Originally Posted by SomeCarGuy
When they get really low the charger doesn’t sense them. Have to hook at regular battery up to it so it will take charge. As long as they aren’t way low they take charge.

Concur with this. ^^^
I have a 6 yr old RedTop in my Cuda (seldom driven). It used to run down from sitting and had trouble getting it to take a charge. I keep a Schumacher tender on it now (for several years) and it keeps it topped off. No issues.