2 Battery Setup, Do Amplifiers Pull Off Both When On?

Hi Team - If this question is already posted please point me to the forum/link where I can find an answer. I added a 2nd battery in the trunk of my Jetta, run in parallel, the 1/0 POS+ for the second coming off of the + terminal on the primary under the hood, 1/0 + from alternator to primary battery, only. I have a 250A battery isolator that is connected to a relay so it closes when ignition is on/opens when off.

Question is this: When the car is on, stereo on, everything is powered up and running and the isolator is in the Closed position acting normal, will my amplifiers pull off of both batteries? Or just the 2nd AUX battery?

I'm curious because my 2nd battery is junk and I'm waiting for a new one I ordered at Sonic, and when I turn it up with bass gain high, the bass amp (Taramps HD 3000.1 running single 12" Audiopipe XPsomething 2500W(?) 4ohm DVC wired at 2ohms) I turn it up and the sub amp goes into protect. I'm not surprised because the 2nd battery is cracked and leaking (I stuck bubble gum on it while I'm waiting for the new one) Wouldn't the amplifiers draw off the primary under the hood if the secondary does not have the power needed?
No capacitors, the batteries are ~6' apart, Big Three done, replaced sub amp RCA interconnects, re-grounded. This is the second new amplifier I've had do the same thing (before it was a SKAR RP 2000.1 that did it first, I unloaded that amp after the mfr "did a full diagnostic scan on it", twice, and it persisted.

Any help and insight is greatly-appreciated, Thank you in advance. Work in process, please excuse the mess.



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2006 Volkswagen Jetta TDI, manual
"Mechanical don't care"

wow that's really over kill for that amp that's in there. Second battery is mainly for extended key off time (according to mecp basic book). Your suppose to use the same battery for front and rear as well, better hope the one in the trunk doesn't vent into the car and the what looks like corrosion on the ground terminal scares me. At least they used a battery idolater. Unless you are pushing extremely high wattage your better off just doing the big 3 (replace alternator, wiring from battery to alternator and battery). personally id take it (2nd battery and isolator) out and run the amp to the front battery

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33 years as a installer now just a retired old guy. Favorite thing to install/topic are remote starts/car alarms. Stop using test lights!!!

Thank you for that, I'm building a solid foundation to continue future builds. Any ideas on my question?

wow im sorry some how I blew rate past all the question you posted (look a squirrel moment) and went on to the pictures. Does the amp go into protect mode with no speakers/rca hooked to it? What kinda of voltage reading are you getting with the ddm at the power and ground

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33 years as a installer now just a retired old guy. Favorite thing to install/topic are remote starts/car alarms. Stop using test lights!!!

No worries! Totally get it. That high quality piece of Walmart Special interior amplifier, Dual, does not go into Protect, as near as I can figure it's does not have such high technology. I have yet to put DMM on it as I'm working and on call but I will have an answer by tomorrow. Another thought that struck me is this: Obviously that's a yard sale enclosure that the bargain sub is in, I have it wired: amp to terminal with 12-, and the DVC wired down to 2ohm with 12-: Is it likely that the 12- wire is choking the signal at high volume and kicking the amp into Protect? Just a thought.

I appreciate your insight.

BINGO. My coworker is an electrician I just used his DMM, it's voltage drop. It already started low at 9.5v, I played a track by Nas at low bass gain and medium volume and it dropped to 9.1 when the amp went into protect.

I'm grateful for your assistance pointing me in the right direction. Good thing I have a monster replacement battery on my front porch!

Still curious though: When the car is on, do the amplifiers only draw a load on the closer battery?

Thank you.

They'd draw from all current sources collectively - think of it like 2 pools connected by a hose. If you suck from one it'll pull water from the other to level itself with 2nd pool. They end with same water levels, always, just the concept of 'potential difference' basically. Hope that helps.