My vehicles (240s) sometimes do not get driven for several weeks at a time, and I maintain the batteries by hooking them up to a Battery Tender (drip charge). The Battery tender leads are on each battery post, and have a short lead wire(s) that sticks out an inch or two from the hood, enabling easy hookup to the leads from the plugged-into-the-wall Battery Tender.

If I get an XC90, I'm wondering if a similar hookup will work. Has anyone actually done that? Thanks in advance for any comments.

You could install a covered trailer hook-up connector in the grill of your car and wire it in.

In my XC70 one terminal of the battery is hidden from view - to hook up jumper cables, one uses the positive terminal of the battery and connect the ground cable to an engine mount on top of the engine.

Look in your owner's manual - there probably are locations where you can hook up jumper cables under the hood - your charger could be wired there.

Somewhat far-fetched - See if your cigarette lighter (12v power connection in the console) is live when your car is off. If so, you could also wire this up to trickle charge - if your battery is down to begin with, you could blow a fuse.

When I was at an Interstate battery store, there was a solar charger that connects to the cigarette lighter. I don't know how, or if, it works
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Farewell 'black manta' ('97 850) Hello 'rocket sled' ('06 V70R)

The battery is in the trunk, covered by plastic and a metal cover over that. I do not suspect that the alligator clips will fit under both covers, and allowing the wire leads to be exposed for easy hook up.

Besides, the liftgate has a tight seal and having a wire that is attached to your wall outlet might damage it.

That said, the XC90 has a positive post in the engine bay for easy charger hook up. It is too far in the rear for the short alligator clip wires to stick out of the grill. You need to open the hood.
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Keeping it running is better than buying new