low voltage on brand new batt? need some help

[Deeper_shades 10+ year member]

I was running a shuriken bt100 under my hood, and it would get up to 14.4v when the car is idling, I decided to add a second batt, I bought a new kinetic 1800 for my trunk and I tested it while running, and it wont stay past 12.11v???? this was with no music, and only my 4 channel amp hooked up. when I start my car it jumps up to 13.5v and than right back down to 12.11v //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

ive done the big three, grounded right off to my frame in the rear, and i have a mechman 150a h/o alt, and 1/0 gauge cable all around.

what could the problem be?

Click to read more...

 

[Deeper_shades 10+ year member]

wtf? could the batt be a dud?

 

[DarkScorpion 10+ year member]

What does the battery rest at by itself? As in, not hooked up to the other battery.

 

[audiolife 5,000+ posts]

Should charge it up with an agm charger (should be sitting between 12.8 to 13.1 v when it is fully charged) and then check your grounds and fuses. Always before you install a battery charge it or at least see if it is resting at at least 12.5 volts prior to installation. If it was resting higher than 12.11 prior to use I would look at the fuses. grounds and overall installation. The dealer or person you bought it from could have had it sitting awhile without upkeep.

 

[DarkScorpion 10+ year member]

The dealer or person you bought it from could have had it sitting awhile without upkeep.

That's what I was thinking. The battery itself could be shot...

 

[audiolife 5,000+ posts]

Doubtful though if the battery is resting at 12v + kept at room temps it more than likely needs a charge. I just recovered a few year kinetik hc2400 that was sitting outside for 9+ months resting at under 5 volts, looks pretty spiffy sunfaded and all LOL

 

[Deeper_shades 10+ year member]

turns out it was a bad fuse.......//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

fixed the problem, back up to 14.4v

thanks for your suggestions