The BoomCase By Mr. SiMo

Jimmer2000 · 13th August 2011, 04:04 AM

Hi Guys,

So I a trying to build a similar one of these awesome stereos in a suitcase. The problem I cannot figure out is.......What kind of battery is this guy using. He won't tell anyone stating it's " a big secret."

I have a 100 & 140 amp. After the calculations I discovered I need a deep cycle 12v 40Ah batt to last 4-6 hours. Well that battery weighs 30lbs!

I cannot wrap my head around this. IPAD batteries? Help. I got 6 speakers..240 watts with no power. Hmmph.

The BoomCase By Mr. SiMo

Thanks as always.
JC

! · 07:04 PM

You are expecting us to do far too much research, link the specifics of the amp circuit and components itself and mention voltage, current, etc it uses and the space available for a battery pack.

If you want something light weight for transportation reasons go with a class D amp inside to increase efficiency and Li-Ion cell battery pack using something like 18650 cells, but of course they will be a lot more expensive, for ~ 12V 40AH you could put 3 in series for 11.1V nominal and at roughly 2200mAH each, you'd need 18 in parallel so 18 x 3 = 54 cells at about (random guess, I don't know quantity pricing for this amount) $3 each = $162 for the battery pack alone, plus the cost of a special hobby charger and wiring harness to recharge this cell configuration, versus a typical trolling motor (fishing or golf cart type) SLA battery at about $60.

However, I think the project is flawed. If 12V 40Ah lasts (average) 5 hours, that's 12V*40Ah/5h = 96W input, even at half efficiency these suitcase amps can't output 48W RPM without terrible degradation in sound.

So, what I propose is forget about a suitcase as it is not structurally fit for this purpose at all, way too much power and driver resonance for two factors. Build a MDF box with handle on it and put outdoor type carpeting everywhere and metal corners like you see on a portable guitar amp (or just use a guitar amp with a battery pack shoved inside!). Put a class D amp inside. Stick to a more reasonable output power estimate for 5 hours, say 20W RMS...

Suppose 83% efficiency so that's 20/0.83 = 24VA input from 12V battery = 2Ah. Now multiply by 5 hours and you'd need a 12V, 10Ah battery. That would be a MUCH more manageable size and weight for portable use, and for SLA type it costs only $23 or so in the US. Even going with 18650 Li-Ion cells the cost is greatly reduced (though you still need an elaborate hobby charger and harness to recharge that) at 18 cells in 3 series, 5 parallel config = $54 battery pack cost.

Buckapound · 13th August 2011, 08:04 PM

Well, whatever battery he's using, it can't be much, because he's only charging $10 for it. That should tell you there's nothing worth copying there.

From the sound of it, you seem to have an absurdly large amount of power for a small portable device, probably enough to literally shake any suitcase to death. Check out the Boominator thread in the class D forum for an example of a loud, efficient and well engineered boombox. The 12v Tripath and other class D amps are perfect for this kind of application, and I'd be surprised if the suitcase guy was using anything else.

Sealed lead acid batteries work well and are relatively cheap. If you can afford it, lithium iron phosphate cells are state-of-the-art, offering high power for their size and weight (compared to SLA), good sevice life and very quick charging. Lithium ion cells are cheaper but wear out faster, putting out lower voltages as they age. Oh, and check out the YouTube videos of them catching on fire. Hilariously scary!

--Buckapound

! · 13th August 2011, 10:30 PM

^ For $10, it would have to be something like SLA 12V, 3.5 to 4.0 Ah if not less... you can get 12V 7Ah to 8Ah for about $15 on sale, that is the best bang for the buck IMO... it's the size most often used in a typical ~500VA computer UPS.

Jimmer2000 · 14th August 2011, 12:49 AM

So my consult on this project just posed a question. Do these micro amps draw the same amount of power as a car audio amp? Please bare with me...I am pulling my hair out as a newbie...I am sure you get it. Here is what I am considering buying..

4*100W TK2050 TP2050 Tripath D-class Amplifier Board | eBay

This paired with a battery (no idea) running 2 tweets... 2 mids and a 10in sub. Possible?

