Hydrometer on the replacement battery?

[lambition]

I just changed battery on solara and got curious about something.

Are there any replacement battery with built in hydrometer?
Most batteries that are installed in the manufactures has built in hydrometer on the battery, but I don't see hydrometer on any batteries that you can buy from part shops.
Why is that?

Hydrometer did not help me in anyway in the past, so I don't really care. Charge state can be found with multimeter and water level can be found just by popping the cap.
Still I'm curious why they don't have one installed.


Are Kirkland batteries really as good as other brands? I see pretty good reviews about them, and it is the cheapest battery I found. So, I just got Kirkland.
It was only $59.99 with 640 CCA and 800 CA, while other brands run around $80 to 90.

Solara came with 24F battery, but Costco don't have 24F and recommends 35 instead. It is a bit smaller battery, yet it had higher CCA compared to stock battery. Stock battery was only 600 CCA, so it's an upgrade