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battery advice for a Lepai powered boombox?

post #1 of 8
Thread Starter 

My girl friend has a spare Lepai LP-2020A+ and she decided she wants to make a boom box out of that and a suit case.  We have everything but the power source figured out.  what size battery would be needed for at least 4 preferably 6 hours of music, not full volume but loud enough to be able to enjoy at a lake or camping or something. Also is there a compact AC to DC charger that could be squeezed into the case with an appropriate sized battery?  

 

This is what I'm imagining but i don't really know much about big portable and rechargeable batteries ->  http://www.amazon.com/Spypoint-12-Volt-Rechargeable-Battery-Charger/dp/B002NYN7EM/ref=sr_1_1?ie=UTF8&qid=1395801067&sr=8-1&keywords=Spypoint+12-Volt

 

 

for those curious:

speaker wise we are going to use  ->  http://www.sonicelectronix.com/item_61010_Rockford-Fosgate-PRIME-R165-S.html  <- and I'm going to build a MDF speaker box in the suit case. I put a pair of those in a friends jeep and they have held up great to the weather so i imagine they will do fine for a cheap little boom box.  also i will put a build thread together once it is finished :)

post #2 of 8

I'd go with 10 AA NiMh cells:- http://www.amazon.com/AmazonBasics-NiMH-Precharged-Rechargeable-Batteries/dp/B007B9NV8Q/ref=sr_1_1?ie=UTF8&qid=1395864675&sr=8-1&keywords=aa+rechargeable+batteries

 

...in a pack like this:- http://www.ebay.com/itm/Battery-case-box-holder-for-x-10AA-size-cells-15V-0522-/281107208346?pt=LH_DefaultDomain_2&hash=item41734b989a

 

...it says 15V, but that's for alkaline cells.

 

You can arrange to charge these from a wall-wart, or simply use a standard-type charger. Try a fully-charged pack of 10 cells, see how long it takes to run down. If you don't get the duration, you can have a second set of batteries to swap in, or 2 packs of 16 will give you 3*10-packs, with 2 spare. You will need to exercise some discipline, don't mix charged and uncharged cells, it's better to assemble them into packs that are left intact more-or-less for the life of the cells.

 

You could use a lead-acid type battery, preferably a gel-type leisure battery, but AA MiMh's and their chargers are a regular consumer items, and are probably preferable in a low-maintenance, no-frills system. You probably have many other gadgets that can use these cells.

 

I prefer these Pioneer speakers:- http://www.sonicelectronix.com/item_39878_Pioneer-TS-G1644R.html, cheaper, but with 91dB vs. 89 for the Rockford Fosgates, will get you a bit more volume, or a bit longer play time.

 

w

post #3 of 8

Quite a coincidence, I've just accumulated nearly all the parts for a DIY powered speaker box of my own.   Wakibaki's recommendation is good, safe and quite complete (as usual from him - nice:)  Here's a more advanced/potentially less safe route I've chosen to pursue.  Only those knowledgeable & comfortable in Li-ion use should even consider this risk/reward balance, I'm in no way recommending it.

 

Lithium-Ion cells have a much higher energy density (power/weight advantage) but have much higher safety risk if the implementation is not proper.  This includes using top-shelf, reliable components like genuine Panasonic cells & robust/tested charge/discharge circuitry.   I've a non-commercial history w/Li-ions dating back to my son's R/C car days & invested many hours researching & testing/confirming my use of them.  There are plenty of dramatic youtube videos of forced Li-ion explosions to enjoy that could influence those not comfortable/sure of what they are doing.  That said everyone likely has several Li-ion-powered devices around, my approach is quite similar to that used in 18650-based laptop batteries.

 

Building this thing because could not find something sufficiently like it commercially & due to DIY impulses:)  Want a compact, portable, lightweight, rechargeable "boombox" - possibly w/Bluetooth receiver down the road.  As it's more for patio, garage, driveway use, etc stereo imaging is not important so I'm choosing a stereo single speaker (using MCM 50-14020).  Will use new genuine Panasonic 18650 cells in an metal box sub-enclosure along with robust fleabay "Protection Board for 3 Packs 12.6V Li-ion Lithium 18650 Battery charger 4A" board including thermistor.  Box will be 1 cu ft or so & may try porting.  Plan to get going on it in a month or 2. 

 

Didn't plan to post about it here as its not headphone related but since this thread was around....   

post #4 of 8
Thread Starter 

thanks for the replies, i kept looking stuff up ad i ended up using a 12v 12Ahr lawnmower battery, its wired to a male plug for the amp and a female plug that is on the outside of the case for recharging.  I have used it for about 4-5 hours with ought a recharge of any kind and its still going stong.  im going to make another one that is all around nicer and ill see if i can remember to make a how to thread for it.

 

thanks again, Kane

post #5 of 8

Best advise by far is just buy a pre built (insert anything) because by the time you are done buying batteries, charger, amp and speakers the BOM plus time spent will be staggering.

post #6 of 8
Quote:
Originally Posted by bootdsc View Post

Best advise by far is just buy a pre built (insert anything) because by the time you are done buying batteries, charger, amp and speakers the BOM plus time spent will be staggering.
You know what sub forum this is right? And the same could be said of most hobbies. Sense of accomplishment / workmanship is not quite the same sitting on the couch and pressing BUY button for ready-made gear.
post #7 of 8
Quote:
Originally Posted by cfcubed View Post


You know what sub forum this is right? And the same could be said of most hobbies. Sense of accomplishment / workmanship is not quite the same sitting on the couch and pressing BUY button for ready-made gear.

I know all about, My home made portable speaker is sitting at my feat atm and it was a pain to build, cost more then ready made portable and well the looks leave much to be desired.

 

Now that spypoint battery and charger will work fine, 12v is okay but as the battery drains the voltage drops and the amp will start to distort so a 14v-16v pack would be better. 7AH will last a long time at low volume, I use the same size but different brand. You can add a self powered bluetooth adapter, any cheap one from amazon will do. I went down this road last year and wish i hadn't bothered, its not just the cost of materials but the value of your time you need to consider.

post #8 of 8
Thank you for elaborating, helps support your advice:). Nice to hear the details / experience you've had with the build.
Sometimes the thing you build doesn't turn out as nice or practical as the image you had of it. Hoping that doesn't happen for my build:)
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