Help a newb with amp hitting low voltage cutoff

[Jcsaudio]

Maybe I don’t understand so please explain it to me how the voltage going into the fuse is 12.4-12.5. The voltage coming out of the fuse is 12.4-12.5 and that’s a 100% drop???? I hope where you can see how that would be confusing for someone to understand, because that looks like 0 drop in my math classes. In my work, for something to drop it has to go in one number and come out a lesser number. It’s good to see a forum where people are asking for help, and the ones that apparently know are “out” because one doesn’t understand. Obviously, if I had the answers, I wouldn’t be asking the question.

Try this test at all connections.

 

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Try this test at all connections.

Ahhh gotcha. No power on the system, correct? Just check it across the connection?

 

[THATpurpleKUSH 5,000+ posts]

Ahhhh yes. Definitely seeing a drop at the amp. The alternator is a 70 amp. I’m familiar with ohms law, and understand that won’t support the ~1600 watt demand, and I have a guy that can get mine to 180 amps, but it’ll technically lose its coast guard certification. But what in my mind, and I can fully accept that I could be wrong about this, if the battery itself (or the charging system) won’t meet the demand of the system, wouldn’t I see the drop at the battery?
I’m not meaning to be Hard headed but all the questions were answered in my first post. Battery voltage at every point of the wiring AND...... lthe battery type. Again They are XS XP3000 group 31 AGM batteries. XS claims they can run a 3000 watt system as a stand alone.....battery power only. They should handle my 1600 just fine.

That is your problem! That's what I've been saying all along.

Think about it- If your alternator was 100% efficient (which is pretty much impossible) it can only make 1008w at 14.4v. Your aftermarket amps combined with the existing electrical systems for the boat are taxing the fuck out of that dinky little alternator and it just can't keep up. Get a bigger alternator, at the minimum at least double the size of what you currently have.

 

[Rotate]

That is your problem! That's what I've been saying all along.
Think about it- If your alternator was 100% efficient (which is pretty much impossible) it can only make 1008w at 14.4v. Your aftermarket amps combined with the existing electrical systems for the boat are taxing the fuck out of that dinky little alternator and it just can't keep up. Get a bigger alternator, at the minimum at least double the size of what you currently have.

We don’t listen to it turned up moving across the water. That’s just irritating. We listen to it turned up at the beach, with no engine running. XS, and Kicker claim the batteries are more than capable powering the system on their own. I use the XS charger for their AGM batteries and put a full charge on them before every trip. The voltage at the battery doesn’t drop, so so why does it drop so much at the amp?

 

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Try this test at all connections.

I’m showing 0. Did it at the perko and fuse.

 

[THATpurpleKUSH 5,000+ posts]

We don’t listen to it turned up moving across the water. That’s just irritating. We listen to it turned up at the beach, with no engine running. XS, and Kicker claim the batteries are more than capable powering the system on their own. I use the XS charger for their AGM batteries and put a full charge on them before every trip. The voltage at the battery doesn’t drop, so so why does it drop so much at the amp?

Because the amp is pulling a lot of current from the battery and the battery doesn't have the capacity to feed the current draw. You probably get about 5-10mins of playtime at moderate volume before the amps shut down from the voltage drop because the batteries have drained.

 

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Because the amp is pulling a lot of current from the battery and the battery doesn't have the capacity to feed the current draw. You probably get about 5-10mins of playtime at moderate volume before the amps shut down from the voltage drop because the batteries have drained.

So in that scenario the volts would stay at 12.4? They wouldn’t drop? Because again, in my mind, to hit the voltage cutoff of 10.8V, the power supply (is....the battery) would have to drop to somewhere near there. I guess I truly don’t understand how the amp is hitting voltage cutoff, it the battery volts are staying so high. That makes no sense to me.

I’m curious if you’re familiar these batteries? On Sunday, I beached my boat at around 11:00am, turned the radio to 80% volume, and stayed there until about 4:30pm, never turned it down, and when I started the boat, the starter didn’t even drag. It started like it was a fresh battery, and that was just using one battery selected, and not both. The XP3000 is designed to run a 3000 watt system at 100% for something like 4-5 hours. This is what they’re designed to do.

 

[Jcsaudio]

Ahhh gotcha. No power on the system, correct? Just check it across the connection?

yes but while there is current flowing through the wire and connection, do this test.
Edit: PurpleKush guy is right.

 

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yes but while there is current flowing through the wire and connection, do this test.
Edit: PurpleKush guy is right.

About what? Are you talking about the alternator? Or why the battery doesn’t drop? He’s not right about the battery. Everything else, i surly don’t know but the batteries will without a doubt run both amps at high power for extended periods of time without dropping off. We are going to the lake tomorrow and I’ll take my multimeter and check it after hours of play time.

