Reply to "Battle Born LFP Battery Capacity Test"

@Gary posted:

We just watched 2 hrs of sat Tv with lights on. 2 cheap group 27 5 yrs old flooded batteries and the control still says 12.6 . In the morning with the furnace set at 58 degrees it will say 12.5 then the sun will be up and in a few hours fully charged. I have to wonder why spend lots of money on lithium when the old technology works so good

@TJeeper posted:

Because lithium batteries are 1/3 the weight, recharge 2-3x faster, last more than 3000 nights off the grid, and will not degrade in life if not fully recharged due to a cloudy short, winter day.  Besides, the inner nerd in me enjoys new technology. 

I camp off the grid 50+ nights a year mostly in AZ in winter.  A set of flooded lead acid batteries lasted less than 3 years.  These days, an equivalent lithium battery is not that much more expensive than flooded lead acid, and will last my lifetime.  YMMV

We're fortunate we have choices. I geek out on stuff too, like Keven. There are several other bullet points to consider in addition to Kevin's when comparing the cost of Li vs FLA chemistries and the camping advantages they offer.

• Adding to his 3000 nights off grid is the advantageous lower cost of Li. Because of their longevity the overall cost is lower than FLA.
  • Drawdown: 50% SOC is recommended with FLA for max life and it seems with 5 yrs on yours, you don't exceed that too often.
    • Li can be fully drawn down (even below 32°) with out effecting the 3000 cycles Kevin notes.
• Winter temperatures effects both battery chemistries when it comes to SOC cycling. FLA's charging rate will slow way down during its absorption stage.  On the other side, Li is limited to recharging above 32°

Just putting the above out there on Jim's @Crewzer's thread. Choices are made based on individual priorities.

Point: I found something similar to Jim's experiment by using inverted DC power to my fridge for the test. My goal wasn't the Pk value but rather to set the accurate zero point to calibrate my battery bank to the 702 Smart BMV. My final voltage was lower, 11.1 as I recall, yielding a total draw down of 368Ah from the rated 340Ah bank. That's about 8% more than the rated 340. The specs on the Dometic 702 in my TT states 2.7A ~AC equating to ~ 25Ah DC before inverter losses.