What is an acceptable voltage drop?

[serjr711. 10+ year member]

I idle in the morn @14.8v. Truck gets hot idle is @14.2-14.4v. When the bass hits at idle the voltage drops to 13.4v, 13.8v when driving. I thought I should stay at or above 14v with my electrical setup.

Big 3 done 0 gauge.

Dual alts 250amp 110@idle and 200amp 100amp@idle

2 runs of 0 gauge to rear

yellow top under hood, 4 c&d 78ah batts in rear, grounds are solid.

My sub amp is a Bxi 2610d running @ .7 ohm. My concern is whats gonna happen when I ad another Bxi 2610d.

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[Bettr n' Revrse 5,000+ posts]

**** with a couple 200 amps I bet youll be fine... maybe add another batt

 

[Buck 5,000+ posts]

You have a good electrical, but I don't think it should drop that low.

 

[serjr711. 10+ year member]

You have a good electrical, but I don't think it should drop that low.

I ran my amp @ 2 ohms and never dropped below 14.2v.

 

[Dirtrider4eva 10+ year member]

with such a low impedence, it is fair to assume your reaching 60% efficient, so lets your pulling about 2800 watts from the amp. at a rough equation (70 amps to 1000 watts) you want to push 2800 watts, well if it was possible ( which it isnt) at 100% efficiency your amperage would be just shy of 200 amps. nothing major correct? however since your efficiency is low. your amp is pulling roughly 360 amps due to the low efficiency rating and all. IF i am correct.

If i am not, i apologize.

 

[basscort2009 5,000+ posts]

yea i would bet its your batteries. they need to be trained for couple weeks aka like a 10 amp charge overnight everynight for like 2 weeks. should bring the resting voltage up and keep them higher during bassing.

this is my setup with minimal drop

stock alt

big 3 in 1/0

1 run of 1/0 to back.

sprinter 370 up front and 3 sprinter 370s in the rear

crossfire 1700 at .7 (pulls about 250 amps full tilt)

drop from 14.2 to 13.9 at most

 

[Ninesvnsicks 10+ year member]

With my stock alt I'm only getting about 13.7 volts which bums me out I might get a ho alt at some point if i can find a nice one for a decent price.

 

[LosIsATool 5,000+ posts]

Your VCM tells the alternator when to push current. I have beefy electrical and I still drop to the 12s on some tracks, cause my VCM *****. I will drop low then bounce right back up to 13.4. My batts keep me from going lower then 12.6. Just cause you add a HO does not mean it will hold high voltage better or charge any higher then it does now, it just wont drop as far and stay low long. They make aftermarket programable VCMs but not for all cars

 

[basshead442]

Hmm I have the same amp with a stock 90 amp alt and a Big 134 Ah C&D in the back and while driving I sit at 14.3 and drop to 13.1.

 

[serjr711. 10+ year member]

Went and reground the metal where my ground was and also added another 0 gauge ground, played the same song (soul survivor) and voltage dropped to 13.8v @ idle and 14.1v @ 1200 rpm:veryhapp:

 

[basshead442]

That sounds more like it man!

 

[ultimate157 5,000+ posts]

Those voltages are perfectly fine, but given your dual alt setup and such a "little" amp, I'd say its dropping too low for the setup.

Your power wires to the rear, you said dual runs of 1/0? Is that 2 (+) runs and grounding to the car, or one + and one -?

 

[Moble Enclosurs 10+ year member]

Technically, anything greater than a 0.05 Ohms, and between 0.03-0.05 is the optimum max for efficiency, obviously the best is none at all, But anything below 0.3 is good enough.

So, 14.2 down to 13.9 is ok.

 

[Joseph7195 10+ year member]

I am running the same amp with 2 batts (a xstatic 2000 and duralast 1000 amp) with stock alternator 136 amp. I have all 0 gauge and I am running at 1 0hm. I get a very very minor voltage drop at highway speeds (1500 RPM and i can't tell by gauge, only with a multimeter) and it's only noticeable when I am idling (700 RPM). It would be really cool to see some setup pics Bro!

 

[serjr711. 10+ year member]

Those voltages are perfectly fine, but given your dual alt setup and such a "little" amp, I'd say its dropping too low for the setup.
Your power wires to the rear, you said dual runs of 1/0? Is that 2 (+) runs and grounding to the car, or one + and one -?

2 runs of 0 gauge from front to rear battery bank. Then 2 0 gauge grounds from bank to chassis(rear seat mounting studs).