Horrible voltage drop. What do i need to fix/upgrade?

[MrAcd]

So In my dodge ram have been worrying about my electrical lately. First I was looking at just upgrading to a AGM but I wanted to see if I even needed to, so I checked my voltage and rode around for a bit. the results..

HORRIBLE!

With the car at like 1800rpms cruising, I get dips down to 11v and for the longer bass notes it stays in the 12vish range. I would say around 80% of the tie driving the voltage was under 12.8v ..

At a read light, I had it full tilt for about 20 secs (didn't want to be annoying) and I hit 9v....that alone scared me, because I didn't want to lose my amp.

But I would say it was around 11v-13v through out the car ride. So my question is, why? This was measured at the amp I have a stock 136 amp alt that is the original as far as I know, and for my battery (don't laugh) a Wal-Mart Everstart Maxx 65S. I have the big three done and my amp is ran with 4 guage CCA wire. Grounded to the frame. I have a bass knob that tells me when im clipping, though my O scope should come in this week. But as far as I know my gains are set correctly, I used a True RMS DMM to set the gains. At idle with no music, I sit at about 13.9v-14v I think my voltage regulator is not allowing the standard 14.4v. I have this amp ran at 2 ohms so it isn't even that demanding for the electrical I have.

So is it my battery, alternator, or are there problems lying else where maybe like im soft clipping or there is a short or my ground isn't good? I tried to give all the info I can but if there anything else you need to know, ask. I don't want to fry my amp, im trying to get ever watt I can out of my amp.

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[TheFiverMan 10+ year member]

Check your grounds

 

[MrAcd]

Check your grounds

I just made it better not to long ago, I was attached to the seat belt bolt but then went ahead and drilled a hole through the chassis so I could ground directly to frame.

 

[OKAY]

I went through the same thing..had to turn the knob down soon as I came to a . Then i switched for a similar battery that was newer than mine. Days later, getting weaker. Im buying a agm today. I thought it wasnt my battery for the voltage drops..im big3 good connections..

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[MrAcd]

I went through the same thing..had to turn the knob down soon as I came to a . Then i switched for a similar battery that was newer than mine. Days later, getting weaker. Im buying a agm today. I thought it wasnt my battery for the voltage drops..im big3 good connections..
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Your think the agm will fix our issue? and how low where you dropping?

 

[OKAY]

Buy a new agm

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[dbjunior 10+ year member]

Check voltage at both locations if you read good under the hood and bad in back it's your wiring if both are low have you alt and battery tested at your local auto parts store you should be able to play that amp at .5ohm with a small second battery near amp.

 

[MrAcd]

Would you look at that, okay so under the hood I am getting 14v.. And when it's hitting 11v on the amp it's only hitting 13.9 at the battery. So the problem is within the wiring. Could it be my fuse?

 

[JoshC 10+ year member]

Would you look at that, okay so under the hood I am getting 14v.. And when it's hitting 11v on the amp it's only hitting 13.9 at the battery. So the problem is within the wiring. Could it be my fuse?

Somethings wrong, I ran my 1200.1 with a 90.4 on a big standard battery. Never below 13.1V at 1200wrms and I have a 3.7 ram

 

[los33]

Your think the agm will fix our issue? and how low where you dropping?

Would you look at that, okay so under the hood I am getting 14v.. And when it's hitting 11v on the amp it's only hitting 13.9 at the battery. So the problem is within the wiring. Could it be my fuse?

An agm will hold voltage longer at 12.5 then a normal lead acid battery, but the fact that you are reading 13.9 at the battery and 11v at the amp is caused by wire limitations.

How long is the 4 gauge?

At this point you can just upgrade to 0 gauge and use a 0 gauge to 4 gauge reducer. This will only maybe help you a bit at staying in the high 12's.

Adding a second battery closer to your amp will at that point keep you in the higher 13's.

Just remember tho the 4 gauge is reducing power due to heat, once you start upgrading as i stated above you will start to see more accurate voltage drop.

edit: also are you fused to your amps rating or for your wires rating?

