Unattended battery charging :)

I have quite a few batteries for all the tools that reside in my shed/garage. From the mower, hedge trimmer, edge cutter, blower to the impact drill, hammer drill, etc. they all have batteries. So I have a shelf where I have all the chargers, but I’d normally have to keep an eye on them and turn the power off when they’re all charged. So I purchased a Smart Outlet and plugged the chargers in it. Then I used CoRE to create this piston:

I waited for all batteries to charge and took note of the 5W the chargers were using up with all batteries charged. Then I still went on and use a number I wanted: 8W. So now, I put the batteries in charge, I push the small round button on the smart outlet to get things started and the outlet will stop on its own when all batteries are done. And then send me a notification too :wink: I am yet to figure out if leaving the battery in the charger with the power off affects the battery in any way, so I’d have to go and remove the batteries when they’re done. But at least they’re not powered on for days - yeah, I’d forget about them :slight_smile:

An easier way to handle your charging needs is through @CSC’s SmartApp here.
Any thoughts?


What amazing app are you using to do this?


SmartThings :slight_smile:


That will never work.

My smart charger app will be out of biz now :grin:


@ady624 is like walmart.

He comes in and puts the little guys out of business.



Oops. Didn’t even look to see if there’s any app out there… idea came to me while I was charging my batteries, implemented the “fix” before they were done :slight_smile:

no worry, I love CoRE :wink:


“Atomically” speaking :wink: , there is always better when there’s more than one way to skin a cat…


Just an fyi, this is hardware based info only.

Inside off each battery charger there is normally some sort of transformer.

Unless there is reverse current prevention technology built into either the charger or the battery (not normally found in things like power tools) leaving a battery plugged into the charger when the charger has no power will cause the battery to discharge via the chargers transformer circuitry.

Just a psa


Good point,now I have to go in my garage and pull the batteries out. BRB…:slight_smile:

Don’t sit them on the concrete floor either… That will not only drain then, but destroy them… Weird…

That is weird. I have a charging station up on a shelf, just like I have for my mobile devices. Was thinking I am being slick turning the power off when fully charged. At least I save power. I noticed that once fully charged, they start sucking on power every 3 minutes.

This is one of the reasons that smart batteries were developed. They shut off the internal charging circuitry.

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Yeah, that’s what I thought but, no. They are smart not to overcharge. But once it goes below 100% they kick the charging again, right? That way if you plug your cell overnight, you have 100% battery in the morning. Talking about vampires

I believe that most devices now will draw power directly from the charger once the battery is fully charged. I think that’s to prevent the dipping of the charge on the battery.

this subject is somewhat “dear to my heart” because batteries can fail in dramatic fashion that burns your house down. A couple of times (I charge mostly LSD NiMH 4-8 pieces per week) in the past 2 years, AA or AAA shorted internally AND the charger did not seem to detect and shutdown as specified, so that battery went to 150F or more. Hot enough to take my fingerprints off - then I implemented an automatic shutdown with RM.

So for “unattended battery charging”, I think independent temperature monitoring and safety shutdown is a good thing. This should be not too hard with RM(may be less reliable) or CORE.


Beet me to iit :slight_smile: Seen that on some, but not sure all do it. I have 4 different brands in the garage.

Hi folks this is a great idea! I had a battery melt while charging not a good thing damn near burned the garage down. I will in deed put this in place!


Read the manual for each charger. Dewalt is typical of a good design:

The charger and battery pack can be left connected with the red light glowing indefinitely. Thecharger will keep the battery pack fresh and fully charged. NOTE: A battery pack will slowly lose its charge when kept out of the charger. If the battery packhas not been kept on maintenance charge, it may need to be recharged before use. A batterypack may also slowly lose its charge if left in a charger that is not plugged into an appropriate AC source.

But it varies. If a charger says to remove batteries immediately after charging then do so, whether it’s powered on or not.

Also, know how to store the batteries whether they are charged or waiting to recycle. More than one verified story of batteries tossed in a plastic bag or a recycling bucket catching fire. They need to be stored where they can’t be shorted. Particularly important if both poles are on the same plane, obviously.

Lithium Li-on batteries have about 12 different things that can go wrong with them. So make sure you know what you’re doing with those.


Personally, I don’t put battery chargers or store batteries in a garage unless it’s temperature controlled as it gets too hot.


Don’t store batteries in the freezer. That’s an urban myth and can damage any kind of battery.


It’s true batteries will last a little longer if stored below 70° and above 40°F, which is why the advice is “store in a cool room” but from a practical point of view they usually do best overall properly stored just in regular living space.


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