[izquierdaste]

Hey guys,

I was thinking of trying to use a battery for a couple of 12v dacs and tranportable amplifiers that I own. I found the following battery on ebay. I know that I an sla would have the most capacity, but I don't really want to keep an sla in my apartment for a number of reasons (especially because I think my girlfriend would finally draw the line if I brought one home).

Anyways, I found this lithium 12v, 1800mah battery on ebay. It seems like it might be what I am looking for so I was wondering if anyone has tried one of these out. Also, I was wondering the capacity of the batteries that come with high-end dacs as a reference point. Here is a link to the battery I was looking at:

http://cgi.ebay.com/12V-1800mAh-Lith...QQcmdZViewItem

I have no affiliation with the seller and I would assume they are overstating the capacity a bit.

 

[cotdt]

i would also add some capacitors to go along with the batteries for better sound quality.

 

[izquierdaste]

I am just getting my feet wet with mods. Are you saying that, in general, it is better to add capacitance to the power supply input of the dac?

 

[kramer5150]

Quote:

Originally Posted by izquierdaste /img/forum/go_quote.gif I am just getting my feet wet with mods. Are you saying that, in general, it is better to add capacitance to the power supply input of the dac?

Batteries need capacitance/storage for instantaneous current reserves on-demand. My understanding is that batteries are "sluggish" when it comes to delivering current for transients, while a capacitor can completely discharge in milliseconds. Hence the need for capacitance.

Most DIY amp designs however are designed with power supply caps integral to the power section of the circuit. Assuming you pick the right cap for your amp, that should suffice.

I was just looking at that battery last night. 12V 1.8 amps is PRETTY beefy, so I'm guessing its larger and heavier than it looks in the pics. Unless of course it is severely over-rated.

 

[izquierdaste]

Quote:

Originally Posted by kramer5150 /img/forum/go_quote.gif I was just looking at that battery last night. 12V 1.8 amps is PRETTY beefy, so I'm guessing its larger and heavier than it looks in the pics. Unless of course it is severely over-rated.

Thanks for the info. I asked the manufacturer about the maximum current draw for the battery, so I'll let you know if I hear back.

It doesn't look very big next to the ac adapter, which is only rated at 200mA. My guess is that it is over-rated. If you buy Chinese digital camera batteries, they are always rated higher than OEM. However, they last about the same amount of time in practice. I would hope that it would be at least 1200 mah, which I think would be fine for my desktop use, especially since I have the ac backup.

 

[Herandu]

If you are going to use it with your TC-7510 it should do the job, but the TCC/MKII version has smaller power caps than the MKIII. Factor is 12:1. That means 220uF in the TCC/MKII and 4700uF in the MKIII. Best uprate the power cap in your DAC if you are going to use a battery. I run both my MKII and MKIII off a car battery at times, which is actually tucked away in a converted Jack Daniels wooden crate. So it looks nice kind of, and no questions asked what I have in the box

.

 

[izquierdaste]

Quote:

Originally Posted by Herandu /img/forum/go_quote.gif If you are going to use it with your TC-7510 it should do the job, but the TCC/MKII version has smaller power caps than the MKIII. Factor is 12:1. That means 220uF in the TCC/MKII and 4700uF in the MKIII. Best uprate the power cap in your DAC if you are going to use a battery. I run both my MKII and MKIII off a car battery at times, which is actually tucked away in a converted Jack Daniels wooden crate. So it looks nice kind of, and no questions asked what I have in the box .

I have a panasonic fc on the way to swap out. I also havesome elna caps and opa2107 and lm4562 to try as opamps. Hopefully, it will make a difference. Might wait on the battery since the market fall was a bit of a downer.

 

[Herandu]

Quote:

Originally Posted by izquierdaste /img/forum/go_quote.gif I have a panasonic fc on the way to swap out. I also havesome elna caps and opa2107 and lm4562 to try as opamps. Hopefully, it will make a difference. Might wait on the battery since the market fall was a bit of a downer.

The Panasonic caps are going to make a big difference. OPAMP is a bit more tricky to fit. I have tapped into the PCB at the DAC output and made up a new circuit with vero board. It has different caps and IC sockets. On one unit I have an adapter PCB like the one in the link I showed you.
I am going to make this as a proper PCB and perhaps put it up as a mod idea. Excuse me whilst I don't show images of my tampered unit. It's a secret

.

 

[regal]

Quote:

Originally Posted by kramer5150 /img/forum/go_quote.gif Batteries need capacitance/storage for instantaneous current reserves on-demand. My understanding is that batteries are "sluggish" when it comes to delivering current for transients, while a capacitor can completely discharge in milliseconds. Hence the need for capacitance. .

You're thinking of old style batteries. These new Lithium Ions have a low output impedance, I doubt the need for new capacitors. I would place the battery as close to the DAC as you can.