[EMS Discuss] Getting started at Eugene Maker Space.

Thu Sep 12 13:33:14 PDT 2013

Welcome, Chris!

All batteries are a pain, just some more than others.  Lead-acid is a fine choice if weight isn't an issue.  However,
they can be pretty easily damaged by either over charging or over discharging, so you can't just charge them with your
current wall power supply as is.  (Or you can, sort of.  Adding a regulator would be good.)  Check out Battery
University:  http://batteryuniversity.com/

I have several extra small voltage converters that will turn your battery power into 5V for USB.  You can have one. 
You'll just need the USB ports to plug into and a couple of capacitors.


> Hello Everybody!   I'm Chris Brown.  I just recently got turned onto Eugene
> MakerSpace with a recommendation by one of my friends.  I'm a electronics
> novice, but I haver decided to buy a electronics kit from SparkFun.com.
> Unfortunately, it's on back-order, but hopefully soon, I'll be able to
> purchase the kit and start learning the basics.
> In the meantime, I have a interesting project that I want to start with:
>   I have a portable 12V DC battery-powered speaker system I use all the
> time.  With the volume on pretty low, I can get around 4 hours of listening
> out of it.  I love to take it everywhere and sometimes I would like to play
> it louder and haver it to last longer than it currently has the capability
> to do.
> Therefore, I would like to build a additional battery pack to run it when
> it goes dead, charge it up when not in use, along with putting some 5V USB
> ports on it, so I, or other people can charge their mobile devices, when
> electricity is not available.
> So far my friend has found a couple batteries that might work.  I was told
> not to use Lithium Ion batteries, as they have a history of exploding or
> leaking or not being as stable as Lead-Acid batteries.
> So for we have 2 12V, 5.8Ah Lead-Acid batteries to start with.  We are also
> looking at a power supply that would use the the same 1300mA 12V Universal
> AC Adapter power connector I use to charge my speaker system currently.
> If all goes well, I would like to also use a circuit board and LCD screen
> to display the amount of charge left in the battery, and for it to turn off
> once it's fully charged.  I would like to have it be a 12V AC input, like
> my speaker system, so I can interchangeably charge both at home before I go
> out .
> I don't know much more about it, but here are the specifics on my power
> adapter:
> 1300 mA Universal Adapter
> Input: 100-120VAC 50/60Hz 0.45A max
> Volt DC output: 3,4,5,6,7.5,9,12
> Current: 1300mA
> USB Output: 5VDC/1000mA
> That's all I got for now.  Your advise is appreciated!
> Thanks
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