Dc power

Sir Tom of Ato

Member

• Oct 11, 2013

• #1

I was looking to make this amplifier portable https://www.amazon.com/LP-2020A-Lep...F8&qid=1381181611&sr=8-4&keywords=bass+shaker

It has a DC input of 12V 2A, however I know that batteries lose voltage relatively quickly.
My question is, since the amplifier isn't digital, will it still work when a battery has dropped a few volts? Or is there a more advanced way to power it from a battery?

 

M

Mike odom

Active Member

• Oct 11, 2013

• #2

It should still work, but without knowing what the actual amplifier circuit is, it's hard to be certain. We don't know how they bias their interstages.

Even if it does work, as battery voltage goes down, output power will also go down.

 

crutschow

Well-Known Member

Most Helpful Member

• Oct 11, 2013

• #3

That is a switching (digital) amplifier so it should be quite efficient and only use current that is proportional to the output volume. Thus a reasonably sized battery should last awhile if you don't play music at ear splitting levels. Hard to tell though how low a voltage it will operate since that's not stated. But chances are it will operate down to the point where a 12V battery is fairly well discharged (likely as low as you would want to safely discharge a rechargeable battery).

 

audioguru

Well-Known Member

Most Helpful Member

• Oct 11, 2013

• #4

Tripath lied about their digital amplifier ICs then went bankrupt 6 years ago. I think a Chinese company bought the remains of Tripath and made some of the recent ICs.

The Chinese amplifier uses the Tripath TA2020 IC but since the power supply voltage is unknown we do not know its output power.
The TA2020 IC produces 12W or 13W per channel at clipping into 4 ohms or 8W per channel into 8 ohms, when its supply is 13.5V.

A review of the amplifier said it is a pretty good value for its cost of only $21.00. They said it sounds "different" than a high quality linear amplifier.

 

Sir Tom of Ato

Member

• Oct 11, 2013

• #5

Yeah, I am not planning to use this for high quality audio, I just wanted a cheap solution for my project. Would this battery with the charger work with the amplifier? Obviously I would wire it safely.

battery www.amazon.com/Sealed-Lead-Battery-Portable-Finder/dp/B006LO9S3E/ref=sr_1_2?s=sporting-goods&ie=UTF8&qid=1381546195&sr=1-2&keywords=12v+portable+battery

battery charger https://www.amazon.com/Battery-Tend...81547506&sr=8-8&keywords=12v+portable+battery

 

audioguru

Well-Known Member

Most Helpful Member

• Oct 12, 2013

• #6

The amplifier will work for a long time when powered from the huge, heavy and old fashioned lead-acid battery, when the amplifier is playing loudly.
When the amplifier is playing loudly then it might even have enough output voltage swing to drive your LED driver circuit.

The maximum output of the amplifier is a total of 26W into 4 ohms but with music or voice its average total output is about 5W. At an output of 5W its efficiency is 65% so its power draw from the battery averages 5W for sound plus 2.6W for heat for a total power of 7.6W.

At 7.6W the battery current is 7.6W/13.2V= 576mA. The 7Ah battery charge will last 7000mAh/576mA= 12.2 hours.
If you turn down the loudness then a battery charge will last for weeks.

 

Sir Tom of Ato

Member

• Oct 12, 2013

• #7

audioguru said:

The amplifier will work for a long time when powered from the huge, heavy and old fashioned lead-acid battery, when the amplifier is playing loudly.

Click to expand...

I am glad it will work, however you seem to be implying there is a better type of battery that could do this job. Do you have a suggestion?

 

dr pepper

Well-Known Member

Most Helpful Member

• Oct 13, 2013

• #8

I've got some of those tripath amp chips, didnt know they were pants.

 

audioguru

Well-Known Member

Most Helpful Member

• Oct 13, 2013

• #9

Sir Tom of Ato said:

I am glad it will work, however you seem to be implying there is a better type of battery that could do this job. Do you have a suggestion?

Click to expand...

Many years ago I use rechargeable Ni-Cad battery cells for my sound system for the beach. I used C-size for the sub-woofer amp and used AA size for the satellite speakers. Today I would use rechargeable Ni-MH cells or a Li-Po battery (made to power electric RC airplanes).

 

audioguru

Well-Known Member

Most Helpful Member

• Oct 13, 2013

• #10

dr pepper said:

I've got some of those tripath amp chips, didnt know they were pants.

Click to expand...

Today, Texas Instruments make some very good class-D amplifier ICs.

Why do you say that Tripath amp chips are "pants"?

 

Sir Tom of Ato

Member

• Oct 13, 2013

• #11

I have a generic 12v NiMH battery from an RC car that I haven't used in awhile. Assuming it still holds a good charge, any idea if it could power the amp for a decent amount of time?

The battery itself has no power ratings of any kind. The charger outputs "14V DC, 220mA, and 3.08VA" but I don't think that really helps.

 

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audioguru

Well-Known Member

Most Helpful Member

• Oct 13, 2013

• #12

All bets are off when you talk about a no-name-brand "generic" battery.
Name-brand-batteries are stamped with the truthful mAh.

A Ni-MH battery is charged at 1/10th its mAh rating until it is fully charged, then the charger turns off or goes to a low trickle charge. It can be charged at 1/40th its mAh rating continuously.

Charge the battery then use it to power the amplifier and time its playing duration.

 

Sir Tom of Ato

Member

• Oct 13, 2013

• #13

Makes sense, I guess that is the best I can do.

 

Sir Tom of Ato

Member

• Nov 16, 2013

• #14

I figured I should probably just give a quick update: the amplifier ended up not being what I needed for my project, so I don't know whether the battery would have worked or not.