 

[MrAcd]

An agm will hold voltage longer at 12.5 then a normal lead acid battery, but the fact that you are reading 13.9 at the battery and 11v at the amp is caused by wire limitations.How long is the 4 gauge?

At this point you can just upgrade to 0 gauge and use a 0 gauge to 4 gauge reducer. This will only maybe help you a bit at staying in the high 12's.

Adding a second battery closer to your amp will at that point keep you in the higher 13's.

Just remember tho the 4 gauge is reducing power due to heat, once you start upgrading as i stated above you will start to see more accurate voltage drop.

edit: also are you fused to your amps rating or for your wires rating?

My power wire is fairly short, around a 6ft piece iirc. The amp is only under the driver seat and the battery is against the firewall of the driver side. Im grounded to the frame. I have a 80 amp fuse on there. Even though it should be a 120 amp fuse. I have a 100 amp fuse i could try but i dont think that has anything to do with it since, the 80amp would pop over 80 not just restrict flow. I would assume 4 guage wire is fine for 800ish watts. What else can i check?

 

[Joseph7195 10+ year member]

Sup Bro! Thanks for the add!! But on to the important stuff. I had the exact same drop as you had. It's kind of a Dodge thang, but it's usually pretty easy to fix. The one thing Dodges are notorious for is the electrical. One of the reasons why, is the engine is not grounded to the frame properly. Behind your intake (The one with dodge on it)this thing here:



There is a crappy braided ground from a bolt on the back of the engine to the firewall. And that's it. Dodge didn't even take the time to remove the paint from the firewall before they attached it. So what that means is you have to find a point on the frame you can attach a ground to and connect it to the engine, this way you can make a full loop.

If you have already done this, yay!!! If not, i will be off work around 9 tonight and I will help you further Man!

 

[MrAcd]

Sup Bro! Thanks for the add!! But on to the important stuff. I had the exact same drop as you had. It's kind of a Dodge thang, but it's usually pretty easy to fix. The one thing Dodges are notorious for is the electrical. One of the reasons why, is the engine is not grounded to the frame properly. Behind your intake (The one with dodge on it)this thing here:

There is a crappy braided ground from a bolt on the back of the engine to the firewall. And that's it. Dodge didn't even take the time to remove the paint from the firewall before they attached it. So what that means is you have to find a point on the frame you can attach a ground to and connect it to the engine, this way you can make a full loop.

If you have already done this, yay!!! If not, i will be off work around 9 tonight and I will help you further Man!

Hey man, thanks for the input! but i have done the big three including a ground running from Alt case to the frame.

I had did a update in a post and found that under the hood, even with the hardest hitting songs my battery stays above 13.9 at idle. While i measured at the amp voltage i was getting 10-11v and on the same part on the same song while measuring at the battery, i was getting 13.9v-14.2v. So i dont think the probably is under the hood anymore. it has to be somewhere between the battery and the amp connection. Or the amp its self (gains or grounds) I have KNU 4 guage wire with a 80amp fuse on around a 6ft piece or wire, i dont think i should be getting that big of a drop, im only running the amp at 2 ohms....

On a side note though, i will definitely take a look at that and sand some paint off and bolt it to the frame, just for the sake of having a better ground

 

[wew lad 5,000+ posts]

how is your amp grounded? you can bump that fuse up to 100 or 120 amps, even 150, if the amp is already internally fused. 4 gauge ofc is good for up to 200 amps depending on length

 

[MrAcd]

how is your amp grounded? you can bump that fuse up to 100 or 120 amps, even 150, if the amp is already internally fused. 4 gauge ofc is good for up to 200 amps depending on length

I know i can bump it up, the 80amp fuse was just what i had laying around, do you think that can actually be limiting the current?

My ground is grounded directly to the frame off the truck. I drilled a hole through the floor and put a grommet on it and bolted it to the frame, sanded and all. I can get a picture if needed.