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How Do More 12v Batteries Help a 14.4v System? - Noob Question


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Posted

Hello!

So, I know this may sound like a stupid question, but I am having a hard time wrapping my mind around this fully. Why do people insist on just adding another 12v battery when you could replace the alternator and get more amperage at 14.4v instead? And how do more 12v batteries help you maintain 14.4v while your system is bumping? I guess I just don't understand how more 12v supply would help reduce, say, dimming and voltage drop, since you actually want to stay at 14.4v. Wouldn't they really only give you more amperage once your alternator cannot keep up anymore, or when your car is off? I probably am thinking about this all wrong and would really like for someone to help explain it to me! When you add another battery, is it constantly helping you keep at 14.4v? Do people just add more batteries because its cheaper than an alternator? Or be cause they have already upgraded the alternator?

Again, sorry for the stupid question. Thanks!

Posted

Yup, batteries help solidify things at their resting voltage and prevent further voltage drop.

When demand goes beyond supply from the alternator, then voltage drops and if you don't have an appropriate reserve capacity (battery bank) then if you are really drawing beyond your alternators capabilities you drop sometimes into single digit voltage which is bad for everything.

There are 14v and 16v batteries, but those need to charge at approx. 16v or 18v and is a whole different ball game.

Posted

Ok! Sounds like we are on the same page! I always thought about it in this way! :) Its just, I've read things that make it seem like your battery/s somehow are constantly contributing, and somehow supply amperage at 14v or 13.5v or somewhere above their resting voltage (I assume around 12.6v-12.8v fully charged), and I never understood that. Are the batteries constantly contributing in some way? KyLar, maybe this has to do with the buffer you were talking about, feel free to elaborate!

Thanks for all the replys though! This is quite an interesting subject to me! :)

Posted

If you take a DMM and check the voltage of your batteries after your car has been running and been shut off you will see they carry a float charge somewhere 13ish and that will slowly drop down to resting voltage while the car is off.

That float voltage is the threshold where the battery starts to contribute, but that also becomes an additional load on your alternator because the battery wants more attention from the alternator when voltage drops below that, giving your alternator additional work. This is where having a good reserve kicks in, being able to hold that float/resting voltage longer under load.

Posted

A good electrical doesn't include just capacity/storage. Every setup is different but in some case simply adding a agm batt will be helpful. In other cases you will need more supply in order to be able to store what your alt is putting out.

personal goal of mine is to stay above 13v on music. I'll have roughly 200-250 amperage draw from the stereo on music. Electrical will consist of 250amp singer alt, biggest agm I can fit under the hood, plus whatever I can fit in back which won't be much. Will also have 2 runs 0gauge and solid frame grounds big 3 done with 0gauge all ofc wiring.

now if I only had say 50-80 amperage draw and the stick 105amp alt I would feel safe with a nice agm under the hood and 4guage with big 3 in 0 gauge. If it wasn't keeping above 13v then I would either up to a 150-200amp alt or second battery pending cheaper route.

t1500bdcp

2 t2d4 15"

1 t600.4

1 t400.2

1 set p1 tweets

singer alt, tons of wiring, smd vm-1, 80prs, back seat delete, still in the works, aiming for a 145-147 with the ability to play 25hz up to 50hz.

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