Batteries and LED light modules - correctly powering for maximum life


I need to power a LED strip of 3 LED lights with batteries. The LED box says it is a 12VDC light module, and on the back of the box it says the Input Power is 0.0453A. My limited understanding is that I should use a 9V battery plus 2x AA battery (I have limited space - a 8 AA pack wont fit inside my project)...is that correct? I need to know how long these batteries will last - if it is less than 10 hours can you suggest another way of powering it? I'm incredibly lost and very new to understanding all of this! Thanks in advance. 

SonyaS2 (author) 2 years ago

Thank you so much mpilchfamily - I had no idea I shouldn't mix battery types! Thanks!!

Downunder35m - Thanks ever so much for your detailed response - I hadn't thought to use phone battery!

I'm still wiring and testing, and right now I'm my LEDs have been running for 1 week non-stop with the current 12V set-up. (Hooray!)

Sounds good, keep up the work and publish some pics of the finnished project :)

Don't mix battery types. Also a 9V battery isn't worth it. 6 AA will last a lot longer than a single 9V. Your best bet is 8 AA or AAA batteries. If space is really an issue spend the money on some 4.7V lithium batteries.

9 plus 2 times 1.5 somehow equals 12, so for the voltage you should be fine, however mixing batteries like that is not really recommended.

45mA is not very much but there is no way of telling if the batteries will be enough for more than 10 hours of constant use - you would have to try it.

Obviously, the bigger the batteries (in terms of capacity and also size) the longer the LED's will be able to run.

Instead of AA you could use AAA batteries to save some room.

If that is not enough and you want much more than 10 hours of usage time consider flat, recharable batteries for cell phones.

The smaller ones often go for under 10 bucks a piece and a charger for them is in the same price range if you don't care about a china import.

Obviously designing a proper mount with spring contacts would be perfect to avoid soldering every time they need a charge.

Other option for total space saving I could offer are rechargeable batteries for cordless phones, they are small in size and prove 3.7V, sp thre of them will get you close enough to 12V although 4 should not hurt the LED's either.

Some of those phone batteries will definately be able to provide more juice than the little 1.5V packs inside a 9V battery.