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Wire a LiPo into a Field Amp for Music?

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Wire a LiPo into a Field Amp for Music?

Old 04-26-2012, 07:28 AM
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MasterAlex
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Default Wire a LiPo into a Field Amp for Music?

Guys

Somewhat off topic, but I think this is a good place to post. I am putting together a bit of a portable boom box to play while I'm at the field. I have a set of speakers and a portable amplifier that I can use to power the speakers and plug my iPod/Smartphone into for tunes. The Amp is this little guy here. It has a DC power adapter that is a 12V, 2A power supply with the standard power plug as shown here.

My question is this - can I create a wire adapter that allows a 3S LiPo to plug into this little amp? For instance, get some wire and create a dean's end that can connect to the LiPo and the other end to connect to the amp? Thegauge of the wire at the amp end seems really small compared to what we see on ESCs. Anyone done this???

Thoughts?

Thanks!
Old 04-26-2012, 08:03 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

2amps would only need small wires. The amp will only draw what it needs so should be all good. Remember to use a low voltage cut off.
Old 04-26-2012, 08:10 AM
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Default RE: Wire a LiPo into a Field Amp for Music?


ORIGINAL: Goldenduff

2amps would only need small wires. The amp will only draw what it needs so should be all good. Remember to use a low voltage cut off.
Low voltage cut off? What does that mean? Is this something Ineed to add to the adapter? Ithink you're saying not to run the battery to low ... is there something I can add to the adapter that I'll have to make that will do this?
Old 04-27-2012, 05:57 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

A good ESC designed for LiPos will have a cutoff voltage above 3 volts per cell.
This is to protect the battery from damage due to excessive drain.

Good Luck,
KW_Counter
Old 04-27-2012, 06:15 AM
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MasterAlex
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Default RE: Wire a LiPo into a Field Amp for Music?


ORIGINAL: KW_Counter

A good ESC designed for LiPos will have a cutoff voltage above 3 volts per cell.
This is to protect the battery from damage due to excessive drain.

Good Luck,
KW_Counter
Definitely understand. However this setup is to power an Amplifier for a music system at the field. Take a look at the link in my initial note. I want to know if I can wire a 3S LiPo to power the Amplifier and not bring a generator. Goldenduff mentioned LVC and admittedly, I have never seen anything that would accomplish that (other than an ESC). Are you suggesting Ipurchase an ESC? Maybe Iget a 12v field battery and power it that way ...

Thanks.
Old 04-27-2012, 06:48 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

For a couple of bucks you can get a device that plugs in to the balance leads of your lipo. It beeps when voltage is low.

Alternatively if you have a volt meter periodically check the lipo. Time how long you can run the lipo before it reaches say 9.6volts. then on subsequent use you will not have to monitor battery with te voltmeter, just stop when you get to the afore determined time.

Let us know the "run time" when you do it, just curious.

Cheers
Old 04-27-2012, 07:20 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

"Timing the run" doesn't work so well with audio because current draw (and therefore runtime) varies tremendously with type of audio content (lots of bass vs little), overall volume, amount of clipping (distortion). Even though the input of that amp is rated 2A, don't be surprised to see average values around 1A, and peaks over 2A (again depending on content, volume, etc).

Personally that LVA (Low Voltage Alarm) would be the best bet to make sure you don't overdischarge the lipo - you just have to make sure you can hear it over the audio. You could mod the LVA and replace the speaker with a hi-brightness LED/resistor combo so you can see when the LVA activates. This would take a little experimenting.

As to the original question; yes, you can easily make an adapter that goes from Deans to whatever plug the amp uses. Just make sure you have the right polarity at the amp's plug! Incorrect polarity will surely blow the amp. The plug for that specific amp requires the tip to be positive (the "tip" is the inner hole and is +12, the outer sleeve is the ground). Use a voltmeter once you finish the adapter to make sure it's wired right.

Another thing to consider is the lipo voltage. Fresh charge on a 3s pack is 12.6v, and nominal is 11.1v, but some amps shut down below 10-11v.

One more thing; if you use this outside, you may need a bit more power. A house/room has walls to contain/reflect sound so it sounds louder. Outside, the same volume will not sound as loud and you may find yourself turning it up louder to compensate, and if you go too loud, the amp starts to clip which sounds horrible in these "digital" amps.
Old 04-27-2012, 07:35 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

Fair enough but I have a feel for battery use that I augment mentally to account for gliding (0 amps) low speed passes (50amps) and cruising. I cannot see music varying this much given near silence would be 0amps (gliding) and full bass a little over 2amps. 

You could time a base intensive run to be on the safe side.

My LVC things have audio an green/red light and cost about 4 dollars.
Old 04-27-2012, 07:43 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

Thanks Guys!!!! The amp is ordered and I'll post some pics of the setup and let you know how I progress. Apreciate the assistance!
Old 05-01-2012, 07:44 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

Guys

Thanks for the assistance! My amp arrived a couple of days ago and I just got around to wiring a battery adapter so Ican plug in a 3S LiPo. Yes, I will have to monitor the voltage and get some idea of a "safe" amount of time to run this, but Iam very pleased with the outcome. By the way, anyone looking for a mini-amp that packs a wallup, look no further than the guy Ilinked to in my original posting. This little guy ROCKS!

Anyway, here are a few pics of my setup.

Picture1 - My speaker setup - it's tough to see, but the mini-amp is mounted on the back of the speaker cabinet. Very portable and very loud.
Picture2 - Powered up with a trusty Zippy
Picture3 - The adapter I made for this using the barrel adapter linked in my first post and a deans connector - shockingly simple.

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Old 05-01-2012, 07:50 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

Good work, remember if you make a series connector you could increase play times if you have another 3cell

Old 05-01-2012, 07:53 AM
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Default RE: Wire a LiPo into a Field Amp for Music?


ORIGINAL: Goldenduff

Good work, remember if you make a series connector you could increase play times if you have another 3cell

Which Ido!!! Great suggestion!
Old 05-01-2012, 11:06 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

I wouldn't use a SERIES adapter for dual 3s packs (would be 22.2v), but rather a PARALLEL adapter. I bet that's what Goldenduff meant though...
Old 05-01-2012, 11:08 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

No!!!! You do not want to connect another 3S in series. You'll damage the amplifier trying to run it on 6S.
You want a parallel connection to increase capacity and maintain the voltage of a 3S.
I don't know what type of music you will normally play on this system, but if it's heavy metal, then a lead/acid battery would be the best choice It's a joke, just a joke
Pete
Old 05-01-2012, 11:22 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

links/specs to your speakers?
Old 05-01-2012, 11:43 AM
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Default RE: Wire a LiPo into a Field Amp for Music?

Yes my mistake regarding series- sorry!
Old 05-01-2012, 01:00 PM
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Default RE: Wire a LiPo into a Field Amp for Music?

Yeah ... PARALLEL, not SERIES!!! I should have caught that myself. Thanks for the clarity, though ... that's why RCU is so great.
Old 05-01-2012, 01:25 PM
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Default RE: Wire a LiPo into a Field Amp for Music?


ORIGINAL: aerofly0610

links/specs to your speakers?
Igot these from a fellow flyer who wanted to get rid of them ... just gave it to me ... yeah, Iknow - super nice guy. There was no Amp for it, so these were basically taking up space and he needed the room. I was in the right place at the right time. Anyhow, Iknow nothing about the setup (I think he got this in a garage sale) other than it completely ROCKS! Sorry.

I did some poking around and found this ... seems close to what Ihave and definitely priced right.

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