Acceptable voltage drop

[Water Bear]

With the electrical in my Tahoe, it drops about 0.2 volts during peak bass (just a hair below clipping). At cruising RPM w/ no audio, voltage is around 14.4 on both batteries. I'm thinking the electrical can take more. What's a safe limit? How much drop is acceptable before we burn out the alt or have problems?

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[metalheadjoe 10+ year member]

What's your goal? I suspect you already to know the answer to your question.

 

[Water Bear]

What's your goal? I suspect you already to know the answer to your question.

Goal is to add another 2k watts (which the subs can take) but only if it's not going to require further electrical upgrades.

 

[audiobaun 5,000+ posts]

Goal is to add another 2k watts (which the subs can take) but only if it's not going to require further electrical upgrades.

What is your electrical supply wiring consist of? Big3 done?Do you only have the two batteries that are in your sig or anothyer under the hood and what is it?? What amp are you looking to place in for 2k more rms on tap/Total RMS Sub amp and Mids and Highs amp?? What are your spec read outs for amperage/testing output at what RPM for the alternator installed?

 

[metalheadjoe 10+ year member]

I bet if you replaced your XS batteries with 40ah of LiFePO4, you would be good to go.

To your original question: any quality product won't fail because it is tasked with its intended purpose. It bothers me that mechman has such a short warranty, but I believe if something fails it should be upgraded. Don't let the possibility of failure limit your enjoyment! Break, upgrade, repeat.

 

[Water Bear]

All I really want to know is acceptable voltage drop, or a rough range. Given any well upgraded electrical, I'm guessing that 0.2 V is acceptable. What do you guys think is safe for a well designed, functioning system? If you sit in a demo car and the voltage drops to X, what does X have to be for you to look at the owner like "bro you're about to roast this thing"?

 

[HardofWhoring]

Well, you won't burn out your alt, and you won't damage your equipment, you will just get less power.
If anything, I would THINK that with a serious voltage drop the biggest concern is going to be problems to the vehicle itself. I know dropping to 13v won't do much, but you may see your lights dim. You start dropping below that/12v, I could only guess you might cause a sensor fault from lack of voltage, might cause problems to your ignition including a misfire from coils not sending a full spark. You drop it low enough you could kill the battery if you pull too much voltage and are still trying to keep the stereo up. Amps have a working voltage, so if you drop below that, I would only guess it would go into protect.

I'm surprised nobody has a better answer though.

 

[TheBigPilferer]

.2v is completely normal. What will happen when you exceed your alternators capacity is your voltage will then drop to 12.6-12.8 immediately bc your battery is the next source of power and that is the voltage it rests at.

Without knowing your alternator amperage, I can't really say at what point this will happen with any certainty, but it's safe to assume that adding 2000 additional watts will definitely be well past this point.

The only solution is a high output alternator or a lithium bank.

 

[winkychevelle 10+ year member]

Personally I don't want to see anything less than 13v with AGM and nothing less than 14.6v with my current lto.

You are usually safe down to 12.6v but below that current starts to rise rapidly

 

[HardofWhoring]

.2v is completely normal.

What will happen when you exceed your alternators capacity is your voltage will then drop to 12.6-12.8 immediately bc your battery is the next source of power and that is the voltage it rests at.

No. Absolutely not. That is 100% out of your ass.

Without knowing your alternator amperage, I can't really say at what point this will happen with any certainty, but it's safe to assume that adding 2000 additional watts will definitely be well past this point.

The only solution is a high output alternator or a lithium bank.

 

[Water Bear]

.2v is completely normal. What will happen when you exceed your alternators capacity is your voltage will then drop to 12.6-12.8 immediately bc your battery is the next source of power and that is the voltage it rests at.

Without knowing your alternator amperage, I can't really say at what point this will happen with any certainty, but it's safe to assume that adding 2000 additional watts will definitely be well past this point.

The only solution is a high output alternator or a lithium bank.

