So, I watched the entire second video. Near the beginning, he does acknowledge that lead acid batteries require careful operation and regular maintenance if one is going to get the maximum rated life from them. Then he also acknowledges that lithium batteries can endure much longer spans without attention if operated within their limits. He must have gotten hammered in the comments.
But then, by the end of the video, he seems to have forgotten all the stuff he said about lead acid when he starts talking about how the BMS in a lithium battery will inevitably fail and kill the battery. Sure, that can and does happen, but I'm not convinced that a BMS failure is more likely than a human failure to properly maintain lead acid.
He makes a decent point about the lack of data on calendar life with LiFePO4. In my comparisons, I've never assumed longer than a 10 year calendar life because I've seen the degradation curve charts he included in his video. Once the claimed cycle life stretched out past 10 years of calendar time, the extra cycles don't matter, so to me it makes no sense spend additional money so that you can baby your LiFePO4 batteries with the hope of getting 5000 cycles instead of 3500.
The other thing that surprised me is that he selected the lead acid battery with the lower life as the better choice (it is cheaper also, though). So I looked up the battery manual for the
NSB100 Blue+ battery. This battery does make some sense for solar in that it is a thin plate battery with relatively low internal resistance and good charge rates. It can produce its rated capacity at a C8 discharge rate. It still suffers from 50% capacity loss at low temperatures and the need to maintain 50% charge at low temperatures to prevent freezing, so 25% usable capacity
He says he is biasing his comparison in favor of lithium by virtue of the operational requirements of his proposed system. However, he makes the same mistakes in this video as he did in the last. He doesn't use the lithium batteries to 90% of discharge, even though that use pattern still allows for a 10 year life span. He also gives the NSB100 Blue+ battery its full life span, which requires temperature controlled operation, and optimal discharge-charge patterns. Below are the relevant quotes from the manual:
For example, if the temperature rises from the
recommended operating temperature of +25°C, to
+45°C, the expected life of the monobloc will decrease
from 10 to 2 years
So both chemistries like to operate at 25°C (77° F). The difference is that the manual says cooling has to be provided for the NSB100 Blue+ if you charge them at high rates. The LiFePO4 batteries generate much less heat during the charge cycle.
Blue+ batteries are designed to be able to operate in
highly cyclic applications as well as PSOC applications.
During optimal PSOC charging regime, NSB Blue+
batteries can be expected to achieve cycle life according
to
the chart below.
This chart to me was the killer, because you have to achieve "Optimal" charge conditions to get the 50% depth of discharge 2000 cycle life he is using in his comparison. If that is the most commonly achieved regimen, why is the other one called "Standard". Standard cuts the cycle life to 1000, which is just under three years. This is probably the life that most people are likely to achieve. Near as I could discern from the manual, Optimal requires specific charge rates depending upon depth of discharge and a 16 hour equalization phase every two weeks. I just don't think that is realistic for most residential solar applications. (I tried looking for the warranty, or the warranty disclaimers because they often spell out the limits of the battery better than the instructions, but I couldn't locate either on the manufacturer website)
Anyway, once again, I'm not saying that no one should use lead acid. What I am saying is that this video doesn't do a good job of representing outcomes under real world conditions. People should pick what works for their budget and system based on data representative of their operating conditions.
Anyway, enough on this from me. Cheers!