Adding amplifier to stereo, Battery options?

K

kidafa

Petty Officer 2nd Class
Joined
Oct 31, 2010
Messages
105
Hi All,

Im currently researching and about to purchase the bits and pieces required to put an amplifier into my recently acquired 2006 Bayliner 175. For reference its got a 3.0L TKS Mercruiser with alpha one stern drive...

I don't see the music ever being on for more than 30 minutes without the engine running.


This is what the stereo consist of;


This is the amp i'm going to add: http://www.jlaudio.com/xd400-4-car-audio-xd-amplifiers-98261

I've chosen this amp because its a D class and It will easily run my stereo and It can capably run a small sub of it down the track if I would like.

Other accessories on-board include a small Garmin fish finder and then just your general nav lights ect....

What is my best method to power it all? I currently have a single battery. Would a large deep cycle battery be ok? When boat is not in use it is plugged in to a charger.
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Adding amplifier to stereo, Battery options?

The input power specs call for 4 gauge wire and a 50 amp fuse so this thing at its max level will draw some serious power. That said, even if you run the system for only 1/2 hour at a fairly high power level, you will need to run the engine for a fairly long time to replenish the power consumed. Just to give you a number to play with -- if the engine has a 60 amp alternator and you ran the system at or near its maximum power for 1/2 hour you would pull 25 amps from the battery. That 60 amp alternator would need to run at near full capacity for a minimum of 1/2 hour to top off the battery. That means a 10 minute run back to the dock is not going to make up the consumed power. Repeat the process three or four times and you will likely have a dead battery. Anytime one adds a high power device to a boat it is suggested that you add a second deep cycle battery to handle that load. You only need the stereo system on that battery. But in reality, if you operate the system as you say you will, and plug in the charger every time you hit the dock, the system will work fine with a single large deep cycle battery.
 
K

kidafa

Petty Officer 2nd Class
Joined
Oct 31, 2010
Messages
105
Re: Adding amplifier to stereo, Battery options?

I dont every see it being on for longer than half an hour if at all when the engine is off...

What would you define as a "large deep cycle battery" give me some specs ect ;-)
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Adding amplifier to stereo, Battery options?

Group size 27 minimum. Group size specifies the physical dimensions of the battery. Batteries in that group size generally have a spec such as RESERVE CAPACITY or RESERVE MINUTES: xxx @ 23 (or sometimes 25) amps. The XXX is the number of minutes the battery is capable of delivering 23 (or 25) amps before it can no longer do so. A typical number of reserve minutes for that size battery is 170 - 175. A group size 24 is smaller than a group size 27. Group sizes 29 and 31 are bigger than a 27.
 
K

kidafa

Petty Officer 2nd Class
Joined
Oct 31, 2010
Messages
105
Re: Adding amplifier to stereo, Battery options?

Anybody......?
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Adding amplifier to stereo, Battery options?

That is a "dual purpose" marine battery meaning it can be used for starting and deep cycle purposes. While that may seem like a good idea, dual purpose anything usually means there is a compromise and consequently the product does not do either function as well as a a product designed for a "specific" purpose. Starting batteries are designed for short term very high current draw as required to crank an engine. They are not designed to be deeply discharged on a regular basis. True deep cycle batteries are designed to deliver a relative low current over very long periods of time without damage and withstand repeated cycling. Any deep cycle can be used to start an engine and they often are used for that purpose. However, this particular battery does not seem to have what I would consider to be sufficient capacity but then we have no idea what your current drain requirements are. A 20 AHr battery can deliver 20 amps for 1 hour or 1 amp for 20 hours. 10 amps for 2 hours. The reserve capacity (reserve miinutes) are indicated as 160 (about 2.5 hours). So this is likely equivalent to a smaller group size 24 battery. While this may serve your purpose for 1/2 hour operation of the stereo, batteries must not be discharged more than 50% so based on the limited information you've provided, this is an absolute minimum capacity. I would also prefer a true "deep cycle" not a dual purpose battery.
 
S

Slide

Petty Officer 1st Class
Joined
Aug 2, 2010
Messages
269
Re: Adding amplifier to stereo, Battery options?

FYI, Silvertip's analysis is a little incorrect, as it is based on the 50A fuse. That system will not pull anywhere close to 50A, ever. The purpose of the 50A fuse is to prevent damage to your amp in case of some sort of surge. Watts = Volts * Amps; you have an amp that will supply 75w continuos x 4 channels = 300W. 300W / 14.6V (average battery voltage) = 20A draw. And that is if you are maxed out. Your battery will be right as rain.
 
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