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# hooking up a 9-volt battery to a lazer pointer Answered

have you ever had a lazer pointer that was really fun, but then ran out of batteries? those little replacement batteries are hard to find. while I was supprised there weren't any instructables on this, I'll be posting one soon. I know how to use a 9-volt battery to power the lazer pointer again. this fuel cell is easy to find, and easy to work with. comments? are you interested?

## Discussions

It turns out that 9V batteries aren't actually all that efficient, in turns of energy storage. See the discussion on the MintyBoost instructable:

9V battery: 9V x 500mAh = 4.5Wh power
AA battery: 1.5V x 3000mAh = 4.5Wh power!

Since it sounds like you need 4.5V, you could put 3 AA batteries in series - you'll get exactly the right voltage, and they'll last at least 3 times longer than the 9V battery!

ya the most you can run one of those el cheapo 1\$ lasers would be maybe MAYBE 5 volts. 9 volts it wouldn't last 10 seconds trust me i deal with lasers ALOT when im not in school and you have to get the voltages perfect. now if you could find a 4.5 volt battery or just use 3 AAA's with an AMPERAGE of like.. 125 amps, then you would be cooking. Ha, it's a pun.

I need this Instructable so I can convince my parents to buy me a lazer pointer. lol

take apart the 9 volt battery and there are smaller batteries in it, hopefully the round kind, especially if you have a pen laser that actually takes That Size (AAAA) of battery! Test the polarity because some of the AAAA's in 9 volts actually have the bump on the wrong end. Some 9volts have weird flat cells in them.

Well wouldn't it depend on how much voltage the laser can handle?

actually. my awesome "invention" broke. either it shorted out, or it had something to do with my dad running it over with his car a few times. lol

9 volts is too much voltage to run a cheapy laser pointer on, at most 4.5 volts will be all you need and is very bright.

Sure, let us see it. That's why we are here waiting for each new Instructable.

Well, most new instructables.