[kaptain]

Very interesting and shows that BB has developed a superior BMS than other brands.

This is an interesting point, but I'd like to see some facts to validate this.
I tried Google to find out what makes BBB's BMS unique and how it's different from others, whether its BMS has a built-in balance function, or uses distributed function, etc. In the end, I really haven't really found any specifics to validate that argument- its BMS being different or 'superior'.

However, I do see BBB has a 10-year warranty, while most others vary from 5 years to 11 years.
My understanding is that most, if not all LiFePO4 types of batteries have a built-in BMS, its basic functions include protecting each individual cell from over/under voltage, over/under temperature, short circuits, and high currents.

On its website does say the serial connection is limited to up to 4. And unlimited in parallel.

   

And I see someone posted some good questions on BBs website in March 2022, and that question didn't receive an answer.


   

btw, I found some coupons, if someone decided to buy BB batteries and looking for a discount.

   

And a couple of articles to share on serial and parallel connections, I believe Dakota Lithium is the one that offers 11 years warranty.

1) How to wire in parallel or in series.

2) Explaining the limits of LiFePO4 batteries in parallel.

[SouthernDevGirl]

The DIY solar link on the first page is filled with bad information.  To anyone stumbling on this link, please don't read that post.

The link in @"kaptain"'s post just above (Explaining the limits of LifePO4 batteries in parallel) is written by someone with a true technical understanding of the reasoning; that is a very good article.

Regarding the original poster's question...

• The common BattleBorn 1.2kWh battery is going to run about 82% DoD to maximize your cycle-count.
  
• To get 1000 cycles out of a 3.06kWh Lifeline 8D battery, you can't exceed 50% DoD.
  

In short, a BattleBorn 100Ah / 1200kWh battery yields about 984 Wh.  The Lifeline 8D yields about 1,530 Wh if you choose to avoid discharging more than 50%; however, many people will not realize when the 50% threshold is crossed and for this reason, it's conceivable that someone may get 2+ kWh from a Lifeline 8D when not discharging at too high of rate.

To put that in practical terms, you would require about 1.5 to 2x BattleBorn 1.2kWh batteries for every Lifeline 8D that you replace, if your concern is kWh / longevity of power output.

Obviously these change based on speed of discharge (although in the BattleBorn instance it won't change much due to a 30p cell design, providing high-output without substantial loss in performance) and temperature.

Keep in mind, the benefit to Lithium chemistry (whether Lithium Iron Phosphate or conventional Lithium-Ion) is the exceptionally high cycle-count/lifetime and very high-consistency voltage over the discharge curve.  The BattleBorn will last you many thousands of cycles based on the setup of the BMS (to answer an earlier post, it's a decent BMS; however, nothing better than what you'd use if you were going DIY) and the 30p4s x 26650 cells used.

Battleborn, using LifePO4 intrinsically has more cycles to start with; once you cap the voltage rate with the BMS and if you manually limit the cutoff to about 12.9v (that will be about 12.8 at the battery, with the shunt reading 12.9, after resistance) that battery has the potential to outlast the coach at a 80%+ DoD.

Ergo - many benefits, including reduced weight, reduced self-drain, more consistent power, MUCH longer lifetime -- however, when compared to the 8D Lifelines at 50% DoD, you are not going to get more Amp Hours.

Speaking of BattleBorns specifically, they run a 26650 cell (120 per 1.2kWh battery, aha 100ah); if you total the actual watt-hours, you get (3.2v nominal * 3400mah * 120 cells = 1305.6Wh).  What that means, in essence, is that BB is underrating their batteries which is exceptionally uncommon.  It also means they are likely limiting the SoC to about 95% or similar, which means they're already extending the batterie's lifetime without you having to reduce the max charge voltage.

In short -- the answer to the original poster's second question about the actual charging curve -- you would be best setting the low cutoff to 12.9v (which is essentially 12.8, giving you an 83% DoD and greatly extending the life).  The high-side of the charge appears to be managed by BB's integrated BMS and it appears it's keeping the cells slightly below their max voltage, which essentially means that you're already getting a great SoC-versus-lifetime-longevity ratio.

I hope that makes sense.  If not, please let me know and I'll be happy to elaborate.