Possible very flexible, accurate, and less expensive lithium system

[GeorgeRad]

No, that is not how it is used. We are doing what is referred to commonly as "midrange charging", which is just what it sounds like it is. The low end SOC is 35% and when we get that low in use, we charge to 80% SOC and stop charging. We cycle only between 35 and 80% in use and when stored.

There are quite a lot of claims that midrange use is much easier on lithium batteries and preserves capacity longer. But, now there is getting to be a bunch of information coming out that says that aging is more of an issue for lithium than many of the things that are said to be best for long life. One of the sources I saw said that lithium life (down to 80% total capacity test) is roughly 7-9 years unless they are abused. I think that means you should get around 9 years if you take good care of them and 7 with moderate care. For most of us they will age out long before we hit the cycle life of them, but in applications that may charge like 3-5 times a day then preserving life carefully to last longer might make a time difference also.

That is about the same as well managed good AGMs, my lasted 11 years, so lithium advantages are smaller sizes and lower weight.

 

[booster]

That is about the same as well managed good AGMs, my lasted 11 years, so lithium advantages are smaller sizes and lower weight.

Yep, I have also mentioned that several times myself, but heavy users would probably get more cycles within those same years. If you got 2000 instead of 1000 cycle equivalents (for lack of a better term, actually total amp hours in and out time divided by usable capacity). You would need to charge capacity 250 times a year for 8 years.

Size and weight are advantages but lower internal resistance so they can run large draws at lower SOC is another. The biggest, IMO, is that you can do the mid range charging because it shortens the charge cycle by hours and is actual good for the lithiums while it is bad for the AGMs.

All of this goes to show why some of us were so skeptical of the original claims of 10K= cycle life at 100% discharge etc that the sellers pushed early on to justify the pricing back then.

 

[dicktill]

<snip> The biggest, IMO, is that you can do the mid range charging because it shortens the charge cycle by hours and is actual good for the lithiums while it is bad for the AGMs.

<snip>

Why is that?

 

[booster]

Why is that?

AGMs need to get to 100% full regularly to maintain capacity and not get the very common "walk down" of capacity that comes with not getting full often enough. It is kind of link they get a "memory" in terms of other stuff and, I think do to sulfation build up that once it gets old won't convert when the battery is attempted to charge further. Many/most chargers and systems don't charge long enough in absorption to get totally full which can take 3-4 hours to go from 85% to full and total times approaching 10 hours for a full charge from 20% SOC. That is why many of us liked our solar as it is perfect for the lower amp tapering charge at the end of a charge cycle and doesn't require driving or shore power to do. Our 440ah bank of Lifeline AGMs needed to get all the way down to 2 amps charging at absorption voltage to be full per the Lifeline spec of .5%C amps.