 

[garychoffmann 10+ year member]

Are your amps grounded to the battery?

 

[Jcsaudio]

About what? He’s not right about the battery. Everything else, i surly don’t know but the batteries will without a doubt run both amps at high power for extended periods of time without dropping off. We are going to the lake tomorrow and I’ll take my multimeter and check it after hours of play time.

He is right about the amperage of the alternator in/out of the battery, but that doesn’t matter. You should try that voltage drop test on all your suspect connections like the fuse block. Battery connections, and ground connections (at battery). Through the process of elimination, you can narrow it down to the cause, assuming you have a bad one somewhere near that amplifier. That 1 volt difference you stated at the amplifier doesn’t just disappear on its way to the amplifier unless there is enough resistance to make that happen. If there is a bad connection somewhere, then the voltage will drop at that point when high current flows through it. For example a voltage drop test across a 300 amp starter circuit on each side of the positive cable should be less than .5 volts.

 

[Rotate]

Are your amps grounded to the battery?

Let me start with my apologies, because I know these threads are fairly common, but here’s another. I recently had some upgrades installed in my boat.
Kicker KXMA 800.8 running 6 Wetsound 6.5s and a JL IB10”

Kicker KXMA 1200.1 running 2 12W6v3s @ 1 ohm

Battery is a XS XP3000

Each amplifier has its own dedicated Stinger 4 gauge for power and ground. From the battery to the amp it goes battery-perko switch-Stinger 150A fuse-amp

When I just start getting the volume right to where it’s almost max, the 1200.1 is hitting voltage cutoff, so I took some measurements.

Battery at rest is showing 12.9V

With the key off (ie.... no power to amp) voltage at the amplifier is 12.9V

With everything on and the volume high enough to cut the amp off.....

Battery - 12.4-12.5V

Out of the Perko 12.4-12.5V

Out of the 150A fuse 12.4-12.5V

Into the amplifier 11.2-11.4V

I’d estimate between the fuse and the amplifier is 12’-14’ of 4 gauge and no splices. The installer claims the KXMA1200.1 just isn’t enough for the 12W6s, and Kicker tech support says it’s a wiring install issue. Both the installer and Kicker agree that the 1200.1 having a dedicate 4 gauge with the length of the run, is sufficient. There’s never an issue at lower volumes, or if I turn the gain down on the amp a few clicks, so it’s strictly predicated on the draw of the sub amp. So what’s happening between the fuse and amp, that I’m getting over a 1 volt drop? The installer and the manufacturer will just continue to blame each other, so I’d like a 3rd party opinion so maybe I can actually fix it. Thanks in advance.

Well I was checking voltage on the actual wire after the fuse holder, just to rule that out and was getting 12.4-12.5V at high volume. As far as the ground, it’s grounded directly to the battery, because it’s in a boat, so there’s no paint. Thanks for the suggestions.

Yes

 

[Rotate]

He is right about the amperage of the alternator in/out of the battery, but that doesn’t matter. You should try that voltage drop test on all your suspect connections like the fuse block. Battery connections, and ground connections (at battery). Through the process of elimination, you can narrow it down to the cause, assuming you have a bad one somewhere near that amplifier. That 1 volt difference you stated at the amplifier doesn’t just disappear on its way to the amplifier unless there is enough resistance to make that happen. If there is a bad connection somewhere, then the voltage will drop at that point when high current flows through it. For example a voltage drop test across a 300 amp starter circuit on each side of the positive cable should be less than .5 volts.

Yessir. What weird is I’m getting good voltage out of the fuse and there is nothing between the fuse and the amp, except wire. No splices, or anything. That’s exactly what I can’t figure out.

 

[bigblank69 10+ year member]

Not to throw a monkey wrench in the discussion.... And not to doubt Kicker's crack tech support.... But are you sure the amp is shitting off due to low voltage.. I have a KXM1200.1 and those amps were only rated to go down 2 ohms... The KXMA series I know says it can do 1 ohms... but it might not be 1 ohm stable at 12V cranked up... Also how was the gain set on the amp?

 

[bigblank69 10+ year member]

That is your problem! That's what I've been saying all along.
Think about it- If your alternator was 100% efficient (which is pretty much impossible) it can only make 1008w at 14.4v. Your aftermarket amps combined with the existing electrical systems for the boat are taxing the fuck out of that dinky little alternator and it just can't keep up. Get a bigger alternator, at the minimum at least double the size of what you currently have.

Not that easy on a boat my friend, a lot of boats don't even have a Alternator, mine has a generator. Many marine amps are meant to be ran on battery power only....