LifePo4 Voltage at .5C - .6C Discharge

FWC wrote:

otrfun wrote:
Any idea what the under-load voltage during this flat period would be?

I would hope LifePo4's could easily maintain at least 12.0v while under .5C - .6C discharge down to 20% SOC.

I hear lots of discussion about LifePo4 high charge rates at a given charge voltage, but very little discussion about discharge voltage while under heavy load. Got to have both to make the battery productive.

To answer this question - yes they should be able to maintain 12V under a < 1C load down ~10% SOC. Here is a typical discharge curve (multiply by 4 for a 12V battery):

Our two Costco GC2's are rated at approx. 200+ ah. However, I'd guess-estimate only about 30-35% (60-70ah) of that is accessible with a 125a load (true since new). The *battery* voltage drop while under this much load is just too high. Our inverter goes into low-voltage shutdown around 10.9v. FWIW, we only have a .15v - .20v voltage drop at 125a (battery terminal to inverter terminal).

It would appear to be a very different story with the LifePo4's. For folks like us, who need access to 125a on a regular basis, we should be able to easily access 160ah (or 80% of the rated 200ah) of two paralleled 100 ah LifePo4 batteries while easily maintaining at least 12.0v while under a 125a load. If the graph that you posted is to be believed, it would seem two 100ah LifePo4's (i.e., Battleborn or Lifeblue) offer a huge performance advantage over our two GC2's.