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my 9v batter is overheating on the LEDs (This was a DIY project I'm worried I messed up somewhere)? Answered

Hello guys,

I'm pretty new to LED work and this might seem like a really round about process to how I did this but I'm going to explain the whole thing and hopefully find a solution to my problem!

First off I bought these Fairy Lights:  https://www.amazon.com/gp/product/B01MD1RQ6Q/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1

I bought them to put into rave fluffies (that I hope to sell at some point) I've attached photos below of what they look like if people didn't know.
I bought them because of the small battery pack so they could sit nicely along the legs and not bother anyone and, because they're rainbow and do a beautiful blinking pattern. The problem with them is that the battery packs completely sucked. Big time. They would work for about a minute and then start loosing higher voltage colors and then about at the 3 minute mark they would just be totally red. I figured they were crappy batter packs so I decided to mess with it.

Rave Fluffies: http://ep.yimg.com/ay/yhst-11088499841243/striped-fluffies-monster-blue-pink-purple-white-24.jpg

The fairy lights themselves were to short so, I decided to solder to strands together, then I trashed the battery pack that came with them and replaced it with a 9v batter pack adapter. I tested it out on some 9 volt batteries laying around the house and it looked magical. All of the colors stayed much longer and it was beautiful! 

So, today I went out and bought some new batteries they're Energizer Max 9V. I put the fluffies on and put them in and I wanted to test how long they would last. By about 5 minutes I felt a burning against my leg where the battery was. I took the fluffies off fast and discounted the battery. It was extremely hot. Almost to hot to touch and it left two nice low key red burns on my legs.

I don't understand what caused this when the other batteries were fine? I also used a 9V energizer battery before. But, the only difference is I'm not sure how much power was left in it while these were fully powered!

I hoping to find a solution to this and hopefully it's an easy fix!

Bonus points to whoever can send me in the right direction to buy fairy lights like these. Rainbow, blinking, with a small battery pack that doesn't poop out on me fast. I would prefer not to do this much work or something I intend to sell but, if that's what has to happen it's not the end of the world.

Thank you so much!!

Much love,

3 Replies

Jack A Lopez (author)2017-03-10

Have you seen flashingblinkylights.com?


I dunno. It might be the kind of place that sells what you're looking for?

Or worse, it might be a place selling the same thing you want to sell, but at price you can't compete with. That happens sometimes.

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Jack A Lopez (author)2017-03-10

There exist battery holders made to fit 4x AA cells in series, or 4x AAA cells in series, and that will give you approximately the same voltage as 2x CR2032 cells, that is 6 volts.

Another trick might be to try using one of those cheap 5 volt output buck converters.

This gizmo is better known by the name "USB car charger adapter", and at the time of this writing, the local DollarTree(r), if you have one of those in your town, sells these at a price of 1 USD per. Anyway, here is link to what that thing looks like,


I am guessing one of those would work for connecting a 9-volt battery to a low powered load like those fairy lights.

You might have noticed that 9 is not equal to 12, and 6 is not equal to 5, but I still think it would be worth the cost of building one of them, just to see what happens.

A battery holder for 4x AAA cells, might turn out to be the better way to go.

Regarding your question about where to buy flashy trash, like battery powered fairy lights, I guess you've discovered Amazon.com.

I would expect to find similar things at dx.com and banggood.com. These are direct-from-China junkmongers. Although trying it just now, finding something both blinking (or twinkling) AND battery powered is more difficult than finding just solid-on battery powered LED light strings. Actually I only found two,



Of course with a tool like a Google(r) Shopping search, you could search the whole web at once, for "battery twinkle lights"


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steveastrouk (author)2017-03-10

These things are designed to run on 6V (two coin cells) not 9 !

That explains the overheating. 9V batteries will not like that kind of load.

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