13th August 2011, 04:04 AM	#1
Jimmer2000 diyAudio Member Join Date: Aug 2011	The BoomCase By Mr. SiMo Hi Guys, So I a trying to build a similar one of these awesome stereos in a suitcase. The problem I cannot figure out is.......What kind of battery is this guy using. He won't tell anyone stating it's " a big secret." I have a 100 & 140 amp. After the calculations I discovered I need a deep cycle 12v 40Ah batt to last 4-6 hours. Well that battery weighs 30lbs! I cannot wrap my head around this. IPAD batteries? Help. I got 6 speakers..240 watts with no power. Hmmph. The BoomCase By Mr. SiMo Thanks as always. JC

13th August 2011, 07:02 PM	#2
! diyAudio Member Join Date: Jun 2005 Location: Midwest	You are expecting us to do far too much research, link the specifics of the amp circuit and components itself and mention voltage, current, etc it uses and the space available for a battery pack. If you want something light weight for transportation reasons go with a class D amp inside to increase efficiency and Li-Ion cell battery pack using something like 18650 cells, but of course they will be a lot more expensive, for ~ 12V 40AH you could put 3 in series for 11.1V nominal and at roughly 2200mAH each, you'd need 18 in parallel so 18 x 3 = 54 cells at about (random guess, I don't know quantity pricing for this amount) $3 each = $162 for the battery pack alone, plus the cost of a special hobby charger and wiring harness to recharge this cell configuration, versus a typical trolling motor (fishing or golf cart type) SLA battery at about $60. However, I think the project is flawed. If 12V 40Ah lasts (average) 5 hours, that's 12V40Ah/5h = 96W input, even at half efficiency these suitcase amps can't output 48W RPM without terrible degradation in sound. So, what I propose is forget about a suitcase as it is not structurally fit for this purpose at all, way too much power and driver resonance for two factors. Build a MDF box with handle on it and put outdoor type carpeting everywhere and metal corners like you see on a portable guitar amp (or just use a guitar amp with a battery pack shoved inside!). Put a class D amp inside. Stick to a more reasonable output power estimate for 5 hours, say 20W RMS... Suppose 83% efficiency so that's 20/0.83 = 24VA input from 12V battery = 2Ah. Now multiply by 5 hours and you'd need a 12V, 10Ah battery. That would be a MUCH more manageable size and weight for portable use, and for SLA type it costs only $23 or so in the US. Even going with 18650 Li-Ion cells the cost is greatly reduced (though you still need an elaborate hobby charger and harness to recharge that) at 18 cells in 3 series, 5 parallel config = $54 battery pack cost. Last edited by !; 13th August 2011 at 07:04 PM.*

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13th August 2011, 08:04 PM	#3
Buckapound diyAudio Member Join Date: Feb 2006 Location: Chicago, IL	Well, whatever battery he's using, it can't be much, because he's only charging $10 for it. That should tell you there's nothing worth copying there. From the sound of it, you seem to have an absurdly large amount of power for a small portable device, probably enough to literally shake any suitcase to death. Check out the Boominator thread in the class D forum for an example of a loud, efficient and well engineered boombox. The 12v Tripath and other class D amps are perfect for this kind of application, and I'd be surprised if the suitcase guy was using anything else. Sealed lead acid batteries work well and are relatively cheap. If you can afford it, lithium iron phosphate cells are state-of-the-art, offering high power for their size and weight (compared to SLA), good sevice life and very quick charging. Lithium ion cells are cheaper but wear out faster, putting out lower voltages as they age. Oh, and check out the YouTube videos of them catching on fire. Hilariously scary! --Buckapound

13th August 2011, 10:30 PM	#4
! diyAudio Member Join Date: Jun 2005 Location: Midwest	^ For $10, it would have to be something like SLA 12V, 3.5 to 4.0 Ah if not less... you can get 12V 7Ah to 8Ah for about $15 on sale, that is the best bang for the buck IMO... it's the size most often used in a typical ~500VA computer UPS.

14th August 2011, 12:49 AM	#5
Jimmer2000 diyAudio Member Join Date: Aug 2011	So my consult on this project just posed a question. Do these micro amps draw the same amount of power as a car audio amp? Please bare with me...I am pulling my hair out as a newbie...I am sure you get it. Here is what I am considering buying.. 4*100W TK2050 TP2050 Tripath D-class Amplifier Board \| eBay This paired with a battery (no idea) running 2 tweets... 2 mids and a 10in sub. Possible?

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