Battery and inverter setup for busking.

[ninerfan]

I'm looking at putting together a small PA to go out and busk with. I will need to have a singer, 2 guitars and bass in the PA. Not so loud we get shut down, just loud enough to keep up with a cajon. So I'm thinking about getting a 12v RV deep cycle battery from Costco and an inverter from amazon like this one: https://www.amazon.com/BESTEK-1000W...1538510074&sr=1-25&keywords=inverters+12+volt or this one: https://www.amazon.com/Ampeak-2000W...&pf_rd_p=bde7b808-4983-454b-9a71-59c1fc01c0c2.
I have a Carvin xp1000l which is 400w RMS per side or I could get a Carvin xp800l which is 250w RMS per side. I will be running them into 2 Carvin 12" monitors.
My question is, "will this work"? If so, how long will the battery last? Any help would be greatly appreciated!

 

[Matthijs]

It will work. Done something very similar a few times. With a 100kwh battery I could do a few hours without any problems, even with a mid size guitar tube amp connected.

 

[Jazz Ad]

This kind of conversion is very inefficient. You'd have it better on all accounts buying a real portable PA.
Something like a SubZero P12 will work just fine.

 

[Wasnex]

Here's a recent thread you might find interesting and informative.
PA system for busking

Here are some fairly high quality power packs I researched after participating in the thread...the two 400 series have pure sine wave output, but not cheap.
Goal Zero - Discover Products - Portable Power Stations/Goal Zero

 

[ninerfan]

Here's a recent thread you might find interesting and informative.
PA system for busking

Here are some fairly high quality power packs I researched after participating in the thread...the two 400 series have pure sine wave output, but not cheap.
Goal Zero - Discover Products - Portable Power Stations/Goal Zero

I appreciate the help. Would a battery and an inverter last longer than a power pack like the goalzero or one of these?
https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias=aps&field-keywords=ac+power+pack

 

[ninerfan]

I'm trying to see if I can make it work with what I've got. I have a 5th wheel and can pull the battery to use. I have the carvin PA and speakers/monitors. I can run it in stereo so each guitar can be panned to separate them. Bass and Vox down the middle. Some built in effects for the vox as well. If I can go that route I only need to buy the inverter for $100 or so.

 

[ninerfan]

I could get a lower wattage PA (the Carvin 800l), but would have to push it harder to get the same volume.

 

[ninerfan]

I could use both of the batteries from my trailer as well...

 

[Jazz Ad]

All your inverter solutions are more expensive than a standalone battery powered PA.

 

[Wasnex]

I appreciate the help. Would a battery and an inverter last longer than a power pack like the goalzero or one of these?
https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias=aps&field-keywords=ac+power+pack

By last longer, do you mean reliability or provide power longer.

In regards to reliability. I believe the Goal Zero batteries are replaceable, and the unit is high quality but I don't have any idea how long the product would last or how repairable it is. The Goal Zero has controls that limit how far it will discharge the battery to prevent damage to your equipment and the battery. If you buy an inverter you probably should look for a similar feature and also evaluate the quality if it's output. Some units produce a pretty high quality modified sine output, but some produce a really dirty output that may not work well with audio or digital circuits.

As far as providing power longer...that depends upon how big of a battery you get and how efficient the inverter is versus how big of a Goal Zero you get. The Goal Zero products are just sophisticated batteries and inverters in a slick package. They provide pretty decent tech specs so you can compare. You can find tech specs for the Goal Zero Yeti 400 and Yeti 400 Lithium Here:
Invalid Link Removed
Yeti 400 Lithium Portable Power Station / Solar Generator | Goal Zero

Note the continuous and surge current and power these two devices can put out ranges from (2.5-2.6A) 300W to 600W.

Here's a page that estimates how long the various Goal Zero power stations can supply power for various electronic devices.
Goal Zero - Discover Products - Portable Power Stations/Goal Zero

 

[ninerfan]

All your inverter solutions are more expensive than a standalone battery powered PA.

I could go with a $100 inverter and have a stereo 400W per side PA (not that i would crank it out). It seems all of the standalone PAs are 100W or less and the nicer ones are >$500

 

[JKos]

I could get a lower wattage PA (the Carvin 800l), but would have to push it harder to get the same volume.

It's not about the rated output of the amp, it is about the efficiency of the amp. A 2000 W amp that is 85% efficient is better then a 100 W amp that is 70%.

For your given application, you won't be pushing anything close the power levels you mention. Not even close.

- John

 

[ninerfan]

It's not about the rated output of the amp, it is about the efficiency of the amp. A 2000 W amp that is 85% efficient is better then a 100 W amp that is 70%.

For your given application, you won't be pushing anything close the power levels you mention. Not even close.

- John

I think I understand. I believe my Carvin PA to be pretty efficient. It has 2 class D amplifiers. I really do appreciate everyone's input, it's a tough thing for me to wrap my brain around. I like the thought of using my PA because we can plop down the 2 monitors behind or on either side of us, plug in the bass, guitars and mic and go. I get that there are other, better solutions (that cost more $), but am trying to figure out if my setup would work and for how long (10 min, 1 hr, 6 hrs?).
1 or 2 deep cycle RV batteries (already have)
inverter 1,000W? (need to buy)
Carvin PA 400W class D amp X2 (already have)
Carvin 12" monitors (already have)
I have a Harbor Freight cart I could have it all set up on. Take the monitors off the cart, plug them in. Plug in Guitars (DI), bass (DI), and mic and go. (Cajon for drums)

 

[Robb Fesig]

So I'm going to make some assumptions here, hopefully to get you a decent ball park time (warning: I may be way off and I take no responsibility for this not working out this way (If it's better than my estimate and you want to give me the credit, feel free)).

