I picked up a battery tender that I spotted at Costco because I've heard they significantly extend gel battery life. But is that only for cars in storage or can cars/batteries in everyday use also benefit? (would one then have to connect every night?)

finally, do we just use the jumper-cable posts located under the hood to connect the battery tender or does the connection have to be to the actual battery squirreled away in the trunk?
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TIA.

 

I saw them there too last week, but already have one.
The tender is meant to be used if you go on vacation for a few weeks or need to store the car for longer. It is not for vehicles driven every day or a few times a week. It is not needed in that situation as normal driving maintains the battery. Mine is the original at 63,000 miles.
It can be connected to the convenience jumper cable posts under the hood.
I use it sometimes but only on my RX as it is driven less than the HS or if going on vacation.