I doubt it really matters. I connect in the trunk as I back the car in anyway and that puts the trunk near an outlet. I have a quick disconnect mounted so I do not have to open the "door" in the trim to get to it.

 

WHAT ???

open trunk.

turn little knob on battery door and remove door.

VIOLA ... BATTERY !!!

 

Yes, that does sound simple. Perhaps to remove the battery is a pain in the ass. I thought I recalled removing multiple fasteners and a panel or two. But, is there any difference in the "quality" of re-charging or conditioning when the tender is connected under the hood? There cannot be.

 

I run the pig tail out the battery access panel and close the panel back. It's easier to plug in to the pig tail than to mess with the access door and alligator clips every time. I just pop the trunk, plug up the charger, and close the trunk. Way easier than the hood thing. If it matters you will get a little more from the charger being connected to the battery and not running through the entire car before the current gets to the battery.

 

Better to attach to the battery...maybe. To refine the question: Is charging from the under hood points "good enough"? Seems to work for me.

And now back to important stuff, you know...the "best oil" question!

 

At the end of the day either way works just fine. I attached my quick disconnect harness to the under hood terminals.

Didn't like the idea of either leaving the trunk open or closing the trunk on the harness. With the hood you can at least leave it in the "popped" position.

 

More important question is are you feeding your battery tender "clean power". Would hate to introduce noise in your charging circuit.

Kidding of course, but someone might take it that far.

I tried trunk. It was a pain in the ass and I felt shitty closing the trunk on the cord as it compresses the weatherstrip. Went to the points under the hood, has worked so far and I feel better about it.

 

I connected a pig tail to the underwood location, ran an extension wire through the grill and connect to a charger from there. Works perfectly, no hood or trunk to open ever.

 

Similar, except I just run mine straight down to the ground directly below the underhood connections. Didn't think about going through the grill, but may give that a try. Easier than crawling underneath.

 

I would imagine the circuitry the tenders use to determine when to turn on measure ohms and resistance of the battery to determine it's health. IF they have to go through 12 feet of thick cable that will affect the ohm readings and thus might turn on the charger more of less. Those are so low amp I doubt they could do any damage to the battery from over charging but best to follow what the manufacturer says.

 

... that is why the GR8 has to be used in the "out of car" setting when testing a battery for possible warranty replacement.

 

Also I want to give you maniacs some ideas. Firetrucks and the like use self ejecting plugs to keep them charged up only problem is they look like crap so someone did a drop down plug. Some short vids:

When you start the car a solonoid kicks out the plug.

The company that offers a rull retractable system: