Question running 2 batteries

[robbierob02]

I just joined here as I been getting all my car audio help here for a while and cannot seem to find an answer to my question.

I'm about to be adding a second battery to my truck due to a huge voltage drop in my electrical. My starter battery is providing enough juice to keep my truck going but when I kick in my stereo then my voltage drops. I got the battery checked at autozone and said it needs replacing but since it has enough life to power everything but my stereo i would like to keep it running until taxes to replace that one too. I want to add this second battery for my system and for my air compressors as my truck is bagged. Will wiring them in parallel kill my 2nd battery since the starter battery is on its way out?

Starter battery is yellow top optima and I will be runnin the same battery for my system too

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[bubbagumper6 5,000+ posts]

I just joined here as I been getting all my car audio help here for a while and cannot seem to find an answer to my question.
I'm about to be adding a second battery to my truck due to a huge voltage drop in my electrical. My starter battery is providing enough juice to keep my truck going but when I kick in my stereo then my voltage drops. I got the battery checked at autozone and said it needs replacing but since it has enough life to power everything but my stereo i would like to keep it running until taxes to replace that one too. I want to add this second battery for my system and for my air compressors as my truck is bagged. Will wiring them in parallel kill my 2nd battery since the starter battery is on its way out?

Starter battery is yellow top optima and I will be runnin the same battery for my system too

There will be people on both sides of this fence but the truth is you should NOT connect a new battery directly to an old battery even if they are the same brand. A battery isolator is cheap insurance for maximizing the life of both of them.

 

[orphe 10+ year member]

There will be people on both sides of this fence but the truth is you should NOT connect a new battery directly to an old battery even if they are the same brand. A battery isolator is cheap insurance for maximizing the life of both of them.

Totally agree to a point.

I would not even put the new battery in at all.

 

[mylows10 5,000+ posts]

The old battery will pull down the new batteries power to match which will lessen the life of the new battery

 

[bubbagumper6 5,000+ posts]

Totally agree to a point.I would not even put the new battery in at all.

I wasn't suggesting or agreeing that he should add the new battery, just telling him it's not a good idea to connect them together if he does go that route.

 

[robbierob02]

So would putting the isolator in between be the safe route? I just didn't want to run an isolator cause I've been reading there is a voltage loss to the second battery so it would charge slower, is that right?

 

[jrdnhsnbrg 10+ year member]

So would putting the isolator in between be the safe route? I just didn't want to run an isolator cause I've been reading there is a voltage loss to the second battery so it would charge slower, is that right?

Isolators are not the ideal fix here, it's like putting duct tape over a pothole. If you use enough of it, it might hold for a little while, but in the end you're probably going to do more harm than good. If I were you I'd disconnect your amp(s) until you can afford a new battery, running on low voltage will hurt your alternator and equipment.

 

[bubbagumper6 5,000+ posts]

So would putting the isolator in between be the safe route? I just didn't want to run an isolator cause I've been reading there is a voltage loss to the second battery so it would charge slower, is that right?

There may be some voltage drop across the isolator but I wouldn't think it would be significant enough to hurt anything. It's essentially a giant relay contactor, when the low current circuit is energized it connects two big pieces of metal to make the connection. The only voltage drop would be the resistance through that metal to metal connection which, like I said, shouldn't be significant.

 

[bubbagumper6 5,000+ posts]

Replace the front battery and go easy on the volume knob until you can afford to add another or upgrade your alternator.

What kind of power are you running? What amplifiers specifically?

 

[robbierob02]

I'm running two Rockford p300-1's, 2 10" p2's to each and an alpine four channel for my mids and highs.

 

[robbierob02]

My voltage only occurs with my volume over 32 so I got in the habit of keeping it low to prevent the voltage drop. Should the amps still be disconnected?

 

[bubbagumper6 5,000+ posts]

Those amps are only 300w each so even with your 4 channel you can't be running much more than 800w total. If you replace your front battery with a new yellowtop you should be fine (assuming your alternator is in good working condition).

No you don't need to disconnect your amplifiers, just keep the volume low until you can get your electrical problems fixed.

 

[robbierob02]

Okay cause eventually I was going to do a blowthrough with two DB drive K9's so when that project comes around I should definitely get a second battery right? That will be adding 2000w to my system. And I already have upgraded from the stock 105a alt to a 145a

 

[bubbagumper6 5,000+ posts]

Okay cause eventually I was going to do a blowthrough with two DB drive K9's so when that project comes around I should definitely get a second battery right? That will be adding 2000w to my system. And I already have upgraded from the stock 105a alt to a 145a

Eh, I wouldn't run that kind of power on anything smaller than a 200A alt....batteries will help but your alternator's life will be shortened

 

[robbierob02]

So should a 270a alt be plenty of power? Plus a second batt..