Amp Hour ratings

[CJ18]

Can someone please explain IF or how the amp hour ratings of a battery effect a battery for the purpose of car audio.

[Dub7Banger]

I'm in for the answer too! But I was told like this. To determine how many batteries you need in a bank, you do

Amps from alternator(s) - (40 to 60, I go with 50. This is current that the car itself draws) - Amplifier draw (total amp fuses, i.e. 5x 30a fuses = 150 amp current draw). This should leave you with a negative number unless your cars electrical is awesome or you aren't trying to run a whole ish load of power. You need batteries with so many Ah to make up for this negative.

For example, my car has a stock 105 amp alt. So the math for hooking up my Memphis 16-st1500d to my car works like this.

105-50-150= -95

So I need a single battery, or a few batteries that total up to 95ah, but over hang is good!

I think this is right! At least it's how it was explained to me. Anyone else got better info chime in and tell me to stfu plz.

[AMI CUSTOMS]

From XS power

Could you explain “amp hours”?

People often wonder what the term “amp hours” means when referring to batteries. Many people assume that “AH” (amp hours abbreviated) is a standardized rating for a battery’s ability to discharge current; a true statement. The actual method for de terming the AH rating is more often times not fully understood by the automotive enthusiast.

AH capacity is measured in hours. AH is most commonly used to rate deep-cycle type batteries, or any type of battery used for relatively low discharge rates across an extended period of time. Most batteries, including XS Power batteries, are tested in a 20 hour cycle. AH tests can be performed for 10 hour cycles at a higher amp load, but results are not as useful for determining long term capacity.

An AH test can easily be conducted by the end user, which is why we at XS Power are so adamant about strict honesty regarding all of our battery ratings. To conduct your own AH test, simply calculate 5% of the AH capacity, and use that number as the amp load. Make sure the battery maintains the standardized 25°C temperature for the duration of the test. The idea is that the battery needs to maintain that load for 20 hours without falling below 10.5 volts. Please note that 16 Volt batteries would be tested to 14 Volts.

Here is an example for a 30 AH 12 Volt battery:

5% of 30 (amp hours) = 1.5 amps.

A 30 amp hour battery should be able to maintain a 1.5 amp draw for 20 hours at 25°C without falling below 10.5 volts.

When a manufacturer is initially determining AH, the calculation is done in reverse. The amp draw is multiplied by the test cycle length in hours as evidenced by the example below.

1.5 amps x 20 hours test = 30 AH

The AH rating is most useful for determining how well a deep cycle battery can maintain a relatively low amp load across an extended period of several hours, as the example above illustrates. This information is especially important to customers who plan to use XS Power batteries in Recreational Vehicles (RVs), boats, show vehicles, or any other application vehicle that will need to sustain a low draw for extended periods without being charged.

[CJ18]

How exactly would this translate into this situation.

XS Power D3400s how many based on the AH rating of 65 would it take to handle the Kicker Warhorse 10000.1

[AMI CUSTOMS]

How exactly would this translate into this situation.

XS Power D3400s how many based on the AH rating of 65 would it take to handle the Kicker Warhorse 10000.1

What is the demand of a warhorse and what voltage are you wanting to maintain? And are you trying to maintain 3 sec burp or streetbeat?

[CJ18]

What is the demand of a warhorse and what voltage are you wanting to maintain? And are you trying to maintain 3 sec burp or streetbeat?

I think the amp draw is between 400-600 amps not 100% sure. It is purely a street beater. I dont want my voltage to drop lower than 13.5. 14 would be ideal at full tilt.

Just so you know i am already putting 8 3400s being charged by 1 Mechman 270 w/adj voltage. I just want to know this for informational purposes when looking at building battery banks for other vehicles. I generally go by the total watts being put out by the system and double it when figuring a battery bank, but in my case I am tripling it with the 3400s being rated to handle 4000w each and 8 giving me 32000w of battery power.

[AMI CUSTOMS]

I think the amp draw is between 400-600 amps not 100% sure. It is purely a street beater. I dont want my voltage to drop lower than 13.5. 14 would be ideal at full tilt.

Just so you know i am already putting 8 3400s being charged by 1 Mechman 270 w/adj voltage. I just want to know this for informational purposes when looking at building battery banks for other vehicles. I generally go by the total watts being put out by the system and double it when figuring a battery bank, but in my case I am tripling it with the 3400s being rated to handle 4000w each and 8 giving me 32000w of battery power.

Well in your case, it is basically a function of time, batteries only do so much over time, if you are constantly pulling 500+ amps then you need alt to supply for music play. The bank will hold the voltage up for so long but once you pull the reserve off each battery the voltage will sag no matter if you had 10 or 100 batts, the voltage will drop, just take alot longer to happen the more batts you have. Add more alts, not batts.

My rule for doing a bank, if I am pulling over 10k watts, put as many batts in there as possible if I am only running one alt, and only play until the total voltage drops below 12.8 then recharge back up. For a few seconds even a minute dropping a battery below 12.5 is not that bad, just not for extended periods.

Edited October 18, 2010 by AMI CUSTOMS

[CJ18]

I have a dual alt setup. So far I have found that using just the dual alt to charge the back batteries holds my voltage better than it did when I had both alts charging all of my batteries. I have my stock location alt charging just my front battery which runs the truck and my 4 channel amps.

I will be adding a 3rd alternator the end of november also.

Edited October 18, 2010 by CJ18

[AMI CUSTOMS]

I have a dual alt setup. So far I have found that using just the dual alt to charge the back batteries holds my voltage better than it did when I had both alts charging all of my batteries. I have my stock location alt charging just my front battery which runs the truck and my 4 channel amps.

I will be adding a 3rd alternator the end of november also.

Yeah if you have multiple alts, then you only want the closest alt charging the underhood batt that runs the vehicle, and then all the other alts going to the bank and be sure to split up the load on the bank. You don't want to create a bottleneck!!!