Blackmagic cinema camera battery

My camera came with a Sony NP 570 clone which looks identical to a Kastar spare that I bought. Several years ago I bought a couple for something else and today they are nearly worthless, despite not using them but charging them occasionally.

Are there any brands that last longer than others? What brand comes with the camera, mine was unbranded. I read that it's best to store these L type batteries at about ½ of a full charge if you are not using them.

Can anyone add to this info?

It's true that storing L-type batteries at around 50% charge can help extend their lifespan. In terms of reliable brands, Sony's original batteries tend to last longer, but brands like Watson and Wasabi are also known for good performance.