I've got a Mechman 370 elite and 2x XS D3400's (AGMs). All well and good but I'm looking at full bridge amps which draw plenty of current. I think what I'll do is look for amp dynos to see what kind of current draw happens at 5k for amps like I'm considering. I don't really want my alt to be putting out max amps for any length of time though because that seems like it would burn it up.

It sounds like "over 14 preferable or high 13's" is safe.

 

[TheBigPilferer]

I've got a Mechman 370 elite and 2x XS D3400's (AGMs). All well and good but I'm looking at full bridge amps which draw plenty of current. I think what I'll do is look for amp dynos to see what kind of current draw happens at 5k for amps like I'm considering. I don't really want my alt to be putting out max amps for any length of time though because that seems like it would burn it up.

It sounds like "over 14 preferable or high 13's" is safe.

That certainly is useful information, and it never hurts to always plan your system around the maximum draw, just to play it safe. With that said, unless you're competing in SPL or playing full tilt sine waves you will generally only draw about half of the maximum draw on most normal music. Exception to this would be if you're playing re-bassed/decaf music where the bass lines are basically 0 db sine waves.

I was a bit concerned about my factory electrical being up to par on my 98 QX4 (100 amp alternator with 2 year old standard lead acid battery) with 1400 total RMS in amp power, and I've had zero problems. The lowest I drop is 14.17 from 14.37, and that's with the AC on full blast, bright headlights, etc.

I'm glad I have an SUV. Cabin gain is highly in my favor, and my system is as loud as some other systems (in trunk builds) with 3x the power. Not that I really care about Spl numbers or anything personally, but I originally intended upon upgrading little by little and I've found that to be (fortunately) unnecessary. Now I'm just focused upon improving sound quality.

I actually had a Sundown SIA-1750 I was going to install that I'd picked up off marketplace in good condition, but I ended up using it for another project and selling it. It never fails to amaze me how much people are willing to pay for the Sundown name.

 

[TheBigPilferer]

Btw, I didn't answer whether or not you'll be able to support 5k bc I can't answer the question with 100% certainty.

I can say that yes, 14s is preferable and high 13s is perfectly safe.

Full bridge amps do have a reputation of being less tolerant to low voltages than half bridge designs, as well as less tolerant to wiring lower than their recommended impedance. Taramps (unsure if newer ones are better) also don't like high input RCA voltage - they're rated to accept 4v in but lots of folks have had best luck feeding them 3-3.2v. Not sure which amp you're looking at purchasing, but it's something to keep in mind.

 

[johhny]

I'm lost on same issue

 

[Water Bear]

Btw, I didn't answer whether or not you'll be able to support 5k bc I can't answer the question with 100% certainty.

I can say that yes, 14s is preferable and high 13s is perfectly safe.

Full bridge amps do have a reputation of being less tolerant to low voltages than half bridge designs, as well as less tolerant to wiring lower than their recommended impedance. Taramps (unsure if newer ones are better) also don't like high input RCA voltage - they're rated to accept 4v in but lots of folks have had best luck feeding them 3-3.2v. Not sure which amp you're looking at purchasing, but it's something to keep in mind.

That's kind of why I asked the question the way I did. I don't expect anyone to know if a specific electrical set up will work for a specific amp unless they happen to have done it themselves, which is probably rare. It's better to know a voltage target and then upgrade to hit that. I have a Tahoe so it's easy to go buy alternator brackets and stuff like that if I really need 'em.

Thanks for your answer by the way, very useful info. My system is getting loud, but it's honestly not as loud as I expected. Two NSv4's on 3k in a Gately box. (Got a decent price on the NSv4's off eBay. Otherwise wouldn't have gone with that). Part of the issue here is that I need hella sound deadener. The poor Tahoe is gonna rattle apart at max output, and all that rattling is energy lost to noise that could be making volume. So I gotta learn how to do that job properly.

For what it's worth, I'm looking at an SFB 8k but there's other options out there which I might try just for fun. And I do listen to decaf mixes sometimes.