How batts help?

[AXEHAMMER 16]

I put my mechman 240a alt on and have a group 65 diehard platinum under hood and small stinger in back. when playing full tilt on heavy bass im seeing low 12s. If i add another big plat in the back will this keep my voltage in the 13s or will it still drop to 12s as that's what the batteries rest at? this may be stupid question but none the less i am curious.

[jonbearsmt 919]

are you idled up or is that at idle?

 

 what amp and what ohm load.

 

 and have you check all your grounding points to insure they are good. allso have you grounded the alternator

[AXEHAMMER 16]

are you idled up or is that at idle?

 

 what amp and what ohm load.

 

 and have you check all your grounding points to insure they are good. allso have you grounded the alternator

That is while driving so idled up I would say.

Two Fosgate T1500bdcp ran at 2 ohm each and a Fosgate P800x4 on highs

Yes my grounds are good and alternator is grounded.

[ricksi30 923]

A battery would help.

[shizzzon 461]

u should put the stinger up front and the 65 in the back and see if that helps.

[AXEHAMMER 16]

I guess i should have said i am definatly adding another platinum to rear I just wondered if voltage would stay in 13s theoretically

[AXEHAMMER 16]

Or will it always dip to low 12s without a 300+ amp alternator?

[cloud77 28]

Wire matters too.  By a small stinger, you mean which?  IMO keep the die hard up front and get a big Xs Power in the back =]

[AXEHAMMER 16]

Its a 35a battery. pretty small. spv35 maybe?

[DanP 19]

Not trying to thread jack but How do you ground an alternator?

[cloud77 28]

Not trying to thread jack but How do you ground an alternator?

Yeah get out of here!  (I'm just mad because I don't know the answer)

[Julian 641]

Keep the diehards they are excellent batteries. pick up a G31 diehard AGM and that should be more than sufficient. 

[handman84 60]

Most alternators ground through the case so just run a cable from the mounting bolt to the frame. 

[AXEHAMMER 16]

The way i done mine was ground alt to battery which is grounded to frame

[pmureika 31]

A bigger battery will just give you more reserve power. The voltage will still drop to the high 12 volt range because your alternator & wiring can't keep up. Where are you measuring the voltage?

Edited May 22, 2013 by pmureika

[AXEHAMMER 16]

Thanks pm, that's what I was looking for. The volt meter is hooked up to the rear battery that both amps are connected to. I have almost literally zero voltage drop from front to back so I know that's good.

[pmureika 31]

How many runs of 0 gauge do you have to your amps?

[AXEHAMMER 16]

Just one run front to back. Never dreamed I would need more with no voltage drop...

[pmureika 31]

At 12.8 volts and if your amps are  drawing 3800 watts your at 297 amps going thru that zero gauge. If the voltage drops down lower than that the amp draw goes up. I think one run of zero gauge

Is past its max so I think there is voltage drop.

[kirill007 52]

There must be something wrong if you don't stay in the 13's with that alternator and those amps.

Can you measure the voltage at the alternator?

Then measure the voltage at the battery and see how much of a difference there is.

It's also pretty weird that there is no voltage difference at all from the front to the back.(did you measure with the system on?)

[AXEHAMMER 16]

it stays in 13s MOST of the time but not always as I would like.

yes, voltage at alt is 14.0 voltage at front battery 14.0 voltage at back battery 13.9

I have not measured them at full tilt but I will today.

Thanks everyone, especially pm, for explaining im maxing my one run out, makes perfect sense.

 

Edit-some songs DO take it down below 12v....

Edited May 22, 2013 by AXEHAMMER

[AXEHAMMER 16]

There must be something wrong if you don't stay in the 13's with that alternator and those amps.

Can you measure the voltage at the alternator?

Then measure the voltage at the battery and see how much of a difference there is.

It's also pretty weird that there is no voltage difference at all from the front to the back.(did you measure with the system on?)

I was thinking this too. Are there any specific things I could check?

[1two3 16]

u got a build log?

 

id love to see it