2nd battery...

[Ali1 10+ year member]

Not to hijack this thread, but since we're on this topic. so if i had a stock alt with a redtop under the hood. if i add 2-3 yellowtop in the trunk, it should help significantly, or is just a waste of money?

The reason i say this is because i called maxxsonics about an amp (colossus II). He said a bigger alternator is not necessary, if you have 2-3 batteries in the trunk, it would help signicifcantly.

my stock alt is 105amps.

 

[knukonceptz 10+ year member]

You are a perfect example - the amp is rated to draw 300A (got that from ebay so it might be wrong - Hifonics does not mention in the manual)

You will easily exceed the stock alt and pretty much any HO ALT out there with one amp. Regardless of what is happening in the 12.9-14V range (which I have tried to point out - there is a discharge) adding the batteries will strengthen the "support" in the 12V (and subsequently in the 13-14V range ) by the added reserve. If you have say one battery rated at 1000A vs 3 or 4 batteries of the same capacity, which do you think will hold a load longer?

 

[Ali1 10+ year member]

the 3 or 4.....

let's say i play music like the song "static addict" with the constant bass. Won't that eventually drain my batteries? How long does it take for the alternator to charge a battery back to 14v after playing music like that? Does it take hours or just a quick minute?

 

[knukonceptz 10+ year member]

If you start will charged batteries and you let the car idle while listening to any song it would take a very very long time for you to kill your battery reserve doing this non-stop. The actual time would be based on ampere hour of each battery and the draw coming from the amp.

See Post #37 (last paragraph) on recharging. The regulator will output what needs to be "refilled" Again this all depends how depelted the batteries are

 

[Thnking 10+ year member]

Yes, they do operate at VA, and the number of amps draw is relative to the voltage - thus why capacitors are in the amp to smooth out voltage for the power supply.You clearly have never seen an amp go bad, because obviously something is exceeding the manufactured "design". Low voltage will keep an amp from turning on initially. Once that sucker is on and working hard, the protect circuit will not always save you especially when driving an amp at a low impedance.

I just explained to you how under voltage damages an amplifier, I’ve built SS amplifiers before.

Go pick up a book on amplifier construction if you need more information.

As I stated above, amperage is coming from out of the battery in the 13-14V range - there is no other explanation for it, otherwise everytime a load exceeded the ALT we'd all drop instantly to 12.8V and that is not what happens.

You obviously didn’t read what I stated very well.

Let me repeat it AGAIN

“I’m sure that what would happen in a situation where the alt was underrated for the load, is that the duty cycle of the music was high enough to take an average reading of 13V, while the actual voltage was dipping well below that number (or at least low enough to allow the batteries to discharge enough). 2.1V is a large dip for a daily driver, I know I wouldn’t tolerate that.”

But just for the sake of arguement - even if it isnt - the second battery in the rear WOULD strengthen the charging system by adding reserve and maintain a 12V load longer then a single battery and lower voltage loss from resistance in the cabling. 12V is what the power supply will and can work on. My whole point is that not everyone can get a HO Alt for there car - either they do not fit or the customer can not afford it. Adding one would be great if you can, a second battery however is atleast 1/2 the price and will certainly provide a benefit to anyone chossing that option.

I agree that an extra battery will help maintain voltage around or under 12V, but that’s still a noticeable voltage drop.

If someone doesn’t care than go with an extra battery, but with HO alternators running around 225$ - around 200amps, an extra battery with wiring could even be more $ depending on the battery.

 

[drperry]

Adding a second battery, will increase the maximum current draw of the systems (with the alternator off)

Lets say you have a battery that can discharge at 150 amps constantly, if you put another identical battery, wired in paralell, you can discharge at 300 amps constantly, also, your reserve power is doubled.

Basic electrical theory: batteries in series adds voltage together (something you do NOT want in your car //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif ) batteries in paralell adds the capacity of the batteries together.

It's also better to have multiple battery systems, to have the SAME battery model for each battery instance.

Exceeding the alternator output, will cause the lights to dim, due to the voltage drop, multiple batteries will help with this, but not entirely eliminate it, more batteries, will mean higher current capacity, wich equals more stable voltage (most unloaded batteries are about ~13V)