I searched online, but the closest to an answer was somebody saying, "Put an Ohmmeter on it." The rest of that thread and other fora were unfortunate devolutions into uselessness and name calling.
With one of my units disconnected from the 120V outlet, I put an meter across the disconnected battery clips, and it was an open circuit. Might there be current, however minuscule, when the clips are attached to the battery? (I've not got an Ammeter.)
Perhaps there's different circuitry in various brands and models that would or wouldn't allow a drain, so here're the two units I have:
(Very basic stuff, and a Porsche Charge-O-Mat I had got flakey a couple years ago.)
Diehard Battery Charger & Maintainer 28.71219
Diehard Battery Charger & Maintainer 71219 (Looks identical to the first. Probably just the packaging's shortened part number.)

but i cant say for sure for that device.

Grant

gee-lenahan-at-gee-mail-dot-com

... but effectively inconsequential. On the order of milliamps per month, etc.

female outlet, rather than using alligator, or clip connectors direct to the battery. Much easier to connect & to disconnect for me & works great. The question I have is, why unplug the battery maintainer except when not in use? I don't see why I would ever unplug the maintainer while it's still connected to the vehicle.

I use Battery Tenders designed for AGM batteries in both vehicles. For the motorcycle, I use Powerlet connectors.



Edited 1 time(s). Last edit at 03/07/2024 05:31PM by John Brown of SE SoDak. (view changes)

I see now, Laz. It would be adding injury to insult if one lost power & the event not only caused the charging to be interrupted, but also drained the battery.

JB/SE SoDak
1997 986 - Wolfi
Yankton, SD

"Wisdom is the most perfect knowledge of the most important truths in the right order of emphasis, accompanied by a total, permanent disposition to live accordingly.

-- Br. Francis Maluf, M.I.C.M.

"(School is to be a factory) in which raw products, children, are to be shaped and formed into finished products . . .(m)anufactured like nails, and the specifications for manufacturing will come from government and industry."

-- Elwood P. Cubberley, Dean of School of Education, Stanford University, 1905

"The creatures that want to live a life of their own, we call wild. If wild, then no matter how harmless, we treat them as outlaws, and those of us who are 'specially well brought up shoot them for fun."

-- Clarence Day, This Simian World

And I have been wondering when I unplug my 2 Battery Tenders from their vehicles, if it hurts leaving them plugged in & their warning lights flashing. Also, is there any or much draw while they're in this state? My instinct tells me I shouldn't leave them that way & usually I don't, but when I do leave them, what's the harm, if any, & what's the cost?

I have a new Fluke 117 multimeter & it's a humdinger. Perhaps I should figure out how to answer my own question regarding draw.



Edited 1 time(s). Last edit at 03/08/2024 05:17PM by John Brown of SE SoDak. (view changes)