Magnets and batteries

When I’m building a model with working lights, I usually hide the battery in a recess routed out for it in the bottom of the (wooden) base. And then I have to come up with some way to keep it from falling out. In the past, I’ve used screweyes and a bit of wire (disadvantage: has to be retwisted every time I change the battery) or some kind of clever clip bent out of music wire (disadvantage: calls for cleverness) or a little wooden shelf to put it on top of (disadvantage: can fall out).

But last night I had a brainstorm: I glued two flat round supermagnets to the roof of the compartment. The battery has a steel case, so it sticks to the magnets, secure yet easy to remove if I need to. I was pretty proud of that, I can tell you. :slight_smile:

But here’s the question: Is sticking two magnets to the side of the battery going to affect the battery’s function? I don’t know enough about electrochemistry to know whether it’s going to be a problem or not.

no effect on the battery performance is expected.

Have you considered attacking this from the other direction, which is to use different batteries?

It sounds like you’re working with 9 volt batteries. Can the lights be powered with some number of AA or AAA cells, which are normally placed in holders with springs? Or, how about using rechargeable batteries, which you may be able to hide entirely inside the model and communicate to the outside world with a small power socket?

Yes, this.

Thanks, gents. And thanks for the alternative suggestions; I hadn’t thought about permanently installing a rechargeable…

If you go on Amazon you should be able to find a battery holder and create a recess for that. I’d imagine you’d be able to find one for most batteries. Looking quickly, here’s one that holds two double As, there’s also other options for ones that use a cover instead of the plastic wrapping around them. If you have 9v batteries, I’m sure those options are around as well.

Of course, the magnets should be just fine too. If other people handle these models you might want to glue the magnet in just to make sure someone doesn’t throw it out with the battery.

When battery and magnets are placed in contact with each other. The batteries will be discharged because the magnets are electrically conductive.

Only if the magnet is part of a circuit (including the battery), but in this case the magnet is only touching the battery’s outer casing (actually, the label) and is electrically isolated from the battery.

What he’s doing is no different than holding a paper clip to the side of a battery. It’s not going to discharge the battery.

Even the magnet was touching something, it would still have to make contact with both the anode AND cathode (one way or another) before it would be able to run it down.
I have, however, seen that happen with people that toss a battery in their pocket along with a set of keys.