ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1]   Go Down

Author Topic: Purchasing a Battery and Power Inverter to Run My PA  (Read 1939 times)

Louis Miller

  • Newbie
  • *
  • Offline Offline
  • Posts: 4
Purchasing a Battery and Power Inverter to Run My PA
« on: July 16, 2018, 11:29:42 am »

Hello Forum!

I've not posted before but am in need of some guidance and hoping I might find it here . . .

I am preparing to purchase a deep-cycle battery, along with a pure-sine power inverter, to run a pair of Yamaha MSR100 speakers during outdoor performances. I've done a good deal of research but I'm concerned that I may not full understand the power consumption of the speakers.  Both are 100w speakers, and the specs say that they each have a power consumotion of 70w.  At a total of 140 watts, I caculated that the speakers consume ~ 12 amps, and that a 50 amp-hour battery could therefore power these speaks for ~ 4 hours (without factoring in % efficiency of the power inverter).

Is 70w correct, or is it only the "idle" power consumotion?  Do they draw more than 140 watts when in use? I'll need to know this in order to purchase the right battery and the right power inverter.  Thanks so much if any one you can offer some input!

-Lou
Logged

Frank DeWitt

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1010
    • LBP DI Box
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #1 on: July 16, 2018, 03:37:10 pm »

I suspect that you will find that the speakers draw 70watts at full power (At there max volume) and considerably less at idle.  You can confirm this by purchasing a device called Kill-a-watt (about $25)  Do give some thought to how you are going to ground the AC power.
Logged
Not to Code

Art Welter

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1763
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #2 on: July 16, 2018, 05:26:37 pm »

Hello Forum!

I've not posted before but am in need of some guidance and hoping I might find it here . . .

I am preparing to purchase a deep-cycle battery, along with a pure-sine power inverter, to run a pair of Yamaha MSR100 speakers during outdoor performances.  At a total of 140 watts, I caculated that the speakers consume ~ 12 amps, and that a 50 amp-hour battery could therefore power these speaks for ~ 4 hours (without factoring in % efficiency of the power inverter).

Is 70w correct, or is it only the "idle" power consumotion?  Do they draw more than 140 watts when in use?
Lou,

The speakers each have a 100 watt amp, at best they are about 90% efficient, so peak power will be over 200 watts for the pair. Average power, "full tilt boogie" will not exceed 70 watts per unit, but likely would be less than 30 watts per unit with typical music run to clipping.

"Pure sine wave" inverters are nice for audio, but many inexpensive stepped square wave inverters are plenty clean enough for any decent audio products.

There are two important factors in your purchase of the battery, number one is the cycle life of lead -acid batteries will be severely reduced if depleted past 50%, about 12.06V when rested.
The other important factor is Peukert's Law.
Peukertís law states that as the rate of discharge increases, the available capacity of that battery decreases.
SLA batteries amp hour rating is often given over a 20 hour period, if the amperage is discharged in a much shorter time, the battery voltage will drop rapidly, and the amp hour rate will be diminished.

LiFePO4 batteries have virtually no Peukert's effect, can be cycled to 80%, and can deliver as much as 10 times their rated amperage for short duration peaks. They are far lighter than lead-acid batteries. Although they are far more expensive initially, as they can deliver around 2000 cycles to 80-90%, they are actually more cost effective in the long run.

Protection-circuit-modules (PCM) that internally balance cells and provide protection from overcharge should be used with iFePO4 batteries, and are typically built in for "12volt" deep-cycle replacements.

Art
« Last Edit: July 16, 2018, 05:31:32 pm by Art Welter »
Logged

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6065
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #3 on: July 16, 2018, 06:55:07 pm »

Lou,

The speakers each have a 100 watt amp, at best they are about 90% efficient, so peak power will be over 200 watts for the pair. Average power, "full tilt boogie" will not exceed 70 watts per unit, but likely would be less than 30 watts per unit with typical music run to clipping.

"Pure sine wave" inverters are nice for audio, but many inexpensive stepped square wave inverters are plenty clean enough for any decent audio products.

There are two important factors in your purchase of the battery, number one is the cycle life of lead -acid batteries will be severely reduced if depleted past 50%, about 12.06V when rested.
The other important factor is Peukert's Law.
Peukertís law states that as the rate of discharge increases, the available capacity of that battery decreases.
SLA batteries amp hour rating is often given over a 20 hour period, if the amperage is discharged in a much shorter time, the battery voltage will drop rapidly, and the amp hour rate will be diminished.

LiFePO4 batteries have virtually no Peukert's effect, can be cycled to 80%, and can deliver as much as 10 times their rated amperage for short duration peaks. They are far lighter than lead-acid batteries. Although they are far more expensive initially, as they can deliver around 2000 cycles to 80-90%, they are actually more cost effective in the long run.

Protection-circuit-modules (PCM) that internally balance cells and provide protection from overcharge should be used with iFePO4 batteries, and are typically built in for "12volt" deep-cycle replacements.

Art

LiFeP04 batteries are awesome.  If you love a senior using a mobility device, upgrade them to these!  About $2500 for a 25ah deep cycle replacement. 
Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Mark Cadwallader

  • Hero Member
  • *****
  • Online Online
  • Posts: 1337
  • Helena, Montana USA
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #4 on: July 16, 2018, 07:07:35 pm »

LiFeP04 batteries are awesome.  If you love a senior using a mobility device, upgrade them to these!  About $2500 for a 25ah deep cycle replacement.

For less money (perhaps a lot less) the OP could buy a Honda inverter generator. Not knowing the circumstance of intended use, I don't know if that is a feasible option. If it might be feasible, the little inverter generators are very quiet, lightweight, and pretty darn fuel efficient. 
Logged
"Good tools are expensive, but cheap tools are damned expensive."

Lyle Williams

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1556
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #5 on: July 17, 2018, 04:44:10 pm »

An economical lead-acid and inverter will do fine.
Logged

Kevin Graf

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 331
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #6 on: July 18, 2018, 08:43:41 am »

Note that ordinary deep-cycle lead-acid batteries are not the same as automobile batteries.  They are designed to be repeatedly discharged.  Think golf-cart batteries.
Logged
Speedskater

Doug Johnson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 270
  • Rhoadesville, VA
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #7 on: July 18, 2018, 01:46:50 pm »

I would recommend sealed batteries of your application.  I would prefer to minimize the chance of a battery acid leak during transport or use.   I had a friend that drove an electric forklift for a living, just being in proximity to the batteries result in holes in his clothing.

For two 70 volt loads, for four hours of use, you  would need a battery bank with 45 amp hour rating at an 80% discharge rate and a low temperature battery capacity of 90%.  If you use a 24 volt supply (two 12 volt batteries in series and a 24 volt inverter) your battery bank rating drops to 24 amp hours total.  This accounts for a 10 watt power consumption by the inverter.  Remember to always allow for ventilation when recharging, especially with non-sealed batteries.
« Last Edit: July 18, 2018, 01:50:08 pm by Doug Johnson »
Logged

Jeff Bankston

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2394
Re: Purchasing a Battery and Power Inverter to Run My PA
« Reply #8 on: August 06, 2018, 02:42:10 pm »

Kill-a-watt
How do you Kill-a-watt ? Answer > drop voltage on it !
Logged

ProSoundWeb Community

Re: Purchasing a Battery and Power Inverter to Run My PA
¬ę Reply #8 on: August 06, 2018, 02:42:10 pm ¬Ľ


Pages: [1]   Go Up
 



Page created in 0.073 seconds with 23 queries.