Portable Power supply for 2ch amp

brougham99 · 23rd July 2008, 08:07 PM

Hello Everyone,

Just a warning. I am ridiculously new at this, so please don't flame me.

I currently have a small 2 channel Amp that I would like to use portably. (Scythe "KAMA BAY AMP" 2ch Amplifier) . The AC adapter has an output of 12v 3000mA

I also have a couple of Portalac pxl12090 12v 9ah batteries. (but rather only use one at a time)

So my question before blowing everything up, what would be your first steps in making it work. Should I use different batteries? I would like the "stereo" to last for a few hours. Or am I just totally out of wack and do not understand at all, and this can't be done.

B

DigitalJunkie · 26th July 2008, 04:15 AM

Those batteries should work fine.

Assuming no losses,100% battery efficiency,etc... (not real-world!) with 3A of draw,your 9AH batteries would last 3 Hours.

Now,Battery capacity isn't a linear curve...And generally for long-life,you don't want to discharge a lead-acid type battery more than 50% (you can go a bit 'deeper',but 50% is a nice round number)
So,that would drop the usable time to roughly 1.5hours.

That is assuming a *constant* 3A load,which I doubt the amplifier will present,unless you are playing sine waves at full volume. The average draw will likely be much less than 3Amps.

I'd guesstimate that one of your 9AH batteries would run your amp for 3hours,or more before needing to be recharged,depending on volume level,etc.

If that's not long enough,parallel the other battery on there,and double the run-time.

23rd July 2008, 08:07 PM	#1
brougham99 diyAudio Member Join Date: Jul 2008	Portable Power supply for 2ch amp Hello Everyone, Just a warning. I am ridiculously new at this, so please don't flame me. I currently have a small 2 channel Amp that I would like to use portably. (Scythe "KAMA BAY AMP" 2ch Amplifier) . The AC adapter has an output of 12v 3000mA I also have a couple of Portalac pxl12090 12v 9ah batteries. (but rather only use one at a time) So my question before blowing everything up, what would be your first steps in making it work. Should I use different batteries? I would like the "stereo" to last for a few hours. Or am I just totally out of wack and do not understand at all, and this can't be done. B

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26th July 2008, 04:15 AM	#2
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	Those batteries should work fine. Assuming no losses,100% battery efficiency,etc... (not real-world!) with 3A of draw,your 9AH batteries would last 3 Hours. Now,Battery capacity isn't a linear curve...And generally for long-life,you don't want to discharge a lead-acid type battery more than 50% (you can go a bit 'deeper',but 50% is a nice round number) So,that would drop the usable time to roughly 1.5hours. That is assuming a constant 3A load,which I doubt the amplifier will present,unless you are playing sine waves at full volume. The average draw will likely be much less than 3Amps. I'd guesstimate that one of your 9AH batteries would run your amp for 3hours,or more before needing to be recharged,depending on volume level,etc. If that's not long enough,parallel the other battery on there,and double the run-time.

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