To charge LiFePO4 cells. This charger does not support 3.7V or 4.35V chemistries, which most people will never need anyway. Multi-chemistry support is indeed mostly just for feature fluffing.
As others said, 3.7V limit is also useful for storing li-ion cells in their “relaxed” state. Even this is questionable, however, as they will still self-drain and require routine “halving off”. In actual “storage”, this maintenance seems unlikely to happen.
Adjustable voltage limits are useful, regardless. I’m pretty sure that TK charges her cells to 4.15V to avoid 100% top-off. I would do something similar if I could. Yes, this is unnecessary as our cells are quite durable even when kept at 100%, but some of us are geeks in different ways; I’m an optimizer by nature.
Imagine how annoyed I am that I cannot “fix” my smartphones to keep them from killing their own batteries :smiling_imp: . The desire for longer runtime right now means that they sacrifice long-term battery life. If there was just a setting to reduce the max charge to 96% or so like there is on my laptop…
That Pen L1 is rather interesting. The specs listed are a little weird though - It looks to use a specialty internal USB charged 10900, but the text also says it runs on 10440 and 10400, depending on where you look.
I suspect that they copy and pasted from the C1 information and didn’t proof read very thoroughly. The published output specs are the same for the C1 and L1, and they probably shouldn’t be the same.