This is one very good reason that the world gives me a headache.
Physics is physics. The chemical process by which car batteries work generates hydrogen as a byproduct. And it also causes the electrolyte to evaporate
Granted, newer batteries use materials which reduce these actions, but to not eliminate it. So how the frak can they possibly claim "maintainence free" status?
Like is said. The world gives me a headache.
Also, I don't know if it's just Panasonic, but rather Toyota's choice in OEM battery suppliers overall.
My 2000 Tacoma had her original battery in her in late 2008 when she met the crusher, and I never even had cause to think about it. Never even 1 time slow cranking, etc. And we do get winter here. I don't know what brand it was, however.