Peukerts Law and evaluating true SoC

[VanHausen]

Well your conclusions are wrong based on junk science. One fact you missed is heat losses from resistance has absolutely nothing to do with Peukert Law or Amp Hours. You are making it up.

Care to explain the "correct" science then? Anyone can just call something 'junk' and walk away.

I'm certainly willing to accept it has nothing to do with Peukerts law. In fact, if you read the post fully, or look back at my earlier statements, you would have seen that the case I made from the beginning is that capacity reduction modeled by Peukerts Law is indeed not due to resistive heating.

The fact remains all my testing seems to show I can remove roughly the same amount of work from the batteries with a high discharge, followed by a low one, as I can with a single continuous low discharge. If I have missed some aspect of the theory here, I'd love to learn it.

And - can you please do so without indulging your usual tendency to belittle and insult those you are talking to?

[Mike90250]

These results were likely from pretty fresh batteries. Older batteries with a 100 cycles or so, are not likely to fare as well recovering.
What happens internally in the battery, is fresh electrolyte can't circulate fast enough to supply the reaction needed. After it sits a bit,you get some redistribution. But it is pretty interesting how close the #'s are to the spec.

[VanHausen]

These results were likely from pretty fresh batteries. Older batteries with a 100 cycles or so, are not likely to fare as well recovering.
What happens internally in the battery, is fresh electrolyte can't circulate fast enough to supply the reaction needed. After it sits a bit,you get some redistribution. But it is pretty interesting how close the #'s are to the spec.

The sacrificial Vision battery was 1 year old, spent its life on float as a standby UPS. We were surprised by the performance too - we will likely install them in future projects.

The fullrivers I'm using were also 2nd hand when I got them, and I'd say are about 5-6 years old at this point. Theyre showing some signs of slight capacity reduction but still sit well within the parameters Fullriver specify. They've had very judicious and regular charge/overcharging - the Trimetric/SC2030 has proven its worth . Nonetheless the trend seems the same - take out a nominal % of C20 capacity at 20a, or at 100a, and after 24hrs rest, the OCV is basically the same. We've observed this on multiple in-use systems now. It does seem to echo what the documentation from Bogart Engineering says...I'm hoping to meet with a local EE Prof who specializes in battery research next week and have a chat with her about it.

I'm familiar with the concept of localized electrolyte depletion and agree that would make sense to explain the voltage sag, and reduced effective capacity at high amps. It would also explain the voltage recovery we observed after giving the battery a good rest after heavy loads.

I still think the base level sanity check is the most convince one here. The cumulative energy difference between the stated capacity of the battery at say C2 vs C20, is whopping. If that energy was truly removed from the battery, as in spent, it would have to manifest in some way, namely heat. That's a LOT of heat...so where's it going, if we;re not noticing it as boiling batteries and glowing wire?

Only sensible theory I can come up with it that it's not really gone. The fact that we can discharge a battery to nominally 100% DoD, then rest it, and continue getting work out of it at a lower discharge rate, supports this theory.