To start, 2 Carvin amps that output 400 watts of audio at 90% efficiency would draw 440 watts at 120 volts.
So that makes 880 watts being drawn at peak by the PA.

880 watts at 120 volts = 7.3 amps of current draw

For the sake of putting some numbers on paper, let's say your DC to AC invertor is 90% efficient as well. That would mean to output 880 watts, it would draw 968 watts.

968 watts at 120 volts = 8.06 amps of current draw

So, let's say your looking at 968 watts for peak output. The inverter has to pull the power out of the battery, and it can only do so at 12 volts. To get 968 watts out of a 12 volt source, it will have to pull 80.6 amps.
So, at max power, a deep cycle marine battery (or a bunch of them) with a Ah rating of 744 could run the PA at max output for three hours.

You won't be running the PA at max output constantly because music doesn't work that way. You could probably get away with saying 240 watts constant output, which would make your battery required drop to 184.6 Ah (or 1 4D Deep Cycle Marine Battery)

Hopefully this helps and isn't too far off reality. You should try it

 

[ninerfan]

So I'm going to make some assumptions here, hopefully to get you a decent ball park time (warning: I may be way off and I take no responsibility for this not working out this way (If it's better than my estimate and you want to give me the credit, feel free)).

To start, 2 Carvin amps that output 400 watts of audio at 90% efficiency would draw 440 watts at 120 volts.
So that makes 880 watts being drawn at peak by the PA.

880 watts at 120 volts = 7.3 amps of current draw

For the sake of putting some numbers on paper, let's say your DC to AC invertor is 90% efficient as well. That would mean to output 880 watts, it would draw 968 watts.

968 watts at 120 volts = 8.06 amps of current draw

So, let's say your looking at 968 watts for peak output. The inverter has to pull the power out of the battery, and it can only do so at 12 volts. To get 968 watts out of a 12 volt source, it will have to pull 80.6 amps.
So, at max power, a deep cycle marine battery (or a bunch of them) with a Ah rating of 744 could run the PA at max output for three hours.

You won't be running the PA at max output constantly because music doesn't work that way. You could probably get away with saying 240 watts constant output, which would make your battery required drop to 184.6 Ah (or 1 4D Deep Cycle Marine Battery)

Hopefully this helps and isn't too far off reality. You should try it

Thank you! That's really what I've been looking for!

Would I be better off going with a lower wattage PA which I would have to push harder or keeping what I got and not running it as hard?

How big of an inverter should I be looking for?

 

[Robb Fesig]

Thank you! That's really what I've been looking for!

Would I be better off going with a lower wattage PA which I would have to push harder or keeping what I got and not running it as hard?

How big of an inverter should I be looking for?

I'd go 1000w inverter. Buy it on Amazon or somewhere that you can return it if you can't get the results you want.

As far as which PA to go with, I'd go with speakers that have the highest sensitivity, and amps that have the highest efficiency. An amp won't draw more power that it needs, so the rated output wattage is irrelevant. A 400 watt max output amp running at 200 watts will draw 220 watts , and a 800 watt max output amp running at 200 watts will draw 220 watts, provided they are both 90% efficient (and the efficiency is constant across their power output). So it's more about efficiency than output power. The best way to determine what you should do is just try it.

Also, I would put a high-pass filter on at least the bass guitar, but ideally on everything if you can. Reproducing low frequencies requires the most power. Even if the speakers cannot actually turn the output into sound, the amplifier will still try to amplify it and still consume the power.

Good luck! And be sure to report back what you find. On paper this works, but real life isn't paper

 

[CallMeAl]

I did this, but only for a bass amp, so not quite the power draw youre talking about. I ran it for a 1 hour set, 2-3 × a month. Battery lasted about a year.

Isnt there a way to check the battery to see how much juice it has? Then you could monitor to see how much you are using. Or take a back up battery, but theyre heavy as hell!

Short answer is yes it works. Just a matter of matching the right inverter to your pa.

 

[Deltatim]

There are meters thal can be run on the battery that tell you battery voltage, current draw, charge current, amp hours used, etc. Usually find them on solar power systems.

 

[Killed_by_Death]

I also think you're better off buying a portable PA that runs on batteries. Fender Passport, or something like that.
The truth is that when you put AC Voltage into a amplifier it converts it to DC for use internally.
So, if you're putting DC (battery) into an inverter, you're converting the Voltage twice.

 

[KohanMike]

I know my setup isn't anywhere near yours, but just for the sake of information for anyone interested; I have a Carvin MB15 200/250w combo amp with a 115MBE extension. I put together a 12v 25aH 300wH LiFePO4 lithium motorcycle battery with a 500w Pure Sine Wave inverter that lasts me a good 10 hours, and is very compact. I will also plug in a small 3 or 6 channel mixer. I keep the rig in an old lady shopping cart so I can move around and play from very easily.