HO alternator vs Battery upgrade?

[wang in a stang]

I'm sure this question has been around alot but weirdly enough i feel like i have never gotten a super clear answer.

Firstly, what powers my amps when the car is running and if it's the alternator then is it really ONLY the alt that runs the power?

Second, i have been hearing a few times that the battery doesn't have anything to do with power when the engine is running, is this true? If so then why even bother with upgrading the battery?

I'm confused, sorry.

Anyway, My car is a 2004 stang. I am upgrading for a Skar ZVX-18 that is sitting three feet away from me, brand new. My amp will most likely be in the 1400-1800 RMS range and it'll be cheap chinese stuff cause i like the aestetics on a few of them.

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[wang in a stang]

Bumpin

 

[wew lad 5,000+ posts]

start here: Charging System Basics you can skim through the alternator internals

then read this: Upgrading Your Charging System

why are you bumping a one minute old thread

 

[wang in a stang]

On the usual forums i go to you must bump immediately or the thread will dissapear.

This place is different, i guess.

 

[Massive spl]

Alt power over batts. Anything above your batts resting voltage is all alternator power but batts do help.. If u can fit bigger/more alts I'd do that every time over buying battery's

 

[adulbrich 5,000+ posts]

Your alternator is supplying most of the power while the vehicle is running. If your amps pull more power than the alternator can supply, your batteries supply the necessary current.

A local friend and I have observed something with our setups. When you add a lot of batteries, your overall charging voltage is slightly lower even when nothing is drawing from the electrical system. For example, I went from one group 31 to five group 49's. With the single battery, I charged between 15.0v and 15.2v. With the battery bank, I charged between 14.8v and 15.0v. That's with the same alternator and nothing else changed. It may not seem like a big difference, but that's enough to get me into the safe zone for my current amp. 15.0v is fine, but it protects at 15.2v.

Also, I got less voltage drop with more batteries running the same power. We speculate that the batteries do hold a bit of voltage above their resting voltage. When you turn your vehicle off, if you have a voltage meter, you'll notice that the voltage doesn't immediately drop down to what they normally rest at. It sort of gradually lessens after the initial shut-off. To say that a battery only helps at "battery voltage" I think is untrue. Adding a battery can help voltage remain more constant.

However, I am a strong opponent of just adding batteries. If you don't have a HO alternator and your voltage is in the 12's, adding batteries is not a good idea. You'll constantly be draining them, and your alternator won't be able to maintain them. Eventually, your alternator will fail and you'll have to replace it anyways.

 

[wew lad 5,000+ posts]

the reason why you see current coming from batteries above 13v is capacitance, and thats one of the main reasons why im such a big advocate of using high quality batteries and multiple of them. Even when I drop to 13.5v or so I can still clamp current draw out of my batteries. the extra capacitance is very important imho but like adulbrich said, without an alternator that can keep up charging your batteries properly you're just going to reduce their lifespan and have to buy a new battery which over time would end up costing more than a HO alternator

 

[adulbrich 5,000+ posts]

Thanks, capacitance was the word I was looking for