need battery help! Please

[Evan III]

I'm lost, and don't know anywhere else to ask. I know this isn't flasjlight related but I know some people here will have the anwser.

I have a self amplified 18 watt speaker that is designed to run off a 12 volt power supply in a vehicle. I want to run it on a portable sealed lead battery, but don't know how the amp hour and other ratings work. Here are some specs from the speaker.

supply voltage 10-16VDC
current draw @13.8 VDC
Standby 200MA, max
16 watt output 1.5 amps max
A note in the description says " A DC voltage source supplying 10 to 16 volts at 15 amperes is required to provide the proper power to this unit".

The battery I'm looking at is either
12 VDC 8 AH or
12 VDC 5 AH

Will these batteries work, will one work better then the other? Any idea how long either of these will last? Also Because it says 15 amperes does that mean 15 AH? If the two batts I listed won't be enough, anyone know what other light weight options are out there?

 

[SilverFox]

Hello Evan,

More Ah is always better.

You want to limit the discharge to less than 80% of the total capacity to get any kind of cycle life from your batteries. If we look at the 8 Ah battery, 80% would be 6.4 Ah. If your unit draws 1.5 amps, the battery will last for a little over 4 hours.

If you limit the discharge to 50% you will get more cycle life, but reduced run time. There is a bit of a balancing act that you need to do. Higher capacity batteries cost and weigh more, but deep cycling lower capacity batteries wears them out faster.

Tom

 

[mdocod]

Achieving sound pressure levels that most people consider adequate for normal listening often only takes between a fraction of a watt, and a couple watts to accomplish. Depending on the way that particular amplifier is designed, the 200mA power consumption may be all that is consumed during much of it's normal operation at reasonable listening levels, or it could be much higher depending on the efficiency of the design. Estimating runtime would be very difficult without actually testing the current flowing to the unit. Like Tom says, with the 1.5A draw taken into consideration (worst case scenario), the runtime would be about 4 hours, but I would venture to guess that it will likely run much longer, but am not going to slap any specific guess on it

Eric

 

[SilverFox]

Hello Eric,

I was going to be a little more generous with my run time estimate, but not knowing the variety of music being played, I decided to stick with a conservative estimate.

:devil: I am aware of some music styles that seem to incorporate very few pauses for reflection, and are usually played at levels higher than full volume...

Tom

 

[45/70]

:devil: I am aware of some music styles that seem to incorporate very few pauses for reflection, and are usually played at levels higher than full volume...

Is this kinda like when I'm playing Electric Blues on my computer, piping it through my double stack (16x9,15" and 18") bass amp rated @300 Watts RMS and the "limiter" LED is flashing, mostly staying on? :thinking:

A note in the description says " A DC voltage source supplying 10 to 16 volts at 15 amperes is required to provide the proper power to this unit".

I believe this reference to "15 Amperes" means that your power source needs to be able to supply 15 Amps "Peak", as info. I'm guessing that both the batteries you mention would work OK at this intermittent rate.

Dave

 

[Evan III]

Guys thanks alot for the info. I will not be using it to play music, it will be for a wireless hunting game caller that I'm making, so sounds will not be constant. Anyhow the info you guys have givin is exactlly what I needed. Thanks again!