Dac + car battery?
Jul 16, 2008 at 6:31 PM Post #2 of 13

StanleyB1

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I can't comment on the DAC you mentioned since I have never tried one of them. What I can tell you is that you can use a 12V car battery with a DAC if the DAC has a 12Volts input and has voltage regulators inside it. The car battery voltage will be higher at full charge, and drop as the charge runs out. This will affect the supply line of the DAC, so that supply line needs to be a regulated one if you don't want a drop in performance. From experience I can also mention that you'll know when the battery needs recharging: the TOSLINK input starts to play up.
 
Sep 22, 2008 at 11:15 PM Post #4 of 13

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I'd like to bring this up, again because last time I remember seeing a post about using a car battery with audio equipment, it was suggested that the use of something like a trickle-switch needed to be used; not because the voltage variation, but because the initial current spike is so gigantic compared to the little stuff people power their cMoy's off of that it would destroy your electronics or at least blow the fuses every time.

I was considering buying an Optima battery (so I don't have to worry about gasses or leaking) to power project amplifiers and the like, but I don't want to blow my stuff up. What do I need to have between a 12V Optima (over 1000 CCA) and my project amps?
 
Sep 23, 2008 at 8:29 AM Post #7 of 13

krmathis

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I don't see why it wont work.
There are battery powered DAC's out there (I have the RWA Isabellina), which performs really well off-grid.
 
Sep 23, 2008 at 8:43 AM Post #8 of 13

PhaedrusX

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i can't speak for the Apogee Mini-Dac, but the 12V Optima 34 Red Top battery has been recommended as a good match for audio purposes.
 
Sep 23, 2008 at 9:32 AM Post #9 of 13

leveller1642

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Quote:

Originally Posted by PhaedrusX /img/forum/go_quote.gif
i can't speak for the Apogee Mini-Dac, but the 12V Optima 34 Red Top battery has been recommended as a good match for audio purposes.


A car battery is probably not the best choice for this purpose. A quick google told me that this battery is a starting battery. It has thin plates designed to deliver maximum current for a very short period. A deep discharge will kill a car battery.

You really need a deep cycle battery. It has thicker plates and is designed for a much deeper discharge. They are measured in Amp Hours where car starting batteries are rated by their cold cranking amps capacity. You have the choice of either an gel type or an absorbed glass mat (AGM) if you don't want to use a wet cell.The AGM has the advantage of accepting higher charge rates (15 volts) like a wet cell, where the gel is limited to a charge rate of 14.2 volts and needs a non standard charger.

My own power is clean as I have solar charged batteries converted to mains power by a high quality sine wave inverter.
 
Sep 23, 2008 at 10:30 AM Post #11 of 13

leveller1642

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Quote:

Originally Posted by xenithon /img/forum/go_quote.gif
I used a 5A 12V SLA (sealed lead acid) battery when I had the Apogee Mini-DAC. Worked live a charm and was indeed superior to the wall-wart supply.


SLA's are a gel battery. I should have checked the Mini's power consumption earlier. It only draws 5 watts according to apogee. The car sized battery is definitely overkill.

Current X voltage = watts.

So on 12 volts the mini draws .416 amps. Do the maths and decide what size battery you need for the amount of time you need to run it, remembering that a full discharge will dramatically decrease the life of the battery. I'd plan on only going to 50% discharge as a compromise. Ideally around 80% discharge would ensure the maximum number of charge/discharge cycles from the battery. Going on that, xenithon's 5 a/h SLA would be good for about 6 hours.
 
Sep 23, 2008 at 1:06 PM Post #12 of 13

PhaedrusX

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Quote:

Originally Posted by leveller1642 /img/forum/go_quote.gif
A car battery is probably not the best choice for this purpose. A quick google told me that this battery is a starting battery. It has thin plates designed to deliver maximum current for a very short period. A deep discharge will kill a car battery.

You really need a deep cycle battery. It has thicker plates and is designed for a much deeper discharge. They are measured in Amp Hours where car starting batteries are rated by their cold cranking amps capacity. You have the choice of either an gel type or an absorbed glass mat (AGM) if you don't want to use a wet cell.The AGM has the advantage of accepting higher charge rates (15 volts) like a wet cell, where the gel is limited to a charge rate of 14.2 volts and needs a non standard charger....



hmm...at least one designer of BYOB (Bring Your Own Battery) designs, Charles Altmann, recommends the Red Top for his Attraction DAC. this, despite the existence of the Yellow Top, also by Optima, which is a deep cycle battery.

if this high burst of current exists, as you say, it doesn't have a detrimental effect on the Altmann Dac.

i use a Monica DAC, and have seen these powered by Red Tops as well without issues. i'm considering going off the grid too, so am curious if this really is or isn't a cause for concern.
 
Sep 23, 2008 at 6:16 PM Post #13 of 13

leveller1642

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The Altman DAC apparently draws only .2 of a amp. I cannot understand why around 20 kg of discharge sensitive battery would be recommended.

That is a question i'd be asking Mr Altmann before accepting this advice.

EDIT- Sorry, but he does not actually recommend the red top.

The Altmann BYOB amplifier

Quote:

The next time your car battery needs to be replaced, don't throw away your only source of clean power. If it can't turn your car's starter motor anymore, it is still perfect to be used with the BYOB amp.

I personally use a 10 years old Optima Red Top starter battery, which is a non-spillable high-quality high-performance battery. With one charge I can enjoy extensive listening for 2..4 weeks.

For charging, I use a standard battery charger. Most of you already have a car battery charger. If not, it's not expensive and a good thing to have... Good chargers are available from Einhell.


 

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