How does AC DC work on the boat?

M

mrsrobinson

Well-Known Member
Mar 9, 2006
7,704
Virginia
Boat Info
2001 380DA
Engines
Caterpillar 3126
Like this:

I was tuning the new amp more when I noticed this, reminded me of the 1980s Hi Fi stereo components we had with needles.
 
Ericinmich said:
Wow, I've got a decent setup with a sub but never see those kind of swings. If that is real I can't believe your battery bank will last long!
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I only played it at the level for the length of that video, at the dock, on shore power, otherwise way too loud for me. I was testing 75%+ volume.

I thought it was an AC/DC music thing, so I tried a few more of their songs, and then others artists. Only this song produced spikes like that, interesting.
 
You should probably add some caps to the power input on the amp. Those voltage fluctuations would definitely causing distortion in the audio if they're making it to the amp.
 
What are caps, that's new to me.

Again this was at 75%+ volume, testing only, I'm not running the amp at these volumes. And at that volume there was no distortion, surprisingly, which as I understand it is the goal when setting your gaim to get it right.
 
My go-to amp adjustment songs are:

“Enigma” by Within The Ruins
”Hotel California” live 1994 acoustic by The Eagles

If you can hit those two right, it will play anything.

I second the suggestion for some capacitors
 
mrsrobinson said:
What are caps, that's new to me.

Again this was at 75%+ volume, testing only, I'm not running the amp at these volumes. And at that volume there was no distortion, surprisingly, which as I understand it is the goal when setting your gaim to get it right.
Click to expand...


A 1 Farad capacitor will smooth out and help stabilize the power feed. I have two of these for this purpose. The positive of the amp goes to the positive of the cap. The power feeding the amp also goes to the positive of the cap. Same for the negative.
 
the left gauge is the one you want smoothed out, even with a cap the right gauge will read the same since that's showing DC load.

I'd bet you find the voltage stays more stable with the engines running as your cat engines have pretty beefy alternators from the factory. In my car audio days one of the first things we'd do was swap to a high output alternator or our headlights would dim in sync with the bass. Cap will certainly smooth out the voltage drops though, which is what you want.

Another consideration, depending on how big of an amp(s) you have would be to run a bigger main power cable versus the factory 8 gauge, and that includes upgrading the ground.
 
Strecker25 said:
the left gauge is the one you want smoothed out, even with a cap the right gauge will read the same since that's showing DC load.

I'd bet you find the voltage stays more stable with the engines running as your cat engines have pretty beefy alternators from the factory. In my car audio days one of the first things we'd do was swap to a high output alternator or our headlights would dim in sync with the bass. Cap will certainly smooth out the voltage drops though, which is what you want.

Another consideration, depending on how big of an amp(s) you have would be to run a bigger main power cable versus the factory 8 gauge, and that includes upgrading the ground.
Click to expand...

Wouldn't the right (ampmeter) gauge flatten out as the short high surge draws are provided from the Cap? Sure, you want the left one not dipping down but the way to do that is not expect the batter to supply 50amps surges when the amp pulls it.
 
I used a test tone from Kicker, and my voltmeter to set the gain, seems to have worked well.

I listened to that same song in the car tonight. It's got a lot of bass hits compared to other songs on that album.

I posted this to be funny, but, great replies, looks like I got some work to do.
 
Ericinmich said:
Wouldn't the right (ampmeter) gauge flatten out as the short high surge draws are provided from the Cap? Sure, you want the left one not dipping down but the way to do that is not expect the batter to supply 50amps surges when the amp pulls it.
Click to expand...

Good point, depends where the cap is. If it’s close to the amp and past the meter then the gauge will smooth out as well.
 
Strecker25 said:
Good point, depends where the cap is. If it’s close to the amp and past the meter then the gauge will smooth out as well.
Click to expand...

The cap should be near the amp, usually mounted next to the amp. If it were before the gauge, it would be before the panel. So it needs to be after the breaker that is feeding the amp.
 
Before I go off and spend money on this capacitor, install it, etc.; do I really need this if I am not playing music at these volumes? This was only for a test. I don't play music that loud, the upgrades sound amazing "as is". It's stuff like this that kept me from moving forward with these upgrades, analysis paralysis, from all of you good folks telling me to buy this, add that, you must do this, :) don't install the amp without buying this, etc.

Is this a "Greg, if you plan to play music at those volumes then add this capacitor" ?

@Wylie_Tunes
 
mrsrobinson said:
Before I go off and spend money on this capacitor, install it, etc.; do I really need this if I am not playing music at these volumes? This was only for a test. I don't play music that loud, the upgrades sound amazing "as is". It's stuff like this that kept me from moving forward with these upgrades, analysis paralysis, from all of you good folks telling me to buy this, add that, you must do this, :) don't install the amp without buying this, etc.

Is this a "Greg, if you plan to play music at those volumes then add this capacitor" ?

@Wylie_Tunes
Click to expand...

IMO the answer is maybe. If the current meter is not bouncing up when you are using the sound system then now, not an issue. If you see it bouncing say from 5-20 amps, then I would say yes, as it a bit like quickly cranking an engine. Batteries don't like current excursions, thus the reason the voltage dips as it can't move enough electrons across the plates to keep up...
 
Ericinmich said:
IMO the answer is maybe. If the current meter is not bouncing up when you are using the sound system then now, not an issue. If you see it bouncing say from 5-20 amps, then I would say yes, as it a bit like quickly cranking an engine. Batteries don't like current excursions, thus the reason the voltage dips as it can't move enough electrons across the plates to keep up...
Click to expand...


So for $40 why wouldn't you just do it? ...
 
The same reason $40 x 10, 11, 12, etc. the last time the list started getting bigger and bigger with the things everyone said I must do before installing a new amp. That list and those comments paralyzed me, as witnessed by all of my posts then. My Amazon cart at one point was over $300 in parts, tools, gadgets and gidgets folks said I must install/upgrade before I installed my new amp.

And, if it ain't broke (for me) now, why fix it? I am extremely happy with the sound quality at the levels I like to play music at.
 
mrsrobinson said:
The same reason $40 x 10, 11, 12, etc. the last time the list started getting bigger and bigger with the things everyone said I must do before installing a new amp. That list and those comments paralyzed me, as witnessed by all of my posts then. My Amazon cart at one point was over $300 in parts, tools, gadgets and gidgets folks said I must install/upgrade before I installed my new amp.

And, if it ain't broke (for me) now, why fix it? I am extremely happy with the sound quality at the levels I like to play music at.
Click to expand...

If the way you play the music it's a steady draw than skip it (IMO). If you see the voltage dropping that means it is taking "effort" to supply the current, then a cap would help your batteries. That said, you likely dropped a couple boat units on a system that will wake the dead... why not have it reay to do that when you are out on the water and nobody within a mile or two!
 
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