an Active Balancer in line with them, these are not cheap to start with and then you have to add an active balancer for each.

Image below is of a "Component System" with 12V battery packs in Parallel using a Common DC BUS.