Bigbottlebob

My 09 A8 spends substantial time in the garage during crappy weather months.
(I drive my other cars in those conditions)

Anyway, in reading some threads, the electrical system seems to be sensitive to
chargers, changes, etc.

I have always kept battery tenders on motorcycles, atv's, and other vehicles etc when they will be inactive for a while with great results (as well as fuel stabilizers)

It is a very low amperage "maintainer"
Any thoughts on whether this can cause any issues?

Thanks

Mister Bally

Those work great. No issue with a high quality one that won't catch fire if left in the trunk.

MP4.2+6.0

on dealer showroom floors and trunks, so yes can be fine. Just remember to unplug it when driving off; easier to see it and remember it on the gunwale of my trailered outboard runabout than on my car if I am realistic about chances for an unfortunate mistake.

S8code3

Absolutely! I just watched a guy in a nice BMW drive away with a gas pump and hose still attached to his car.

What are the amp ratings on the chargers you gents are using?

Mister Bally

Most of the maintainers I've seen have 3-5 amp max rating. Remember, we are talking maintenance of batteries, not charging. For charging, I use a 15 amp unit from Sears. Or what's left of Sears.

MP4.2+6.0

The boat maintainer is a low power one from something like West Marine. Comes w/ leads that can be permanently attached at car end and a plug on the lead cable before the charger so that charger box can be removed. Helpful on a boat, bike or whatever to get the charger out of the way. Charger is only the size of several slices of bread. Have used it for years on boat, and on a Vespa when I had it. Never needed on a car, and per my earlier comment it is always easily seen on the boat (gunwale) or scooter (seat) when I use it.

Car charger is the nothing special type from Sears--low and high power charging. Old enough to have a 6/12V switch. Always try to leave a hood open when I charge to remind me (and especially unsuspecting family) from driving off. Was harder when outside with C1, C3 etc. when it was the older back seat VW stuff and similarly w/ D3 trunk.

Bigbottlebob

I will be using a Deltran Battery Tender.
1.25 Amp, and as MP pointed out, leads will be hardwired to the battery terminals (not clip on type) and will have a quick connect/disconnect plug
in the trunk.

mishar

Just spoke with a friend of mine who is electrical engineer and battery specialist. He said that this is not good idea because staying permanently connected it will overcharge battery damaging it. Connecting charger once or twice a month for a couple of hours is way better way to preserve it. Of course that little gauge can be programmed to do something similar.

subit0

So what is the collective group wisdom - leave the trunk open while charging (and try to disconnect the trunk lights) or route the power cable out through a wheel well or opening in the deck lid weatherstripping?

uberwgn

No issues. They want you to connect to the charging points under the hood, not directly at the battery itself.

I've gone thru a couple of Battery Tenders and a couple of the Yuasa equivalents. They seem to range from 1A up to 1.5A in charging mode. The float charge is 10 mA for the Yuasa once the battery is topped off. I don't recall what the rate if for the Deltran unit

Most of these newer cars use an AGM type battery which is quite a bit better in terms of self-discharge compared to a traditional flooded battery. May not be much of a worry at all in terms of letting the car sit.